Optical information recording medium

The present invention relates to an optical information recording medium for carrying out recording, reproduction and erasing with laser beams which comprises a support having carried thereon at least one methine dye which consists of an azulene nucleus, at least one of 10 carbon atoms of which is replaced by chalcogen atom(s) and/or nitrogen atom(s), and further whose 7-membered ring part is substituted with a methine bond having at the terminal an auxochrome which forms a conjugated resonance chromophore together with a 10 .pi. electron system of the nucleus. Optical information recording media of the invention have adequate recording characteristics having high C/N, and have high stabilities against long-term preservation or against long-time reading.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to optical information recording media each 
having a recording layer containing a novel dye. Particularly, the 
invention relates to optical information recording media wherein recording 
and reproduction are carried out using laser beams. 
2. Description of the Prior Art 
Heretofore, information recording media wherein recording and reproduction 
of information are each carried out by irradiating a rotating disc-shaped 
information recording medium with a laser beam have been known. As 
recording layers in these information media, those wherein metals having 
low melting points, or metals having low melting points and dielectric 
substances are used are proposed. However, these recording layers have 
disadvantages such as poor preservability, low resolution, low recording 
density and high manufacturing cost. Recently, it has been proposed and 
practised that dye films whose physical properties may be changed with 
light of relatively long wavelength are used in recording layers. However, 
dyes which have absorption bands in long wavelength generally have 
problems. For example, one problem is that they have only low stabilities 
against heat and light. Thus, it is currently the cases that recording 
layers having recording characteristics which are stable over a long 
period of time and satisfactory have not yet been developed. 
SUMMARY OF THE INVENTION 
Thus, the object of the present invention is to provide optical information 
recording media each having a dye recording layer which is capable of 
maintaining adequate recording characteristics over a long period of time 
and thus is excellent in stability. 
The object of the invention has been attained by an optical information 
recording medium which comprises a support having carried thereon methine 
dye(s) which each consist(s) of an azulene nucleus, at least one of 10 
carbon atoms of which, preferably at least one of carbon atoms at the 1- 
and 3-positions of which is replaced by chalcogen atom(s) (for example, 
oxygen atom(s), sulfur atom(s), selenium atom(s), tellurium atom(s) or the 
like) or nitrogen atom(s) (hereinafter referred to as a heteroazulene 
nuleus), and further whose 7-membered ring part is substituted with a 
methine bond having at the terminal an auxochrome which forms a conjugated 
resonance chromophore together with 10 .pi. electron system of the 
nucleus. 
DETAILED DESCRIPTION OF THE INVENTION 
Such a methine dye exhibits stability of a level higher than that expected 
based on the number of methine groups in the chromophore, and exhibits an 
absorption peak in a relatively long wavelength. These advantages are 
attributable to the existance of a heteroazulene nucleus in the dye. 
Methine dyes used in the present invention each consist of a heteroazulene 
nucleus which is substituted with a methine bond having an auxochrome at 
the terminal. The 10 .pi. electron system and auxochrome of the 
heteroazulene nucleus are bound together through carbon atoms lying 
between them. As is seen from the bond through carbon atoms between the 
heteroazulene nucleus and the auxochrome, the pattern of an alternative 
single bond and a double bond exists and each dye may be represented by 
two different formulae. These two formulae represent the limit of 
different resonance states, and in these two formulae positions of the 
single bond and the double bond binding carbon atoms are exchanged. That 
is, the heteroazulene nucleus and the auxochrome form a conjugated 
resonance chromophore through the bond. 
Generic characteristics of dyes used in the present invention may be 
understood by taking the synthesis of them into consideration. The 
heteroazulene nucleus used as a starting substance for synthesis of a dye 
of the present invention has a positive charge, which activates at least 
one of the nucleus carbon atoms of the heteroazulene nucleus or a methyl 
substituent thereof as a reactive site. This activated nucleus carbon atom 
of the heteroazulene nucleus can be regarded as a carbocation in one 
resonance form. When the instant carbon atom is methyl-substituted, a 
carbanion is formed by deprotonization of the methyl substituent in one 
resonance form. A methine bond is formed from a carbocation (positive) or 
carbanion (negative) site of the heteroazulene nucleus. 
Although there are many embodiments consistent with the above general 
explanation, the present invention will be explained by citing typical 
embodiments. 
In a methine dye containing a heteroazulene nucleus as used in the present 
invention, the preferred heteroazulene nucleus is an azulene nucleus, at 
least one of carbon atoms at the 1-and 3-positions of which is replaced by 
chalcogen atom(s) or nitrogen atom(s). Therefore, such a nucleus is 
explained below as a representative example. 
Dyes of the present invention may be represented as alternative resonance 
forms as shown in the following general formula (I): 
##STR1## 
wherein E represents an auxochrome; L represents a methine bond; V.sub.1, 
V.sub.2, V.sub.3, V.sub.4 and V.sub.5 each represent hydrogen atoms, 
halogen atoms, substituted or unsubstituted alkyl groups, acyl groups, 
acyloxy groups, substituted or unsubstituted alkoxycarbonyl groups, 
substituted or unsubstituted carbamoyl groups, substituted or 
unsubstituted sulfamoyl groups, carboxyl groups, cyano groups, hydroxyl 
groups, amino groups, acylamino groups, substituted or unsubstituted 
alkoxy groups, alkylthio groups, alkylsulfonyl groups, sulfonic acid 
groups, or aryl groups, or alternatively two of V.sub.1 to V.sub.5 linking 
to adjacent carbon atoms may combine to form a condensed ring. 
Y and Z each represent carbon atoms 
##STR2## 
wherein V has the same meaning with V.sub.1, V.sub.2, V.sub.3, V.sub.4 and 
V.sub.5), chalcogen atoms (for example, oxygen atoms, sulfur atoms, 
selenium atoms, tellurium atoms or the like) or nitrogen atoms 
##STR3## 
wherein R.sub.1 is in some occasion necessary for forming a nucleus and in 
the other occasion unnecessary, and when needed, represents a hydrogen 
atom, a substituted or unsubstituted alkyl group, a substituted or 
unsubstituted aryl group or a heterocyclic ring group), provided that Y 
and Z do not represent carbon atoms at the same time. Further, when Y and 
Z are represented by chalcogen atoms or nitrogen atoms, at least one of 
them is a nitrogen atom. Further, when one of Y and Z represents a 
chalcogen atom, and the other represents a carbon atom or a nitrogen atom, 
Z represents a chalcogen atom and Y represents a carbon atom or a nitrogen 
atom. 
M represents a counter ion for charge balance, m is the number of 0 or more 
necessary for balance of charge. 
Bonding position of a methine bond L was representatively expressed as the 
6-position in the formula (I), but may also be expressed as another 
position (4-, 5-, 7-or 8-position). However, preferred bonding positions 
of L are the 4-, 6- and 8-positions, particularly 4-and 6-positions. 
The auxochrome E is explained in more detail below. 
E may take an arbitrary general form found in methine dyes. Typically, the 
auxochrome is composed of nitrogen or chalcogen atoms, and resonates 
between a charged state and an uncharged state in the dye. E may take any 
form of auxochromes found, for example in cyanine, merocyanine, oxonol, 
pyrylium or thiapyrylium dyes. However, it is not necessary to restrict 
the auxochrome to such species. Though not so general, auxochromes 
composed of other atoms such as phosphorus or boron atoms may be 
mentioned. For example, 2-triphenylphosphoro-1,3-cyclopentadiene-5-yl may 
be mentioned. 
Preferred dyes among those represented by the general formula (I) are those 
represented by the following general formulae (II) to (IX). 
##STR4## 
wherein 
V.sub.1 to V.sub.5, Y, Z, M and m have the same meanings as those in the 
general formula (I); the position of the methine bond may be any of the 
4-, 5-, 6-, 7- and 8-positions, as is in the general formula (I); 
Q.sub.1 represents an atomic group necessary for forming a 5- or 6-membered 
nitrogen-containing ring; L.sub.1, L.sub.2, L.sub.3, L.sub.4 and L.sub.5 
each represent methine groups which may optionally be substituted; 
R.sub.2 represents a substituted or unsubstituted alkyl group; l represents 
an integer of 0 to 3; and n.sub.1 represents 0 or 1. 
##STR5## 
wherein 
V.sub.1 to V.sub.5, Y, Z, M and m have the same meanings as those in the 
general formula (I); the position of the methine bond may be any of the 
4-, 5-, 6-, 7- and 8-positions, as is in the general formula (I); 
Q.sub.2 represents an atomic group necessary for forming a 5- or 6-membered 
nitrogen-containing ring; L.sub.6, L.sub.7, L.sub.8, L.sub.9 and L.sub.10 
have the same meanings with L.sub.1, L.sub.2, L.sub.3, L.sub.4 and L.sub.5 
; 
R.sub.3 represents a substituted or unsubstituted alkyl group; 
l.sub.2 represents an integer of 0 to 3; and n.sub.2 represents 0 or 1. 
##STR6## 
wherein 
V.sub.1 to V.sub.5, Y, Z, M and m have the same meanings as those in the 
general formula (I); Y' and Z' have the same meanings as Y and Z, 
respectively; the position of the methine bond may be any of the 4-, 5-, 
6-, 7- and 8-positions; 
V.sub.1 ' to V.sub.5 ' have the same meanings as V.sub.1 to V.sub.5, 
respectively; L.sub.11, L.sub.12 and L.sub.13 have the same meanings as 
L.sub.1, L.sub.2, L.sub.3, L.sub.4 and L.sub.5 ; and l.sub.3 represents an 
integer of 0 to 3. 
##STR7## 
wherein 
V.sub.1 to V.sub.5, Y, Z, M and m have the same meanings as those in the 
general formula (I); the position of the methine bond may be any of the 
4-, 5-, 6-, 7- and 8-positions, as is in the general formula (I); 
D.sub.1 and D.sub.1 ' each represent atomic groups necessary for forming an 
acidic nucleus, and may be a cyclic or cyclic; 
L.sub.14, L.sub.15, L.sub.16 and L.sub.17 have the same meanings with 
L.sub.1, L.sub.2, L.sub.3, L.sub.4 and L.sub.5 ; l.sub.4 represents an 
integer of 0 to 3; and n.sub.3 represents 0 or 1. 
##STR8## 
wherein 
V.sub.1 to V.sub.5, Y, Z, M and m have the same meanings as those in the 
general formula (I); the position of the methine bond may be any of the 
4-, 5-, 6-, 7- and 8-positions, as is in the general formula (I); 
R.sub.4 and R.sub.5 represent substituents known in general tertiary 
amines, and R.sub.4 and R.sub.5 may combine to form a ring; 
L.sub.18 and L.sub.19 have the same meanings as L.sub.1, L.sub.2, L.sub.3, 
L.sub.4 and L.sub.5 ; and l represents an integer of 0 to 3. 
##STR9## 
wherein 
E and E' each is E.sub.1 or E.sub.2, provided that at least one of E and E' 
is E.sub.1 ; 
V.sub.1 to V.sub.5, Y, Z, M and m have the same meanings as those in the 
general formula (I); the position of the methine bond in E.sub.1 may be 
any of the 4-, 5-, 6-, 7-and 8-positions, as is in the general formula 
(I); 
W.sub.1 represents an atomic group necessary for forming a 5- or 6-membered 
heterocyclic ring; 
R.sub.6 represents a hydrogen atom, a substituted or unsubstituted alkyl 
group, a substituted or unsubstituted aryl group or a heterocyclic group; 
Q.sub.3 and R.sub.7 have the same meanings as Q.sub.1 and R.sub.2 in the 
general formula (II), respectively; 
L.sub.20, L.sub.21, L.sub.22, L.sub.23, L.sub.24, L.sub.25 and L.sub.26 
have the same meanings with L.sub.1, L.sub.2, L.sub.3, L.sub.4 and L.sub.5 
; 
l.sub.6 and l.sub.7 are integers of 0 to 3; and n.sub.4 is 0 or 1. 
##STR10## 
wherein 
V.sub.1 to V.sub.5, Y, Z, M and m have the same meanings as those in the 
general formula (I); the position of the methine bond may be any of the 
4-, 5-, 6-, 7- and 8-positions, as is in the general formula (I); 
W.sub.2 has the same meaning as W.sub.1 ; R.sub.8 has the same meaning as 
R.sub.6 ; 
D.sub.2 and D.sub.2 ' have the same meanings as D.sub.1 and D.sub.1 ' in 
the general formula (V), respectively; 
L.sub.27, L.sub.28, L.sub.29, L.sub.30, L.sub.31 and L.sub.32 have the same 
meanings as L.sub.1, L.sub.2, L.sub.3, L.sub.4 and L.sub.5 ; 
l.sub.8 and l.sub.9 are integers of 0 to 3; and n.sub.5 represents 0 or 1. 
##STR11## 
wherein 
V.sub.1 to V.sub.5, Y, Z, M and m have the same meanings as those in the 
general formula (I), the position of the methine bond may be any of the 
4-, 5-, 6- and 8-positions, as is in the general formula (I); 
L.sub.33 and L.sub.34 have the same meanings as L.sub.1, L.sub.2, L.sub.3, 
L.sub.4 and L.sub.5 ; 
Ar represents an aromatic group; and l.sub.10 represents an integer of 0 to 
3. 
The general formulae (I) to (IX) are described below in detail. 
Preferred examples of R.sub.1 include a hydrogen atom; an unsubstituted 
alkyl group having 18 or less carbon atoms (for example, a methyl, ethyl, 
propyl, butyl, pentyl, octyl, decyl, dodecyl or octadecyl group or the 
like); a substituted alkyl group {an alkyl group having 18 or less carbon 
atoms substituted with a carboxyl group, a sulfo group, a cyano group, 
halogen atom(s) (for example, fluorine, chlorine or bromine atoms or the 
like), a hydroxyl group, an alkoxycarbonyl group having 8 or less carbon 
atoms (for example, a methoxycarbonyl, ethoxycarbonyl, phenoxycarbonyl or 
benzyloxycarbonyl group or the like), an alkoxy group having 8 or less 
carbon atoms (for example, a methoxy, ethoxy, benzyloxy or phenethyloxy 
group or the like), a monocyclic aryloxy group having 10 or less carbon 
atoms (for example, a phenoxy or p-tolyloxy group or the like), an acyloxy 
group having 3 or less carbon atoms (for example, an acetyloxy or 
propionyloxy group or the like), an acyl group having 8 or less carbon 
atoms (for example, an acetyl, propionyl, benzoyl or mesyl group or the 
like), a substituted or unsubstituted carbamoyl group (for example, a 
carbamoyl, N,N-dimethylcarbamoyl, morpholinocarbonyl or piperidinocarbonyl 
group), a substituted or unsubstituted sulfamoyl group (for example, a 
sulfamoyl, N,N-dimethylsulfamoyl, morpholinosulfonyl or piperidinosulfonyl 
group), a substituted or unsubstituted aryl group having 10 or less carbon 
atoms (for example, a phenyl, 4-chlorophenyl, 4-methylphenyl or 
.alpha.-naphthyl group or the like), or the like}; an aryl group (for 
example, a phenyl or 2-naphthyl group or the like); a substituted aryl 
group (for example, a 4-carboxyphenyl, 4-sulfophenyl, 3-chlorophenyl or 
3-methylphenyl group or the like); and a heterocyclic group (for example, 
a 2-pyridyl or 2-thiazolyl group or the like). 
More preferably, R.sub.1 is an unsubstituted alkyl group (for example, a 
methyl or ethyl group or the like) or a sulfoalkyl group (for example, a 
2-sulfoethyl, 3-sulfopropyl or 4-sulfobutyl group or the like). Most 
preferably, R.sub.1 is a methyl group. 
A metal atom capable of forming a salt with R.sub.1 is preferably an alkali 
metal, and an organic compound capable of forming a salt with R.sub.1 is 
preferably a pyridine or an amine. 
V.sub.1, V.sub.2, V.sub.3, V.sub.4, V.sub.5, V.sub.1 ', V.sub.2 ', V.sub.3 
', V.sub.4 ' and V.sub.5 ' each are preferably hydrogen atoms, halogen 
atoms (for example, chlorine atoms, fluorine atoms, or bromine atoms), 
unsubstituted alkyl groups having 10 or less carbon atoms (for example, 
methyl or ethyl groups or the like), substituted alkyl groups having 18 or 
less carbon atoms (for example, benzyl, .alpha.-naphthylmethyl, 
2-phenylethyl or trifluoromethyl groups), acyl groups having 10 or less 
carbon atoms (for example, acetyl, benzoyl or mesyl groups or the like), 
acyloxy groups having 10 or less carbon atoms (for example, acetyloxy 
groups or the like), substituted or unsubstituted alkoxycarbonyl groups 
(for example, methoxycarbonyl, ethoxycarbonyl or benzyloxycarbonyl groups 
or the like), substituted or unsubstituted carbamoyl groups (for example, 
carbamoyl, N,N-dimethylcarbamoyl, morpholinocarbonyl or piperidinocarbonyl 
groups or the like), substituted or unsubstituted sulfamoyl groups (for 
example, sulfamoyl, N,N-dimethylsulfamoyl, morpholinosulfonyl or 
piperidinosulfonyl groups or the like), carboxyl groups, cyano groups, 
hydroxyl groups, amino groups, acylamino groups having 8 or less carbon 
atoms (for example, acetylamino groups), substituted or unsubstituted 
alkoxy groups having 10 or less carbon atoms (for example, methoxy, ethoxy 
or benzyloxy groups or the like), alkylthio groups (for example, ethyl 
groups or the like), alkylsulfonyl groups (for example, methylsulfonyl 
groups or the like), sulfonic acid groups, or aryl groups (for example, 
phenyl or tolyl groups). Two of V.sub.1 to V.sub.5 which link to adjacent 
carbon atoms may combine to form a benzene ring or a heterocyclic ring 
(for example, a pyrrole ring, a thiophene ring, a furan ring, a pyridine 
ring, an imidazole ring, a triazole ring, a thiazole ring or the like). 
Preferred V.sub.2, V.sub.3, V.sub.4, V.sub.5, V.sub.2 ', V.sub.3 ', V.sub.4 
' and V.sub.5 ' each are hydrogen atoms. Preferred V.sub.1 and V.sub.1 ' 
each are hydrogen atoms, chlorine atoms, alkoxy groups (for example, 
methoxy groups or the like), alkylthio groups (for example, methylthio 
groups or the like) or aryl groups (for example, phenyl groups or the 
like). 
When necessary for neutralizing the ion charge of the dye, Mm is contained 
in the formula for exhibiting the presence or the absence of cation(s) or 
anion(s). It depends on the auxochrome and the substituent whether a dye 
is a cation or an anion or whether the dye has ion charge. The counter ion 
may readily be exchanged after the preparation of the dye. Typical cations 
are an ammonium ion and alkali metal ions. The anion may specifically be 
an inorganic ion or an organic ion, and examples thereof include halide 
anions (for example, fluoride, chloride and iodide and the like), 
substituted arylsulfonate ions (for example, p-toluenesulfonate and 
p-chlorobenzenesulfonate ions and the like), aryldisulfonate ions (for 
example, 1,3-benzendisulfonate, 1,5-naphthalenedisulfonate and 
2,6-naphthalenedisulfonate ions and the like), alkylsulfate ions (for 
example, a methylsulfate ion and the like), a sulfate ion, a thiocyanate 
ion, a perchlorate ion, a tetrafluoroborate ion, a picrate ion, an acetate 
ion, a trifluoromethanesulfonate ion, and the like. An iodide ion is 
preferred. 
Examples of a nucleus formed containing Q.sub.1 or Q.sub.2 include a 
thiazole nucleus (for example, thiazole, 4-methylthiazole, 
4-phenylthiazole, 4,5-dimethylthiazole, 4,5-diphenylthiazole or the like), 
a benzothiazole nucleus (for example, benzothiazole, 
4-chlorobenzothiazole, 5-chlorobenzothiazole, 6-chlorobenzothiazole, 
5-nitrobenzothiazole, 4-methylbenzothiazole, 5-methylbenzothiazole, 
6-methylbenzothiazole, 5-bromobenzothiazole, 6-bromobenzothiazole, 
5-iodobenzothiazole, 5-phenylbenzothiazole, 5-methoxybenzothiazole, 
6-methoxybenzothiazole, 5-ethoxybenzothiazole, 
5-ethoxycarbonylbenzothiazole, 5-carboxybenzothiazole, 
5-phenethylbenzothiazole, 5-fluorobenzothiazole, 
5-chloro-6-methylbenzothiazole, 5,6-dimethylbenzothiazole, 
5,6-dimethoxybenzothiazole, 5-hydroxy-6-methylbenzothiazole, 
tetrahydrobenzothiazole, 4-phenylbenzothiazole or the like), a 
naphthothiazole nucleus (for example, naphtho(2,1-d)thiazole, 
naphtho(1,2-d)thiazole, naphtho(2,3-d)thiazole, 
5-methoxynaphtho(1,2-d)thiazole, 7-ethoxynaphtho(2,1-d)thiazole, 
8-methoxynaphtho(2,1-d)thiazole, 5-methoxynaphtho(2,3-d)thiazole or the 
like), a thiazoline nucleus (for example, thiazoline, 4-methylthiazoline, 
4-nitrothiazoline or the like), an oxazole nucleus {an oxazole nucleus 
(for example, oxazole, 4-methyloxazole, 4-nitrooxazole, 5-methyloxazole, 
4-phenyloxazole, 4,5-diphenyloxazole, 4-ethyloxazole or the like), a 
benzoxazole nucleus (for example, benzoxazole, 5-chlorobenzoxazole, 
5-methylbenzoxazole, 5-bromobenzoxazole, 5-fluorobenzoxazole, 
5-phenylbenzoxazole, 5-methoxybenzoxazole, 5-nitrobenzoxazole, 
5-trifluoromethylbenzoxazole, 5-hydroxybenzoxazole, 5-carboxybenzoxazole, 
6-methylbenzoxazole, 6-chlorobenzoxazole, 6-nitrobenzoxazole, 
6-methoxybenzoxazole, 6-hydroxybenzoxazole, 5,6-dimethylbenzoxazole, 
4,6-dimethylbenzoxazole, 5-ethoxybenzoxazole or the like), a naphthoxazole 
nucleus (for example, naphtho(2,1-d)oxazole, naphtho(1,2-d)oxazole, 
naphtho(2,3-d)oxazole, 5-nitronaphtho(2,1-d)oxazole or the like) or the 
like}, an oxazoline nucleus (for example, 4,4-dimethyloxazoline or the 
like), a selenazole nucleus {a selenazole nucleus (for example, 
4-methylselenazole, 4-nitroselenazole, 4-phenylselenazole or the like), a 
benzoselenazole nucleus (for example, benzoselenazole, 
5-chlorobenzoselenazole, 5-nitrobenzoselenazole, 5-methoxybenzoselenazole, 
5-hydroxybenzoselenazole, 6-nitrobenzoselenazole, 
5-chloro-6-nitrobenzoselenazole, 5,6-dimethylbenzoselenazole or the like), 
a naphthoselenazole nucleus (for example, naphtho(2,1-d)selenazole, 
naphtho(1,2-d)selenazole or the like) or the like}, a selenazoline nucleus 
(for example, selenazoline, 4-methylselenazoline or the like), a 
tellurazole nucleus {a tellurazole nucleus (for example, tellurazole, 
4-methyltellurazole, 4-phenyltellurazole or the like), a benzotellurazole 
nucleus (for example, benzotellurazole, 5-chlorobenzotellurazole, 
5-methylbenzotellurazole, 5,6-dimethylbenzotellurazole, 
6-methoxybenzotellurazole or the like), a naphthotellurazole nucleus (for 
example, naphtho(2,1-d)tellurazole, naphtho(1,2-d)tellurazole or the like) 
or the like}, a tellurazoline nucleus (for example, tellurazoline, 
4-methyltellurazoline or the like), a 3,3-dialkylindolenine nucleus (for 
example, 3,3-dimethylindolenine, 3,3-diethylindolenine, 
3,3-dimethyl-5-cyanoindolenine, 3,3-dimethyl-6-nitroindolenine, 
3,3-dimethyl-5-nitroindolenine, 3,3-dimethyl-5-methoxyindolenine, 
3,3,5-trimethylindolenine, 3,3,5-trimethyl-5-chloroindolenine or the 
like), an imidazole nucleus {an imidazole nucleus (for example 
1-alkylimidazole, 1-arylimidazole, 1-alkyl-4-phenylimidazole or the like), 
a benzimidazole nucleus (for example, 1-alkylbenzimidazole, 
1-alkyl-5-chlorobenzimidazole, 1-alkyl-5,6-dichlorobenzimidazole, 
1-alkyl-5-methoxybenzimidazole, 1-alkyl-5-cyanobenzimidazole, 
1-alkyl-5-fluorobenzimidazole, 1-alkyl-5-trifluoromethylbenzimidazole, 
1-alkyl-6-chloro-5-cyanobenzimidazole, 
1-alkyl-6-chloro-5-trifluoromethylbenzimidazole, 
1-allyl-5,6-dichlorobenzimidazole, 1-allyl-5-chlorobenzimidazole, 
1-arylbenzimidazole, 1-aryl-5-chlorobenzimidazole, 
1-aryl-5,6-dichlorobenzimidazole, 1-aryl-5-methoxybenzimidazole, 
1-aryl-5-cyanobenzimidazole or the like), a naphthimidazole nucleus (for 
example, 2-alkylnaphtho(1,2-d)imidazole, 1-arylnaphtho(1,2-d)imidazole or 
the like). In the above, each alkyl group is preferably one having 1 to 8 
carbon atoms, for example an unsubstituted alkyl group such as a methyl, 
ethyl, propyl, isopropyl, butyl or the like, a hydroxyalkyl group (for 
example, 2-hydroxyethyl or 3-hydroxypropyl or the like) or the like. A 
methyl or ethyl group is particularly preferable. In the above, each aryl 
group represents phenyl, halogen (for example, chlorine)-substituted 
phenyl, alkyl (for example, methyl)-substituted phenyl, alkoxy (for 
example, methoxy)-substituted phenyl or the like.}, a pyridine nucleus 
(for example, 2-pyridine, 4-pyridine, 5-methyl-2-pyridine, 
3-methyl-4-pyridine or the like), a quinoline nucleus {a quinoline nucleus 
(for example, 2-quinoline, 3-methyl-2-quinoline, 5-ethyl-2-quinoline, 
6-methyl-2-quinoline, 6-nitro-2-quinoline, 8-fluoro-2-quinoline, 
6-methoxy-2-quinoline, 6-hydroxy-2-quinoline, 8-chloro-2-quinoline, 
4-quinoline, 6-ethoxy-4-quinoline, 6-nitro-4-quinoline, 
8-chloro-4-quinoline, 8-fluoro-4-quinoline, 8-methyl-4-quinoline, 
8-methoxy-4-quinoline, 6-methyl-4-quinoline, 6-methoxy-4-quinoline, 
6-chloro-4-quinoline or the like), an isoquinoline nucleus (for example, 
6-nitro-1-isoquinoline, 3,4-dihydro-1-isoquinoline, 6-nitro-3-isoquinoline 
or the like) or the like}, an imidazo(4,5-b)quinoxaline nucleus (for 
example, 1,3-diethylimidazo(4,5-b)quinoxaline, 
6-chloro-1,3-diallylimidazo(4,5-b)quinoxaline or the like), an oxadiazole 
nucleus, a thiadiazole nucleus, a tetrazole nucleus, a pyrimidine nucleus 
and the like. A benzothiazole ring and a benzoxazole nuclei are 
preferable. 
R.sub.2, R.sub.3 and R.sub.7 each may take a form of a quaternary 
substituent of an arbitrary cyanine dye. 
Preferred examples of each of R.sub.2, R.sub.3 and R.sub.7 include an 
unsubstituted alkyl group having 18 or less carbon atoms (for example, a 
methyl, ethyl, propyl, butyl, pentyl, octyl, decyl, dodecyl or octadecyl 
group or the like), or a substituted alkyl group {preferably, an alkyl 
group having 18 or less carbon atoms as substituted, for example, with a 
carboxyl group, a sulfo group, a cyano group, halogen atom(s) (for 
example, fluorine, chlorine or bromine atom(s) or the like), a hydroxyl 
group, an alkoxycarbonyl group having 8 or less carbon atoms (for example, 
a methoxycarbonyl, ethoxycarbonyl, phenoxycarbonyl, or benzyloxycarbonyl 
group or the like), a substituted or unsubstituted alkoxy group having 8 
or less carbon atoms (for example, a methoxy, ethoxy, benzyloxy or 
phenethyloxy group or the like), an aryloxy group having 10 or less carbon 
atoms (for example, a phenoxy or p-tolyloxy group or the like), an acyloxy 
group having 3 or less carbon atoms (for example, an acetyloxy, or 
propionyloxy group or the like), an acyl group having 8 or less carbon 
atoms (for example, an acetyl, propionyl, benzoyl or mesyl group or the 
like), a substituted or substituted carbamoyl group (for example, a 
carbamoyl, N,N-dimethylcarbamoyl, morpholinocarbonyl, or 
piperidinocarbonyl group or the like), a substituted or unsubstituted 
sulfamoyl group (for example, a sulfamoyl, N,N-dimethylsulfamoyl, 
morpholinosulfonyl or piperidinosulfonyl group or the like), a substituted 
or unsubstituted aryl group having 10 or less carbon atoms (for example, a 
phenyl, 4-chlorophenyl, 4-methylphenyl, or .alpha.-naphthyl group or the 
like), or the like }. 
D.sub.1 and D.sub.1 ', and D.sub.2 and D.sub.2 ' each represent atomic 
groups necessary for forming an acidic nucleus as previously defined, and 
each may take a form of an acidic nucleus of various general merocyanine 
dyes. Preferably, D.sub.1 and D.sub.2 each are cyano, sulfo or carbonyl 
groups, and D.sub.1 ' and D.sub.2 ' each represent the remaining atomic 
groups necessary for forming an acidic nucleus. 
When the acidic nucleus is non-cyclic, that is, when D.sub.1 and D.sub.1 ', 
or D.sub.2 and D.sub.2 ' are mutually independent groups, terminal portion 
of the methine bond is a group such as malononitrile, 
alkylsulfonylacetonitrile, cyanomethyl benzofuranyl ketone or cyanomethyl 
phenyl ketone. 
D.sub.1 and D.sub.1 ', or D.sub.2 and D.sub.2 ' may also combine to form a 
5- or 6-membered heterocyclic ring consisting of carbon, nitrogen and 
chalcogen (typically, oxygen, sulfur, selenium and tellurium) atoms. 
Preferably, D.sub.1 and D.sub.1 ', or D.sub.2 and D.sub.2 ' combine to 
form the following nucleus: 
2-pyrazolin-5-one, pyrazolidine-3,5-dione, imidazolin-5-one, hydantoin, 
2-or 4-thiohydantoin, 2-iminooxazolidin-4-one, 2-oxazolidin-5-one, 
2-thixazolidine-2,4-dione, isoxazolin-5-one, 2-thiazolin-4-one, 
thiazolin-4-one, thiazoline-2,4-dione, rhodanine, 
thiazolidine-2,4-dithione, isorhodanine, indane-1,3-dione, thiophen-3-one, 
thiophen-3-one-1,1-dioxide, indolin-2-one, indolin-3one, indazolin-3-one, 
2-oxoindazolinium, 3-oxoindazolinium, 
5,7-dioxo-6,7-dihydrothiazolo(3,2-a)pyrimidine, cyclohexane-1,3-dione, 
3,4-dihydroisoquinolin-4-one, 1,3-dioxane-4,6-dione, barbituric acid, 
2-thiobarbituric acid, chroman-2,4-dione, indazolin-2-one or 
pyrido(1,2-a)pyrimidine-1,3-dione. 
More preferably, the nucleus is 1,3-dialkylbarbituric acid, 
1,3-dialkyl-2-thiobarbituric acid or 3-alkylrhodanine wherein each alkyl 
group is preferably an unsubstituted alkyl group). 
Preferred examples of a substituent linking to nitrogen atom(s) contained 
in the nucleus include a hydrogen atom, an alkyl group having 1 to 18, 
preferably 1 to 7 or particularly preferably 1 to 4 carbon atoms (for 
example, a methyl, ethyl, n-propyl isopropyl, n-butyl, isobutyl, hexyl, 
octyl, dodecyl or octadecyl group or the like), a substituted alkyl group 
{for example, an aralkyl group (for example, a benzyl or 2-phenylethyl 
group or the like), a hydroxyalkyl group (for example, a 2-hydroxyethyl or 
3-hydroxypropyl group or the like), a carboxyalkyl group (for example, a 
2-carboxyethyl, 3-carboxypropyl, 4-carboxybutyl or carboxymethyl group or 
the like), an alkoxyalkyl group (for example, a 2-methoxyethyl or 
2-(2-methoxyethoxy)ethyl group or the like), a sulfoalkyl group (for 
example, a 2-sulfoethyl, 3-sulfopropyl, 3-sulfobutyl, 4-sulfobutyl, 
2-(3-sulfopropoxy)ethyl, 2-hydroxy-3-sulfopropyl or 
3-sulfopropoxyethoxyethyl group or the like), a sulfatoalkyl group (for 
example, a 3-sulfatopropyl or 4-sulfatobutyl group or the like), a 
heterocyclic ring-substituted alkyl group (for example, a 
2-(pyrrolidin-2-on-1-yl)ethyl, tetrahydrofurfuryl or 2-morpholinoethyl 
group or the like), a 2-acetoxyethyl group, a carbomethoxymethyl group, a 
2-methanesulfonylaminoethyl group or the like}, an allyl group, an aryl 
group (for example, a phenyl or 2-naphthyl group or the like), an 
unsubstituted aryl group (for example, a 4-carboxyphenyl, 4-sulfophenyl, 
3-chlorophenyl or 3-methylphenyl group or the like), and a heterocyclic 
group (for example, a 2-pyridyl or 2-thiazolyl group or the like). 
Each of R.sub.4 and R.sub.5 is a substituent of a tertiary amine used in 
synthesis, and thus includes any of substituents of general tertiary 
amines. 
R.sub.4 and R.sub.5 may be the same or different, and preferably include 
unsubstituted alkyl groups each having 18 or less carbon atoms (for 
example, methyl, ethyl, propyl, butyl, pentyl, octyl, decyl, dodecyl or 
octadecyl groups or the like), or substituted alkyl groups {preferably, 
alkyl groups having 18 or less carbon atoms as substituted, for example, 
with a carboxyl group, a sulfo group, a cyano group, halogen atom(s) (for 
example, fluorine, chlorine or bromine atoms or the like), a hydroxyl 
group, an alkoxycarbonyl, aryloxycarbonyl or aralkyloxycarbonyl group 
having 8 or less carbon atoms (for example, a methoxycarbonyl, 
ethoxycarbonyl, phenoxycarbonyl or benzyloxycarbonyl group or the like), a 
substituted or unsubstituted alkoxy group having 8 or less carbon atoms 
(for example, a methoxy, ethoxy, benzyloxy or phenethyloxy group or the 
like), a monocyclic aryloxy group having 10 or less carbon atoms (for 
example, a phenoxy or p-tolyloxy group or the like), an acyloxy group 
having 3 or less carbon atoms (for example, an acetyloxy or propionyloxy 
group or the like), an acyl group having 8 or less carbon atoms (for 
example, an acetyl, propionyl, benzoyl or mesyl group or the like), a 
substituted or unsubstituted carbamoyl group (for example, a carbamoyl, 
N,N-dimethylcarbamoyl, morpholinocarbonyl or piperidinocarbonyl group or 
the like), a substituted or unsubstituted sulfamoyl group (for example, a 
sulfamoyl, N,N-dimethylsulfamoyl, morpholinosulfonyl or piperidinosulfonyl 
group or the like), a substituted or unsubstituted aryl group having 10 or 
less carbon atoms (for example, a phenyl, 4-chlorophenyl, 4-methylphenyl 
or .alpha.-naphthyl group or the like), or the like as substituent(s)}, 
cyano groups, alkoxy groups (for example, methoxy or ethoxy groups or the 
like), aryloxy groups (for example, phenoxy groups or the like), or 
alkoxycarbonyl groups (for example, ethoxycarbonyl groups or the like). 
Further, R.sub.4 and R.sub.5 may combine to form a heterocyclic ring except 
an aromatic heterocyclic ring. Preferred example of such a heterocyclic 
ring include pyrrolidine, piperidine, morpholine, piperazine, 
tetrahydropyridine, dihydropyridine, tetrahydroquinoline and the like. 
More preferred R.sub.4 and R.sub.5 are ethyl groups. 
Preferred examples of a heterocyclic ring formed containing Q.sub.2 include 
a pyrrole nucleus, a carbazole nucleus, an indole nucleus, a pyrazole 
nucleus, a pyrazolo(1,5-a)benzimidazole nucleus, a 
pyrazole(1,5-b)quinazolone nucleus, an indazole nucleus and the like. 
A 5- or 6-membered heterocyclic ring formed containing W.sub.1 or W.sub.2 
is one represented by removing an oxo group or a thioxo group at an 
appropriate position of a heterocyclic ring formed containing D.sub.1 and 
D.sub.1 ', or D.sub.2 and D.sub.2 '. 
Preferred R.sub.6 and R.sub.8 are identical to examples of the 
substituent(s) previously stated as those linking to nitrogen atom(s) 
contained in the nucleus of a heterocyclic ring formed containing D.sub.1 
and D.sub.1 ', or D.sub.2 or D.sub.2 '. 
Ar represents an aromatic group, and is preferably a substituted or 
unsubstituted aryl group (for example, a phenyl, 3-chlorophenyl or 
naphthyl group or the like). 
Each of L.sub.1, L.sub.2, L.sub.3, L.sub.4, L.sub.5, L.sub.6, L.sub.7, 
L.sub.8, L.sub.9, L.sub.10, L.sub.11, L.sub.12, L.sub.13, L.sub.14, 
L.sub.15, L.sub.16, L.sub.17 L.sub.18, L.sub.19, L.sub.20, L.sub.21, 
L.sub.22, L.sub.23, L.sub.24, L.sub.25, L.sub.26, L.sub.27, L.sub.28, 
L.sub.29, L.sub.30, L.sub.31, L.sub.32, L.sub.33 and L.sub.34 represents a 
methine group {which may optionally be substituted with a substituted or 
unsubstituted alkyl group (for example, a methyl or ethyl group or the 
like), a substituted or unsubstituted aryl group (for example, a phenyl 
group or the like) or a halogen atom (for example, a chlorine or bromine 
atom or the like)}, or alternatively may form a ring together with another 
methine group or an auxochrome. 
Specific examples of methine dyes used in the present invention are 
illustrated below, but the scope of the present invention should not be 
interpreted to be limited thereto. 
Examples of compounds represented by the general formula (II): 
__________________________________________________________________________ 
##STR12## 
Compound 
Y Z V.sub.1 
Z' R.sub.2 
l.sub.1 
M m 
__________________________________________________________________________ 
(1) N NCH.sub.3 
H S C.sub.2 H.sub.5 
0 I.sup.- 1 
(2) N NCH.sub.3 
SCH.sub.3 
S C.sub.2 H.sub.5 
0 I.sup.- 1 
(3) N NCH.sub.3 
Cl S C.sub.2 H.sub.5 
0 I.sup.- 1 
(4) N NCH.sub.3 
OCH.sub.3 
S C.sub.2 H.sub.5 
0 I.sup.- 1 
(5) N NCH.sub.3 
##STR13## 
S C.sub.2 H.sub.5 
0 I.sup.- 1 
(6) N NC.sub.2 H.sub.5 
SCH.sub.3 
NC.sub.2 H.sub.5 
C.sub.2 H.sub.5 
0 I.sup.- 1 
(7) N NCH.sub.3 
SCH.sub.3 
O C.sub.2 H.sub.5 
0 I.sup.- 1 
(8) N N(CH.sub.2).sub.4 SO.sub.3.sup.- 
##STR14## 
O CH.sub.2 CO.sub.2 H 
0 -- -- 
(9) N NCH.sub.3 
##STR15## 
Se C.sub.2 H.sub.5 
1 
##STR16## 1 
(10) N NCH.sub.3 
SCH.sub.3 
S C.sub.2 H.sub.5 
1 I.sup.- 1 
(11) N NCH.sub.3 
H NCH.sub.3 
CH.sub.3 
2 I.sup.- 1 
(12) N NCH.sub.3 
OCH.sub.3 
S CH.sub.3 
3 I.sup.- 1 
(13) N S SCH.sub.3 
O C.sub.2 H.sub.5 
0 I.sup.- 1 
(14) N O H S CH.sub.3 
1 I.sup.- 1 
(15) N Se H Se CH.sub.3 
1 I.sup.- 1 
(16) N NCH.sub.3 
Cl 
##STR17## 
CH.sub.3 
2 ClO.sub. 4.sup.- 
1 
(17) CH NCH.sub.3 
Cl S C.sub.2 H.sub.5 
3 I.sup.- 1 
(18) CH O Cl S C.sub.2 H.sub.5 
0 I.sup.- 1 
(19) CH S Cl O C.sub.2 H.sub.5 
0 Br.sup.- 1 
(20) 
##STR18## 
(21) 
##STR19## 
__________________________________________________________________________ 
##STR20## 
Compound V.sub.1 Z Y.sub.1 Y.sub.2 
__________________________________________________________________________ 
(22) 
##STR21## O OCH.sub.3 
OCH.sub.3 
(23) SCH.sub.3 S CH.sub.3 CH.sub.3 
(24) H NC.sub.2 H.sub.5 
CH.sub.3 H 
(25) 
##STR22## S NO.sub.2 H 
(26) H S Cl Cl 
__________________________________________________________________________ 
##STR23## 
Compound V.sub.1 R.sub.1 
Z R.sub.2 l.sub.1 
M m 
__________________________________________________________________________ 
(27) SCH.sub.3 
CH.sub.3 
S C.sub.2 H.sub.5 
0 I.sup.- 
1 
(28) SCH.sub.3 
(CH.sub.2).sub.3 SO.sub.3.sup.- 
S 
##STR24## 0 -- -- 
(29) 
##STR25## 
CH.sub.2 CO.sub.2 H 
O C.sub.2 H.sub.4 OCH.sub.3 
1 Cl.sup.- 
1 
(30) 
##STR26## 
CH.sub.3 
Se C.sub.2 H.sub.5 
2 I.sup.- 
1 
(31) 
##STR27## 
(32) 
##STR28## 
(33) 
##STR29## 
__________________________________________________________________________ 
Examples of compounds represented by the general formula (III): 
__________________________________________________________________________ 
##STR30## 
Compound 
Y Z V.sub.1 
l.sub.2 
M m Heterocyclic ring 
__________________________________________________________________________ 
(34) N NCH.sub.3 
##STR31## 
1 I.sup.- 1 
##STR32## 
(35) N NC.sub.2 H.sub.5 
SCH.sub.3 
1 Br.sup.- 1 
##STR33## 
(36) N NCH.sub.3 
Cl 1 
##STR34## 1 
##STR35## 
(37) N N(CH.sub.2).sub.4 SO.sub.3.sup.- 
OCH.sub.3 
1 -- -- 
##STR36## 
(38) N NCH.sub.3 
##STR37## 
1 I.sup.- 1 
##STR38## 
(39) N O SCH.sub.3 
1 I.sup.- 1 
##STR39## 
(40) N NCH.sub.3 
##STR40## 
1 Br.sup.- 1 
##STR41## 
(41) 
##STR42## 
(42) 
##STR43## 
__________________________________________________________________________ 
Examples of compounds represented by the general formula (IV): 
__________________________________________________________________________ 
Compound 
Y Z V.sub.1 l.sub.3 
M m 
__________________________________________________________________________ 
##STR44## 
(43) N NCH.sub.3 H 0 I.sup.- 1 
(44) N NCH.sub.3 SCH.sub.3 
0 I.sup.- 1 
(45) N NCH.sub.3 SCH.sub.3 
1 I.sup.- 1 
(46) N N(CH.sub.2).sub.3 SO.sub.3.sup.- 
##STR45## 
0 Na.sup.+ 
1 
(47) N S 
##STR46## 
1 Br.sup.- 
1 
(48) N O SCH.sub.3 
1 Br.sup.- 
1 
##STR47## 
(49) N NCH.sub.3 SCH.sub.3 
0 I.sup.- 1 
(50) N NCH.sub.3 SCH.sub.3 
1 I.sup.- 1 
(51) N N(CH.sub.2).sub.4 SO.sub.3.sup.- 
##STR48## 
0 HN.sup.+ (C.sub.2 H.sub.5).sub.3 
1 
(52) N NCH.sub.3 
##STR49## 
1 CF.sub.3 SO.sub.3.sup.- 
1 
(53) N NCH.sub.2 CO.sub.2 H 
H 1 Cl.sup.- 
1 
(54) 
##STR50## 
(55) 
##STR51## 
(56) 
##STR52## 
__________________________________________________________________________ 
Examples of compounds represented by the general formula (V): 
__________________________________________________________________________ 
Compound 
Y Z V.sub.1 
l.sub.4 
M m Acidic nucleus 
__________________________________________________________________________ 
##STR53## 
(57) N NCH.sub.3 
H 0 -- -- 
##STR54## 
(58) N NCH.sub.3 
SCH.sub.3 
0 -- -- 
##STR55## 
(59) N NCH.sub.3 
SCH.sub.3 
0 -- -- 
##STR56## 
(60) N NCH.sub.3 
SCH.sub.3 
1 -- -- 
##STR57## 
(61) N NC.sub.2 H.sub.5 
##STR58## 
2 -- -- 
##STR59## 
(62) N N(CH.sub.2).sub.3 SO.sub.3.sup.- 
H 1 Na.sup.+ 
1 
##STR60## 
(63) N S SCH.sub.3 
2 K.sup.+ 
1 
##STR61## 
(64) N NCH.sub.3 
SCH.sub.3 
0 -- -- 
##STR62## 
(65) N NCH.sub.3 
##STR63## 
0 -- -- 
##STR64## 
(66) N NC.sub.2 H.sub.5 
H 0 -- -- 
##STR65## 
##STR66## 
(67) N NCH.sub.3 
H 0 -- -- 
##STR67## 
(68) N NCH.sub.3 
##STR68## 
1 -- -- 
##STR69## 
(69) N NC.sub.2 H.sub.5 
SCH.sub.3 
1 -- -- 
##STR70## 
(70) N NC.sub.2 H.sub.5 
H 1 -- -- 
##STR71## 
(71) N S H 2 -- -- 
##STR72## 
(72) N NCH.sub.3 
##STR73## 
0 -- -- 
##STR74## 
(73) N NC.sub.2 H.sub.5 
H 1 -- -- 
##STR75## 
__________________________________________________________________________ 
Examples of compounds represented by the general formula (VI): 
__________________________________________________________________________ 
Compound 
Y Z V.sub.1 
R.sub.4 
R.sub.5 
M m 
__________________________________________________________________________ 
##STR76## 
(74) N NCH.sub.3 
##STR77## 
C.sub.2 H.sub.5 
C.sub.2 H.sub.5 
I.sup.- 
1 
(75) N NCH.sub.3 
SCH.sub.3 
C.sub.2 H.sub.5 
C.sub.2 H.sub.5 
I.sup.- 
1 
(76) N NC.sub.2 H.sub.5 
H (CH.sub.2).sub.2 O(CH.sub.2).sub.2.sup.- 
Br.sup.- 
1 
##STR78## 
(77) N NCH.sub.3 
SCH.sub.3 
C.sub.2 H.sub.5 
C.sub.2 H.sub.5 
I.sup.- 
1 
(78) N N(CH.sub.2).sub.4 SO.sub.3.sup.- 
##STR79## 
(CH.sub.2).sub.4 
-- -- 
(79) N S SCH.sub.3 
(CH.sub.2).sub.5 
I.sup.- 
1 
__________________________________________________________________________ 
Examples of compounds represented by the general formula (VII): 
##STR80## 
Examples of compounds represented by the general formula (VIII): 
##STR81## 
Examples of compounds represented by the general formula (IX): 
##STR82## 
Synthetic processes of dyes used in the present invention are basically 
classified into the following two categories. 
In the first synthetic process, a heteroazulene nucleus having a positive 
charge is used as a starting substance. A carbon atom in the heteroazulene 
nucleus having a positive charge (carbocation) is attacked by a 
nucleophilic agent. By selecting a suitable nucleophilic agent, a methine 
dye having a methine bond at the carbon atom which was nucleophilically 
attacked may be obtained. 
In the second synthetic process, a heteroazulene nucleus having a positive 
charge, at least one carbon atom of which has a methyl substituent is used 
as a starting substance. This methyl-substituted part is deprotonized with 
a base to form a carbon atom having a negative charge (carbanion), which 
is then attacked by an electrophilic agent. A methine dye having a methine 
bond at the methyl-substituted part is obtained by selecting a proper 
electrophilic agent. 
Though many heteroazulene nuclei are usable for the present invention, 
those which can readily be synthesized and are particularly useful include 
a cycloheptofuran nucleus, a cycloheptothiophene, a cycloheptopyrrole 
nucleus, a cycloheptoxazole nucleus, a cycloheptothiazole nucleus, a 
cycloheptimidazole nucleus, a cycloheptopyrazole nucleus, a 
cycloheptotriazole nucleus and the like, as disclosed in D. Ginsburg, 
Non-Benzenoid Aromatic Compounds, Chapter VII, pages 434 to 446, 
Interscience Publishers (1959). 
As methods for giving each nucleus a positive charge, there is a method 
where a nitrogen atom is quaternarized when the nucleus has nitrogen 
atom(s), a method by an oxidation reaction when the nucleus does not have 
any nitrogen atom, and the like.

Explanation is made below on a cycloheptimidazole nucleus as a particularly 
preferred example. 
(SYNTHETIC METHOD 1) 
A methine dye of the present invention represented by the general formula 
(XII) may be prepared by condensing a cycloheptimidazolium ion represented 
by the general formula (X) with a precursor of auxochrome and methine bond 
as represented by the general formula (XI): 
##STR83## 
wherein G represents one of the formulae (XIII) and (XIV): 
##STR84## 
In the formulae (XIII) and (XIV), R.sub.2, Q.sub.1, L.sub.4 and L.sub.5 
have the same meanings as those in the general formula (II), respectively, 
and D.sub.1, D.sub.1 ', L.sub.16 and L.sub.17 have the same meanings as 
those in the general formula (V), respectively. 
In the formulae (X) and (XII), R.sub.1, V.sub.1 to V.sub.5, M and m have 
the same meanings as those in the general formula (I), respectively. 
X.sup.- in the formula (X) represents an anion, and r represents a number 
necessary for neutralizing the charge of a compound represented by the 
formula (X). 
Examples of an anion represented by X.sup.- are preferably those previously 
mentioned as examples of an anion of a charge balance counter ion M, 
particularly preferably a trifluoromethanesulfonate ion. 
In the formula (X), T represents a hydrogen atom or an eliminable group 
generally used in organic synthetic chemistry, for example an eliminable 
group disclosed in Jerry March, "Advanced Organic Chemistry: Reactions, 
Mechanism and Structure", published by McGraw-hill Kogakusha (1977), pages 
265 to 452. Preferred examples of such as elimiable group are halogen 
atoms (for example, chlorine, bromine or iodine atoms or the like), 
alkylthio groups (for example, ethylthio groups or the like), alkoxy 
groups (for example, methoxy groups or the like) and alkylsulfonyl groups 
(for example, methylsulfonyl groups or the like). A particularly preferred 
T group is a hydrogen atom. 
q in the formulae (XI) and (XII) is 0 or 1. 
The bonding position of T and the methine group in the formulae (X) and 
(XII) may be any of the 4-, 5-, 6-, 7- and 8-positions, as is in the 
general formula (I). 
A compound of the formula (XI) wherein G represents a formula (XIII) and q 
is 1 is a methyl quaternary compound, and is used as a starting substance 
for the corresponding methylene base. 
Reactions for condensing bases are well known techniques for the 
preparation of monomethinecyanine dyes. Such reactions are disclosed in T. 
H. James, The Theory of The Photographic Process, 4th edition, Macmillan, 
1977, Chapter 8, page 206. 
For condensation of a methylene base for preparing a cyanine dye, it is 
necessary for each of the two basic nuclei to be reacted to contain a 
reactive substance, and it has been found that a cycloheptimidazolium ion 
of the formula (X) comes under nucleophilic attack at a 7-membered carbon 
atom. The reaction is liable to occur at the 4-, 6- or 8-position, 
particularly at the 4- on 6-position depending or the electronic state. 
Thus, a condensation reaction of a methylene base and an activated 
cycloheptimidazolium ion can be carried out through a methylene base 
condensation reaction according to general methods used for the 
preparation of cyanine dyes. 
Similarly, a compound of the formula (XI) wherein q is 0 and G is a group 
represented by the formula (XIV), which is a ketomethylene or a 
cyanomethylene, is condensed with an activated cycloheptimidazolium ion to 
form a merocyanine-like dye. As for the reaction position, there is the 
same tendency as in the above cyanine-like dye synthesis. That is, the 
reaction is liable to occur at the 4-, 6- or 8-position, particularly at 
the 4- or 6-position. Condensation reaction of a ketomethylene or a 
cyanomethylene with an activated cycloheptimidazolium ion may be carried 
out according to general methods used in preparation of merocyanine dyes. 
Methods used for the preparation of cyanine dyes or merocyanine dyes may 
also be used for a condensation reaction of a compound of the formula (X) 
with a compound of the formula (XI). The condensation reaction may be 
carried out at room temperature or may be accelerated with heating. 
Examples of usable reaction solvent(s) include acetonitrile, aliphatic or 
aromatic hydrocarbons or halogenated derivatives thereof such as benzene, 
toluene, xylene or decane; ether; pyridine; dimethylsulfoxide; 
dimethylformamide; and alcohols such as methanol and ethanol. 
Acetonitrile, pyridine, dimethylformamide, methanol and ethanol are 
particularly preferable. 
For condensation using a methylene base, an organic base, for example a 
tertiary amine (for example, triethylamine, 
1,8-diazabicyclo(5,4,0)-7-undecene (DBU) or the like), 
tetramethylguanidine or piperidine is used. 
The first synthetic method for dyes used in the invention is useful for the 
preparation of a methine dye wherein a cycloheptimidazole nucleus is 
connected with a basic nucleus of a type found in cyanine dyes through one 
methine group, or a methine dye wherein a cycloheptimidazole nucleus is 
directly connected with an acidic nucleus of a type found in merocyanine 
dyes. Thus, methine dyes prepared by the first synthetic method are 
monomethine dyes of the general formula (II) and zeromethine dyes of the 
general formula (V). 
A cycloheptimidazole nucleus symmetry monomethine or trimethyne dye may be 
synthesized by the reaction of a compound of the formula (X) with a 
malonic acid or a glutaconic acid (this method is similar to the first 
synthetic method) by applying a synthetic method disclosed in F. M. Hamer, 
Heterocyclic Compounds-Cyanine Dyes and Related Compounds, Chapter 2, 
pages 72 and 73, Chapter 4, page 111, John Wily and Sons Company (1964). 
According to the synthetic method, monomethine and trimethine dyes of the 
general formula (IV) may be synthesized. The reaction is liable to occur 
at the 4- or 6-position, particularly at the 4-position of the 
cycloheptimidazolium ion. 
A method for synthesizing hemicyanine type dyes of the general formula (VI) 
as a special synthetic method similar to the first synthetic method is 
described below. 
A dimethinehemicyanine type dye represented by the general formula (VI) may 
be synthesized by condensing a compound of the formula (X) with a tertiary 
amine having at least one ethyl group. 
The reaction is liably to occur at the 4-, 6- or 8-position, particularly 
at the 4-position. 
(SYNTHETIC METHOD 2) 
The second synthetic method makes possible the synthesis of methine dyes 
each containing 2 or more methine groups which connect a 
cycloheptimidazole nucleus with the remaining basic or acidic nucleus. 
Methine dyes which can be synthesized according to the second method are 
represented by the following formula (XV): 
##STR85## 
Such a dye may be prepared by condensing a compound represented by the 
formula (XVI). 
##STR86## 
with a compound represented by the formula (XVII) 
##STR87## 
and then condensing the condensation product with a compound represented 
by the formula (XVIII) 
##STR88## 
In the formulae, Ar.sup.1 and Ar.sup.2 are carbon ring aromatic groups, 
and G and G' each represent groups represented by the formula (XIX), 
(XIII) or (XIV): 
##STR89## 
wherein R.sub.1 and V.sub.1 to V.sub.5 have the same meanings as those in 
the general formula (I), respectively, and X.sup.- and r have the same 
meanings as those in the formula (X), respectively. 
When G and G' in the formulae (XVII) and (XVIII) satisfy the formula (XIX), 
q and q' are 1, and at that time the bonding position of the methyl group 
may be any of the 4-, 5-, 6-, 7- and 8-positions, but preferably may be 
the 4-, 6- or 8-position, more preferably the 4- or 6-position. 
Further, L.sub.35, L.sub.36 and L.sub.37 in the formulae (XV), (XVI), 
(XVII) and (XVIII) represent optionally substituted methine groups, and 
each have the same meanings as L.sub.1, L.sub.2, L.sub.3, L.sub.4 and 
L.sub.5 in the general formula (II). 
q and q' are 0 or 1, and p is 0 or a positive integer and typically 0, 1, 2 
or 3. At least one of G and G' represents the formula (XIX). 
As apparent from the foregoing, a starting substance necessary for the 
second synthetic method of dyes used in the invention is a 
cycloheptimidazolium ion having a methyl substituent. 
When a methine dye having only one cycloheptimidazole nucleus is 
synthesized, a compound of the formula (XVII) or (XVIII) wherein one of G 
and G' is represented by the formula (XVIII) or (XIV) is used. 
A compound necessary as the remaining starting substance is that of the 
formula (XVI). When p is 0 and L.sub.15 is --CH--, a compound of the 
formula (XVI) is apparently a diarylformamidine, typically 
diphenylformamidine. When p is a positive integer, a compound of the 
formula (XVI) obtained is an analog of a diarylformamidine or a vinylog. 
A compound obtained by the reaction of an analog of a diarylformamidine or 
vinylog represented by the formula (XVI) with a compound of the formula 
(XVII) wherein G satisfies one of the formula (XIII) or (XIV) is an 
intermediate generally used for preparation of a cyanine dye or a 
merocyanine dye. 
Though these intermediates are often used as such, their reactivities can 
be increased by acyl substitution of the N-hydrogen, for example by 
reaction with a carboxylic acid or an arhydride thereof. 
Acetyl-substituted intermediates are most generally used. When these 
intermediates each contain a quaternary ammonium nucleus as represented by 
the formula (XIII), they are often called I.C.I. intermediates. On the 
other hand, when these intermediates each contain a ketomethylene or 
cyanomethylene as represented by the formula (XIV), they are often called 
Dains intermediates. The methods using I.C.I. intermediates and Dains 
intermediates in the synthesis of cyanine dyes and merocyanine dyes are 
disclosed in T. H. James, The Theory of the Photographic Process pages 195 
to 212 which is previously cited. 
A new intermediate for the preparation of dyes is obtained by reacting an 
analog of a diarylformamidine or vinylog represented by the formula (XVI) 
with a compound of the formula (XVII) wherein G satisfies the formula 
(XIX). The obtained dye intermediate containing a cycloheptimidazole 
nucleus can be used similarly to an I.C.I. intermediate and a Dains 
intermediate known in the preparation of a methine dye. 
A dye intermediate obtained by reacting a compound of the formula (XVI) 
with a compound of the formula (XVII), and if necessary acylacting the 
product can be represented by the formula (XX): 
##STR90## 
wherein R.sub.9 represents hydrogen or acyl, and the remaining symbols are 
as previously defined. 
A dye of the formula (XV) can be synthesized by condensing a compound of 
the formula (XVIII) with a dye intermediate of the formula (XX). The order 
of whole reactions from a starting substance to a final dye is similar to 
that in synthesis known in the preparation of a cyanine dye and a 
merocyanine dye, except for a methyl-substituted cycloheptimidazolium ion. 
Though the reaction generally progresses at room temperature, the reaction 
may be promoted according to necessity with heating. The reaction may also 
be carried out in the same solvent as that used in the aforementioned 
first synthetic method of a dye of the invention. 
The second synthetic method is more useful than the first synthetic method 
in that a larger number of methine groups can be introduced in the dye and 
in that the substitution position of methine bond in the 
cycloheptimidazole nucleus is not arbitrary and the amount of by-products 
is small. Substituted or unsubstituted methine group(s) of a necessary 
number may be introduced according to the second synthetic method. 
Since absorption of a dye having 1 or 2 or more cycloheptimidazole nuclei 
shifts to a deep color, it is in fact seldom necessary for obtaining 
absorption of a dye of long wavelength that p in the formula (XV) exceeds 
3. 
Though the above explanation was made citing as methine sources analogs of 
diarylformamidines or vinylogs represented by the formula (XVI), other 
methine sources, for example analogs of orthoesters or vinylogs may of 
course be used. 
Methine dyes of the general formulae (II), (III), (IV), (V), (VI) and (IX) 
may be synthesized using the second synthetic method. 
Further, methine dyes of the general formulae (VII) and (VIII) may be 
synthesized according to the first and second synthetic methods and F. M. 
Hamer, Heterocyclic Compounds-Cyanine Dyes and Related Compounds, John 
Wily and Sons Company (1964). 
Compounds which satisfy the formulae (X) and (XIX) are cycloheptimidazolium 
ions as starting substances in the first and second synthetic methods, and 
synthesis of 
(X): R.sub.1 =CH.sub.3, V.sub.1 =SCH.sub.3, V.sub.2 to V.sub.5 =H, T=H 
(XIX): R.sub.1 =CH.sub.3, V.sub.1 =SCH.sub.3, V.sub.2 to V.sub.5 =H 
as representative examples thereof is explained below. 
2-Hydroxy-2,4,6-cycloheptatrien-1-one readily obtained according to a 
method disclosed in Journal of the American Chemical Society, vol. 37, No. 
22, pages 5257 to 5259 (1965), or 
2-hydroxy-5-methyl-2,4,6-cycloheptatrien-1-one readily obtained according 
to the method disclosed in Bulletin of the Chemical Society of Japan, vol. 
32, pages 493 to 496 (1959) is 0-methylated with a methylating agent (for 
example, dimethyl sulfate) to obtain 2-methoxy-2,4,6-cycloheptatrien-1-one 
or 2-methoxy-5-methyl-2,4,6-cycloheptatrien-1-one, respectively, which is 
then condensed with thiourea to obtain 2-mercaptocycloheptimidazole or 
2-mercapto-6-methylcycloheptimidazole, respectively. They are then each 
S-methylated with a methylating agent (for example, methyl iodide) to 
obtain 2-methylthiocycloheptimidazole or 
6-methyl-2-methylthiocycloheptimidazole, respectively. 
They are further each N-methylated with a methylating agent (for example, 
methyl trifluoromethanesulfonate) to obtain 
3-methyl-2-methylthiocycloheptimidazolium ion or 
3,6-dimethyl-2-methylthiocycloheptimidazolium ion. 
The above overall scheme is as follows: 
##STR91## 
(SYNTHETIC EXAMPLE) 
Synthetic examples of the above dyes are exhibited below. 
SYNTHETIC EXAMPLE 1: SYNTHESIS OF (2) 
Synthesis of (2) is stated successively starting from synthesis of a raw 
material of the dye. 
(a) Synthesis of 2-methoxy-2,4,6-cycloheptatrien-1-one 
First, 200 g of 2-hydroxy-2,4,6-cycloheptatrien-1-one which is readily 
obtained according to the method disclosed in Journal of the American 
Chemical Society, vol. 87, No. 22, pages 5257 to 5259 (1965) and 340 g of 
potassium carbonate were added to 1.3 l of acetone containing 10% water, 
310 g of dimethyl sulfate was added thereto and the mixture was refluxed 
with heating for 8 hours. After the mixture was allowed to stand 
overnight, deposited inorganic matters were filtered out and acetone was 
distilled away from the filtrate under reduced pressure. Then, 1 l of 
water was added to the concentrate, followed by extraction with chloroform 
(0.3 l.times.3). The chloroform layer was dried over anhydrous sodium 
sulfate, concentrated to evaporate the solvent and then distilled under 
reduced pressure (120.degree. C./0.5 mmHg). 
Colorless liquid 205.7 g (Yield 92.3%). 
(b) Synthesis of 2-mercaptocycloheptimidazole 
According to the method disclosed in Journal of the American Chemical 
Society, vol. 76, pages 3352 and 3353 (1954), 150 g of 2-methoxytropone 
and 84 g of thiourea were added to 255 g of a solution of 28% sodium 
methoxide in methanol, and stirred at room temperature for 30 minutes. 
Further, 600 ml of methanol was added thereto and acetic acid was added 
until the pH of the solution becomes around 5. Deposited crystals were 
filtered and washed with methanol. The obtained crystals were added to 1 l 
of methanol, and refluxed with heating for 30 minutes. After being allowed 
to cool to room temperature, the crystals were filtered and dried. 
Yellow crystals 125 g (Yield 70.0%), Melting point 300.degree. C. or more. 
(c) Synthesis of 2-methylthiocycloheptimidazole 
First, 38 g of potassium hydroxide was dissolved in 800 ml of methanol, 100 
g of 2-mercaptocycloheptimidazole was added thereto, and the mixture was 
stirred with heating to the inner temperature of about 45.degree. C. Then, 
131.2 g of dimethyl sulfate was added dropwise thereto and stirred with 
heating to the inner temperature of about 45.degree. C. for one hour. 
After the solvent was distilled away to some extent under reduced 
pressure, 1 l of water was added and extracted with chloroform (0.5 
l.times.2). After being dried over anhydrous sodium sulfate, the 
chloroform layer was evaporated under reduced pressure to 200 ml, and 1 l 
of hexane was added thereto to deposit crystals, which were the filtered 
and dried. 
Colorless crystals 89 g (Yield 82.0%), Melting point 101.degree. to 
102.degree. C. 
(d) Synthesis of 3-methyl-2-methylthiocycloheptimidazolium 
trifluoromethansulfonate 
First, 25 g of 2-methylthiocycloheptimidazole was added to 100 ml of 
anisole, and stirred under ice cooling. Then, 28 g of methyl 
trifluoromethanesulfonate was added dropwise and stirred under ice 
cooling. The mixture was further stirred at room temperature for 2 hours 
and 30 minutes, 200 ml of ethyl acetate was added thereto, and deposited 
crystals were filtered and dried. 
Colorless crystals 39.7 g (Yield 82.0%), Melting point 163.degree. to 
164.degree. C. 
(e) Synthesis of (2) 
First, 2.8 g of 3-methyl-2-methylthiocycloheptimidazolium 
trifluoromethanesulfonate and 2.3 g of 3-methyl-2-methylbenzothiazolium 
p-toluenesulfonate were added to 50 ml of acetonitrile, 2.3 ml of 
triethylamine was further added, and the mixture was refluxed with heating 
for one hour. After the solvent was distilled away under reduced pressure, 
the mixture was subjected to purification by silica gel column 
chromatography using a mixed solvent of methanol/chloroform=1/4 as a 
developing solvent. The obtained crystals were added to 50 ml of methanol 
and heated to dissolve it. The insoluble matters were filtered out during 
hot state, a solution of 1.2 g sodium iodide in 5 ml of methanol was added 
to the filtrate, and the mixture was allowed to cool. Deposited crystals 
were filtered, washed with methanol and water, and dried. 
Purple crystals 0.75 g (Yield 24%), Melting point 260.degree. to 
264.degree. C., .lambda.max=574 nm (.epsilon.=9.95.times.10.sup.4) 
(solvent methanol). 
As by-product dyes in the synthesis of (2), slight amounts of dyes having a 
methine bond at the 4-position and the 8-position of the 
cycloheptimidazole nucleus, respectively are obtained. 4-position: 
Compound (27), 8-position: Compound (32). 
Slight amounts of similar by-product dyes were also obtained in the 
following synthetic examples 2, 3, 4, 5, 6, 7, 8, 9 and 10 according to 
the first synthetic method. 
SYNTHETIC EXAMPLE 2: SYNTHESIS OF (7) 
First, 4 g of 3-methyl-2-methylthiocycloheptimidazolium 
trifluoromethanesulfonate as synthesized in Synthetic example 1 (d) and 
3.53 g of 3-ethyl-2-methylbenzoxazolium p-toluenesulfonate were added to 
50 ml of acetonitrile, 3 ml of triethylamine was further added, and the 
mixture was refluxed with heating for one hour. Then, 200 ml of ethyl 
acetate was added to the reaction solution and the deposited crystals were 
collected by filtration. The crystals were added to 100 ml of methanol and 
dissolved therein with heating. The insoluble matters were filtered out in 
a hot state, and a solution of 1.5 g of sodium iodide in 5 ml of methanol 
was added to the filtrate and allowed to cool. Deposited crystals were 
collected by filtration, washed with methanol and water, and dried. 
Purple crystals 1.8 g (Yield 36%), Melting point 300.degree. C. or more, 
.lambda.max=547 nm (.epsilon.=1.05.times.10.sup.5) (methanol). 
SYNTHETIC EXAMPLE 3: SYNTHESIS OF (58) 
First, 3 g of 3-methyl-2-methylthiocycloheptimidazolium 
trifluoromethanesulfonate as synthesized in Synthetic example 1 (d) and 
1.77 g of N,N-diethylthiobarbituric acid were added to 30 ml of pyridine, 
and stirred with heating to the inner temperature of 50.degree. C. for 30 
minutes. Then, 200 ml of ethyl acetate was added to the reaction solution 
and deposited crystals were collected by filtration. The crystals were 
added to a mixed solvent of methanol (100 ml)/chloroform (200 ml) and 
dissolved therein under reflux with heating. The insoluble matters were 
filtered out in hot state, and the filtrate was concentrated to 120 ml 
under reduced pressure. After being allowed to stand at room temperature, 
the obtained crystals were collected by filtration, washed with methanol 
and dried. Red crystals 1 g (Yield 29.2%), Melting point 300.degree. C. or 
more, .lambda.max=530 nm (.epsilon.=5.18.times.10.sup.4) (methanol). 
SYNTHETIC EXAMPLE 4: SYNTHESIS OF (59) 
First, 3 g of 3-methyl-2-methylthiocycloheptimidazolium 
trifluoromethanesulfonate as synthesized in Synthetic example 1 (d) and 
2.1 g of N,N-di-n-butylbarbituric acid were added to 30 ml of pyridine, 
and stirred with heating to the inner temperature of 50.degree. C. for one 
hour. Then, 200 ml of water was added to the reaction solution and 
deposited crystals were collected by filtration. The crystals were 
dissolved in a mixed solvent of isopropanol (100 ml)/chloroform (100 ml), 
the insoluble matters were filtered out, and the filtrate was concentrated 
to 100 ml under reduced pressure. After being allowed to stand at room 
temperature, deposited crystals were collected by filtration, washed with 
isopropanol and dried. 
Red crystals 1.06 g (Yield 28.0%), Melting point 219.degree. to 221.degree. 
C., .lambda.max=516 nm (.epsilon.=4.59.times.10.sup.4) (methanol). 
SYNTHETIC EXAMPLE 5: SYNTHESIS OF (49) 
First, 5 g of 3-methyl-2-methylthiocycloheptimidazolium 
trifluoromethanesulfonate as synthesized in Synthetic example 1 (d) and 
0.84 g of malonic acid were added to 50 ml of pyridine, and refluxed with 
heating for 30 minutes. Then, 200 ml of water was added to the reaction 
solution, followed by addition of 2.2 g of sodium iodide. Deposited 
crystals were collected by filtration, and purified by silica gel column 
chromatography using a mixed solvent of methanol/chloroform=1/4 as a 
developing solvent. The resulting crystals were dissolved in a mixed 
solvent of methanol (50 ml)/chloroform (50 ml) and the insoluble matters 
were filtered out. The filtrate was concentrated to 60 ml and allowed to 
cool. Deposited crystals were collected by filtration, washed with 
methanol and dried. 
Purple crystals 1.1 g (Yield 14.4%), Melting point 300.degree. C. or more, 
.lambda.max=674 nm (.epsilon.=6.49.times.10.sup.4) (methanol). 
SYNTHETIC EXAMPLE 6: SYNTHESIS OF (50) 
First, 10 g of 3-methyl-2-methylthiocycloheptimidazolium 
trifluoromethanesulfonate as synthesized in Synthetic example 1 (d) and 
3.82 g of glutaconic acid were added to 50 ml of pyridine, and stirred 
with heating to the inner temperature of 50.degree. C. for one hour. Then, 
200 ml of ethyl acetate was added to the reaction solution, and deposited 
crystals were collected by filtration. The crystals were dissolved in 1 of 
methanol under reflux with heating and the insoluble matters were filtered 
out. Then, a solution of 1 g of sodium iodide in 50 ml of methanol was 
added to the filtrate, and concentrated to 200 ml. Deposited crystals were 
collected by filtration, washed with methanol and water, and dried. 
Deep purple crystals 2 g (Yield 12.5%), Melting point decomposed at about 
200.degree. C., .lambda.max=774 nm (.epsilon.=1.14.times.10.sup.5) 
(methanol). 
SYNTHETIC EXAMPLE 7: SYNTHESIS OF (77) 
First, 3 g of 3-methyl-2-methylthiocycloheptimidazolium 
trifluoromethanesulfonate as synthesized in Synthetic example 1 (d) was 
added to 30 ml of acetonitrile, 1.5 ml of triethylamine was further added, 
and the mixture was stirred with heating to the inner temperature of 
60.degree. C. for one hour. After the reaction, the solvent was distilled 
away, and the resulting crystals were purified by silica gel column 
chromatography using a mixed solvent of methanol/chloroform=1/4 as a 
developing solvent. The resulting crystals were dissolved in 10 ml of 
methanol, and a solution of 0.7 g of sodium iodide in 3 ml of methanol was 
added. After further addition of 100 ml of water, deposited crystals were 
collected by filtration, washed with methanol and dried. 
Red crystals 0.5 g (Yield 13.7%), Melting point 219.degree. to 221.degree. 
C., .lambda.max=522 nm (.epsilon.=8.12.times.10.sup.4) (methanol). 
SYNTHETIC EXAMPLE 8: SYNTHESIS OF (4) 
Synthesis of (4) is stated below successively from synthesis of a raw 
material of the dye. 
(a) Synthesis of 2-methoxycycloheptimidazole 
First, 3 g of 2-methylthiocycloheptimidazole as synthesized according to 
Synthetic example 1 (c) with reference to the method disclosed in Bulletin 
of the Chemical Society of Japan, volume 33, No. 1, pages 56 to 58 (1960) 
was added to 50 ml of methanol, and 1 g of sodium methoxide was further 
added thereto. After reflux with heating for 10 hours, the solvent was 
distilled away, and 50 ml of benzene was added to the residue. The 
insoluble matters were filtered out, and the filtrate was concentrated. 
The resulting crystals were purified by silica gel column chromatography 
using ethyl acetate as a developing solvent. 
Colorless crystals 1 g (Yield 36.8%), Melting point 94.degree. C. 
(b) Synthesis of 2-methoxy-3-methylcycloheptimidazolium 
trifluoromethanesulfonate 
First, 0.9 g of 2-methoxycycloheptimidazole was added to 5 ml of anisole, 
and 1.1 g of methyl trifluoromethanesulfonate was added dropwise. After 
being stirred at room temperature for one hour, 30 ml of ethyl acetate was 
added, and deposited crystals were collected by filtration and dried. 
Colorless crystals 1.1 g (Yield 60.4%), Melting point 123.degree. to 
124.degree. C. 
(c) Synthesis of (4) 
2-Methoxy-3-methylcycloheptimidazolium trifluoromethanesulfonate (1 g) and 
1.08 g of 3-ethyl-2-methylbenzothiazolium p-toluenesulfonate were added to 
30 ml of acetonitrile, 0.86 ml of triethylamine was further added, and the 
mixture was refluxed with heating for 40 minutes. Solvent was distilled 
away, and the residue was subjected to purification by silica gel column 
chromatography using a mixed solvent of methanol/chloroform=1/4 as a 
developing solvent 
The resulting crystals were dissolved in 50 ml of methanol, the insoluble 
matters were filtered out in a hot state, and then a solution of 0.5 g of 
sodium iodide in 5 ml of methanol was added to the filtrate. Deposited 
crystals were collected by filtration, washed successively with methanol 
and water, and dried. 
Red crystals 0.2 g (Yield 13.9%), Melting point 190.degree. to 191.degree. 
C., .lambda.max=557 nm (.epsilon.=1.04.times.10.sup.5) (methanol). 
SYNTHETIC EXAMPLE 9: SYNTHESIS OF (3) 
Synthesis of (3) is stated below in order from synthesis of a raw material 
of the dye. 
(a) Synthesis of 2-hydroxycycloheptimidazole 
First, 60 g of 2-methylthiocycloheptimidazole as synthesized according to 
Synthetic example 1 (c) with reference to the method disclosed in Journal 
of the American Chemical Society, vol. 76, pages 3352 and 3353 (1954) was 
added to 300 ml of concentrated hydrochloric acid (hydrogen chloride 35%), 
and refluxed with heating for 2 hours and 30 minutes. Then, 500 ml of 
ethanol was added, and after stirring at room temperature, deposited 
crystals were collected by filtration. The crystals were dissolved in 0.5 
l of water, and pH was adjusted to around 7 with sodium bicarbonate. 
Deposited crystals were collected by filtration, washed with water and 
dried. 
Pale yellow crystals 40 g (Yield 80.3%), Melting point 245.degree. C. 
(b) Synthesis of 2-chlorocycloheptimidazole 
With reference to the method disclosed in Chemical and Pharmaceutical 
Bulletin, vol. 16, No. 7, pages 1300 to 1307 (1968), 10 g of 
2-hydroxycycloheptimidazole, 150 g of phosphorus oxychloride and 12 g of 
N,N-diethylaniline were stirred with heating to the inner temperature of 
70.degree. C. for 6 hours and 30 minutes. After the reaction, phosphorus 
oxychloride was distilled away under reduced pressure and 500 ml of ice 
water was added to the residue. Then, a sodium bicarbonate solution was 
added thereto to neutral pH, and extracted with chloroform (250 
ml.times.2). The chloroform layer was dried over anhydrous sodium sulfate, 
solvent was distilled away, and the residue was purified by silica gel 
column chromatography using ethyl acetate as a developing solvent. 
Colorless crystals 2.7 g (Yield 24%), Melting point 162.degree. to 
163.degree. C. 
(c) Synthesis of 2-chloro-3-methylcycloheptimidazolium 
trifluoromethanesulfonate 
2-Chlorocycloheptimidazole (0.78 g) was added to 4 ml of anisole, 0.93 g of 
methyl trifluoromethanesulfonate was added dropwise thereto, and the 
mixture was stirred at room temperature for 40 minutes. Then, 50 ml of 
ethyl acetate was added to the reaction solution, and deposited crystals 
were collected by filtration and dried. 
Colorless crystals 1.27 g (Yield 81.5%), Melting point 109.degree. to 
110.degree. C. 
(d) Synthesis of (3) 
First, 1,2 g of 2-chloro-3-methylcycloheptimidazolium 
trifluoromethanesulfonate and 1.28 g of 3-ethyl-2-methylbenzothiazolium 
p-toluenesulfonate were added to 30 ml of acetonitrile, 1 ml of 
triethylamine was further added, and the mixture was refluxed with heating 
for one hour and 30 minutes. After the reaction, solvent was distilled 
away therefrom, and the residue was purified by silica gel column 
chromatography using a mixed solvent of methanol/chloroform=1/4 as a 
developing solvent. The resulting crystals were dissolved in 100 ml of 
methanol, the insoluble matters were filtered out, and a solution of 0.6 g 
of sodium iodide in 5 ml of methanol was added to the filtrate. After 
being allowed to stand at room temperature for a while, deposited crystals 
were collected by filtration, washed with a small amount of methanol and 
dried. 
Red crystals 100 mg (Yield 5.7%), Melting point decomposed at 120.degree. 
C., .lambda.max=522 nm (4.32.times.10.sup.4) (methanol). 
SYNTHETIC EXAMPLE 10: SYNTHESIS OF (1) 
Synthesis of (1) is stated below in turn from synthesis of the starting 
substance of the dye. 
(a) Synthesis of cycloheptimidazole 
With reference to Journal of the American Chemical Society, vol. 76, pages 
3352 and 3353 (1954) 23 g of 2-mercaptocycloheptimidazole as synthesized 
in Synthetic example 1(b) was added to 210 ml of 10% nitric acid, and 
stirred with heating to the inner temperature of 80.degree. to 90.degree. 
C. for one hour. The reaction solution was neutralized with sodium 
bicarbonate and extracted with chloroform (250 ml.times.2). The chloroform 
layer was dried over anhydrous sodium sulfate and concentrated to 50 ml 
under reduced pressure, and then 200 ml of hexane was added. Deposited 
crystals were collected by filtration and dried. 
Pale yellow crystals 7 g (Yield 38.5%), Melting point 120.degree. C. 
(b) Synthesis of (1) 
First, 3.8 g of cycloheptimidazole was added to 20 ml of anisole, 7.2 g of 
methyl trifluoromethanesulfonate was added dropwise and the mixture was 
stirred at room temperature for 30 minutes. Precipitated oily matter was 
taken out by decantation. The whole oily matter and 5.1 g of 
3-ethyl-2-methylbenzothiazolium p-toluenesulfonate were added to 50 ml of 
acetonitrile, and 4 ml of triethylamine was further added. The mixture was 
refluxed with heating for one hour and solvent was distilled away. The 
resulting crude product was purified twice by silica gel column 
chromatography using a mixed solvent of methanol/chloroform=1/4 as a 
developing solvent. Then, 50 ml of methanol was added to the resulting 
crystals to dissolve it, and a solution of 1.5 g of sodium iodide in 5 ml 
of methanol was added. After being allowed to stand for a while, deposited 
crystals were collected by filtration, washed with methanol and dried. 
Red crystals 0.5 g (Yield 3.8%), Melting point 288.degree. to 290.degree. 
C., .lambda.max=550 nm (.epsilon.=5.98.times.10.sup.4) (methanol). 
SYNTHETIC EXAMPLE 11: SYNTHESIS OF (2) (A synthetic method different from 
Synthetic example 1) 
Synthesis of (2) is stated below in turn from synthesis of the starting 
substance of the dye. 
(a) Synthesis of 2-methoxy-5-methyl-2,4,6-cycloheptatrien-1-one 
2-Hydroxy-5-methyl-2,4,6-cycloheptatrien-1-one (223 g) as obtained by the 
method disclosed in Bulletin of the Chemical Society of Japan, vol. 32, 
pages 493 to 496 (1959) and 340 g of potassium carbonate were added to 1.3 
l of acetone containing 10% water, 310 g of dimethyl sulfate was added 
thereto, and the mixture was refluxed with heating for 7 hours. After 
being allowed to stand overnight, deposited inorganic matters were 
filtered out and acetone in the filtrate was distilled away under reduced 
pressure. Then, 1 l of water was added to the resulting concentrate, and 
extracted with chloroform (0.25 l.times.4). 
The chloroform layer was dried over anhydrous sodium sulfate, evaporated to 
distill away the solvent and distilled under reduced pressure (130.degree. 
C./0.5 mmHg). 
Colorless liquid 224 g (Yield 91%). 
(b) Synthesis of 2-mercapto-6-methylcycloheptimidazole 
2-Methoxy-5-methyl-2,4,6-cycloheptatrien-1-one (165 g) and 84 g of thiourea 
were added to 255 g of a 28% sodium methoxide methanol solution, and 
stirred at room temperature for 30 minutes. Then, 600 ml of methanol was 
added and acetic acid was added until the pH of the solution becomes 
around 5. Deposited crystals were collected by filtration, throughly 
washed with methanol and dried. 
Yellow crystals 145.4 g (Yield 75%), Melting point 300.degree. C. or more. 
(c) Synthesis of 6-methyl-2-methylthiocycloheptimidazole 
First, 38 g of potassium hydroxide was dissolved in 800 ml of methanol, 
108.5 g of 2-mercapto-6-methylcycloheptimidazole was added, and the 
mixture was stirred with heating to the inner temperature of about 
45.degree. C. Then, 131.2 g of dimethyl sulfate was added dropwise thereto 
and stirred with heating to the inner temperature of about 45.degree. C. 
for one hour. After the solvent was distilled away in some extent under 
reduced pressure, 1 l of water was added and extracted with chloroform 
(0.5 l.times.2). The chloroform layer was dried over anhydrous sodium 
sulfate and evaporated to 200 ml under reduced pressure to distil away the 
solvent. With the addition of 1 l of hexane, crystals were deposited, and 
they were collected by filtration and dried. 
Colorless crystals 99.6 g (Yield 85.0%), Melting point 110.degree. to 
111.degree. C. 
(d) Synthesis of 
3,6-dimethyl-2-methylthiocycloheptimidazoliumtrifluoromethanesulfonate 
6-Methyl-2-methylthiocycloheptimidazole (27 g) was added to 100 ml of 
anisole and stirred under ice cooling. Then, 28 g of methyl 
trifluoromethanesulfonate was added dropwise thereto, and stirred under 
ice cooling. The mixture was further stirred at room temperature for one 
hour, 200 ml of ethyl acetate was added, and deposited crystals were 
collected by filtration and dried. 
Colorless crystals 40.3 g (Yield 80%), Melting point 175.degree. to 
177.degree. C. 
(e) Synthesis of (2) 
3,6-Dimethyl-2-methylthiocycloheptimidazolium trifluoromethanesulfonate (3 
g) and 3.4 g of 3-ethyl-2-ethylthiobenzothiazolium p-toluenesulfonate were 
added to 50 ml of acetonitrile, 2.4 ml of triethylamine was added thereto, 
and the mixture was stirred with heating to the inner temperature of 
45.degree. C. for one hour. After the reaction, 200 ml of ethyl acetate 
was added and deposited crystals were collected by filtration. The 
crystals were added to 100 ml of methanol and heated to dissolve it, and 
the insoluble matters were filtered out in a hot state. A solution of 1.5 
g of sodium iodide in 10 ml of methanol was added to the filtrate, and 
allowed to stand. Deposited crystals were collected by filtration, 
successively washed with methanol and water, and dried. 
Purple crystals 1.5 g (Yield 35.9%), Melting point 260.degree. to 
264.degree. C. 
SYNTHETIC EXAMPLE 12: SYNTHESIS OF (7) (A synthetic method different from 
Synthetic example 2) 
3,6-Dimethyl-2-methylthiocycloheptimidazolium trifluoromethanesulfonate 
(3g) as synthesized in Synthetic example 1 (d) and 3.3 g of 
3-ethyl-2-ethylthiobenzoxazolium p-toluenesulfonate were added to 50 ml of 
acetonitrile, 2.4 ml of triethylamine was added thereto, and the mixture 
was stirred with heating to the inner temperature of 40.degree. C. for one 
hour. After the reaction, 200 ml of ethyl acetate was added and deposited 
crystals were collected by filtration. The crystals were added to 150 ml 
of methanol and dissolved therein with heating, and the insoluble matters 
were filtered out in a hot state. A solution of 1.5 g of sodium iodide in 
10 ml of methanol was added to the filtrate and allowed to cool. Deposited 
crystals were collected by filtration, successively washed with methanol 
and water, and dried. 
Purple crystals 2.4 g (Yield 59%), Melting point 300.degree. C. or more. 
SYNTHETIC EXAMPLE 13: SYNTHESIS OF (10) 
3,6-Dimethyl-2-methylthiocycloheptimidazolium trifluoromethanesulfonate (3 
g) as synthesized in Synthetic example 11 (d) and 5 g of 
2-(2-acetanilidovinyl)-3-ethylbenzothiazolium p-toluenesulfonate were 
added to 50 ml of methanol, 2.4 ml of triethylamine was further added, and 
the mixture was stirred at room temperature for 2 hours. A solution of 1 g 
of sodium iodide in 10 ml of methanol was added thereto, and stirred for a 
while to deposit crystals. 
The crystals were collected by filtration, added to 200 ml of methanol and 
dissolved therein under reflux with heating. The resulting insoluble 
matters were filtered out in a hot state, and the filtrate was allowed to 
cool. Deposited crystals were collected by filtration, washed with 
methanol and dried. 
Purple crystals 2.5 g (Yield 56.8%), Melting point 215.degree. to 
216.degree. C., .lambda.max=672 nm (.epsilon.=1.02.times.10.sup.5) 
(methanol). 
SYNTHETIC EXAMPLE 14: SYNTHESIS OF (60) 
3,6-Dimethyl-2-methylthiocycloheptimidazolium trifluoromethanesulfonate (3 
g) as synthesized in Synthetic example 11 (d) and 3.1 g of 
5-(acetanilidomethylidene)-3-ethylrhodanine were added to 100 ml of 
methanol, 2.4 ml of triethylamine was further added, and the mixture was 
stirred at room temperature for one hour. 
Deposited crystals were collected by filtration, 200 ml of methanol was 
added to them, and the mixture was refluxed with heating to dissolve them. 
The insoluble matters were filtered out and the filtrate was allowed to 
cool. Deposited crystals were collected by filtration, washed with 
methanol and dried. 
Purple crystals 2.1 g (Yield 66.0%), Melting point 151.degree. to 
152.degree. C., .lambda.max=621 nm (.epsilon.=5.20.times.10.sup.4) 
(methanol). 
SYNTHETIC EXAMPLE 15: SYNTHESIS OF (10) (A synthetic method different from 
Synthetic example 13) 
Synthesis of (10) is stated below in turn from synthesis of the starting 
substance of the dye. 
(a) Synthesis of 
6-(2-acetanilidovinyl)-3-methyl-2-methylthiocycloheptimidazolium 
trifluoromethanesulfonate 
3,6-Dimethyl-2-methylthiocycloheptimidazolium trifluoromethanesulfonate (10 
g) as synthesized in Synthetic example 11 (d) and 8.3 g of 
N,N'-diphenylformamidine were added to 150 ml of acetic anhydride, and 
stirred with heating to the inner temperature of about 90.degree. C. for 
one hour. After being allowed to cool, 150 ml of ethyl acetate was added 
thereto, and deposited crystals were collected by filtration and dried. 
Yellow crystals 12 g (Yield 85.1%), Melting point 162.degree. to 
163.degree. C. 
(b) Synthesis of (10) 
6-(2-acetanilidovinyl)-3-methyl-2-methylthiocycloheptimidazolium 
trifluoromethanesulfonate (4 g) and 2.5 g of 
3-ethyl-2-methylbenzothiazolium p-toluenesulfonate were added to 50 ml of 
methanol, 2.2 ml of triethylamine was added and the mixture was stirred at 
room temperature for one hour. Post-treatment was conducted in the same 
manner as in Synthetic example 13. 
Purple crystals 2.7 g (Yield 73.0%), Melting point 215.degree. to 
216.degree. C. 
SYNTHETIC EXAMPLE 16: SYNTHESIS OF (60) (A synthetic method different from 
Synthetic example 14) 
6-(2-Acetanilidovinyl)-3-methylthiocycloheptimidazolium 
trifluoromethanesulfonate (4 g) as synthesized in Synthetic example 15 (a) 
and 1.16 g of 3-ethylrhodanine were added to 100 ml of methanol, 2.2 ml of 
triethylamine was further added, and the mixture was stirred at room 
temperature for one hour. Thereafter, treatments similar to those in 
Synthetic example 14 were conducted. 
Purple crystals 2.3 g (Yield 85.2%), Melting point 151.degree. to 
152.degree. C. 
SYNTHETIC EXAMPLE 17: SYNTHESIS OF (45) 
3,6-Dimethyl-2-methylthiocycloheptimidazolium trifluoromethanesulfonate (5 
g), 1.66 g of N,N'-diphenylformamidine and 2 ml of acetic anhydride were 
added to 100 ml of methanol, 3.9 ml of triethylamine was further added, 
and the mixture was stirred at room temperature for one hour. A solution 
of 1 g of sodium iodide in 10 ml of methanol was added to the reaction 
solution. After stirring for a while, deposited crystals were collected by 
filtration and dissolved in 100 ml of methanol through reflux with 
heating, and the insoluble matters were filtered out in a hot state. 
The filtrate was allowed to cool, and deposited crystals were collected by 
filtration, washed with methanol and dried. 
Purple crystals 2.1 g (Yield 54.5%), Melting point 140.degree. to 
141.degree. C., .lambda.max=825 nm (.epsilon.=1.21.times.10.sup.5) 
(methanol). 
(Structure determination) 
All the dyes of the present invention as synthesized in Synthetic examples 
1 to 17 exhibit molecular ion (parent) peak in mass spectra. Further, 
coincides of elementary analyses were observed. 
The following are .sup.1 H-Nmr data of some dyes. All the measurements were 
conducted using 400 MHz.sup.1 H-Nmr and DMSO-d.sup.6 solvent. 
(1): Measuring temperature 373K 
##STR92## 
.delta. ppm, JinHz: 
1.45 (3 H, t, J=8, N--CH.sub.2 --CH.sub.3) 
3.93 (3 H, s, N--CH.sub.3) 
4.67 (2 H, q, J=8, N--CH.sub.2 CH.sub.3) 
6.90 (1 H, S, H-9) 
7.55-7.66 (4 H, m, H-13 (or 14), 3 H among H-4, 5, 7, 8) 
7.73 (1 H, td, J=8, 0.5, H-14 (or 13)) 
7.83 (1 H, dd, J=12, 1 H among H-4, 5, 7, 8) 
7.95 (1 H, d, J=8, H-15), 
8.17 (1 H, d, J=8, H-12), 
8.33 (1 H, s, H-2). 
(2): Measuring temperature 333K 
##STR93## 
.delta. ppm, JinHz: 
1.41 (3 H, t, J=8, N--CH.sub.2 CH.sub.3) 
2.79 (3 H, s, S--CH.sub.3) 
3.78 (3 H, s, N--CH.sub.3) 
4.62 (2 H, q, J=8, N--CH.sub.2 CH.sub.3) 
6.88 (1 H, S, H-9) 
7.54 (1 H, t, J=8, H-14 (or 13)) 
7.67 (2 H, d, J=12, H-5, 7 (or 4,8)) 
7.69 (1 H, t, J=8, H-13 (or 14)) 
7.88 (2 H, d, J=12, H-4, 8 (or 5,7)) 
7.90 (1 H, d, J=8, H-15) 
8.14 (1 H, d, J=8, H-12). 
(7): Measuring temperature 373K 
##STR94## 
.delta.ppm, JinHz: 
1.44 (3 H, t, J=7, N--CH.sub.2 CH.sub.3) 
2.79 (3 H, s, S--CH.sub.3) 
3.79 (3 H, s, N--CH.sub.3) 
4.38 (2 H, q, J=7, N--CH.sub.2 CH.sub.3) 
6.22 (1 H, S, H-9) 
7.48 (1 H, td, J=8, 1, H-14 (or 13)) 
7.54 (1 H, td, J=8, 1, H-13 (or 14)) 
7.73 (1 H, dd, J=8, 1, H-15) 
7.79 (1 H, dd, J=8, 1, H-12) 
7.85-7.89 (2 H, m, H-5, 7 (or 4, 8)) 
7.91-8.02 (2 H, bm, H-4, 8 (or 5, 7)). 
(49): Measuring temperature 373K 
##STR95## 
.delta.ppm, JinHz: 
2.84 (6 H, s, --SCH.sub.3) 
3.82 (6 H, s, N--CH.sub.3) 
7.36 (2 H, t, J=12, H-7) 
7.47 (2 H, t, J=12, H-6) 
7.84 (2 H, d, J=12, H-5) 
8.22 (2 H, d, J=12, H-8) 
8.44 (1 H, S, H-9). 
Further, Nucleus Overhauser Effect (NOE) was observed between N--CH.sub.3 
and H-8. 
(50): Measuring temperature 373K 
##STR96## 
.delta.ppm, JinHz: 
2.88 (6 H, s, --SCH.sub.3) 
3.77 (6 H, s, N--CH.sub.3) 
7.19 (2 H, t, J=12, H-7) 
7.27 (2 H, t, J=12, H-6) 
7.33 (2 H, d, J=13, H-9) 
7.66 (2 H, d, J=12, H-5) 
8.18 (2 H, d, J=12, H-8) 
9.10 (1 H, bt, J=13, H-10). 
(58): Measuring temperature 323K 
##STR97## 
.delta.ppm, JinHz: 
1.20 (6 H, t, J=8, N--CH.sub.2 CH.sub.3) 
2.86 (3 H, s, --SCH.sub.3) 
3.88 (3 H, s, N--CH.sub.3) 
4.48 (4 H, q, J=8, N--CH.sub.2 CH.sub.3) 
8.43 (1 H, d, J=12, H-5 or 7 (or 4 or 8)) 
8.46 (1 H, d, J=12, H-5 or 7 (or 4 or 8)) 
9.17 (1 H, d, J=12, H-4 or 8 (or 5 or 7)) 
9.20 (1 H, d, J=12, H-4 or 8 (or 5 or 7)). 
(59): Measuring temperature 323K 
##STR98## 
.delta.ppm, JinHz: 
0.89 (6 H, t, J=8, --N(CH.sub.2).sub.3 CH.sub.3) 
1.28 (4 H, qt, J=8, NCH.sub.2 CH.sub.2 CH.sub.3) 
1.52 (4 H, tt, J=8, NCH.sub.2 CH.sub.2 CH.sub.2 CH.sub.3) 
2.82 (3 H, s, --SCH.sub.3) 
3.83 (3 H, s, --NCH.sub.3) 
3.83 (4 H, t, J=8, NCH.sub.2 CH.sub.2 CH.sub.2 CH.sub.3) 
8.23 (1 H, d, J=12, H-5 or 7 (or 4 or 8)) 
8.25 (1 H, d, J=12, H-5 or 7 (or 4 or 8)) 
9.18 (1 H, d, J=12, H-4 or 8 (or 5 or 7)) 
9.22 (1 H, d, J=12, H-4 or 8 (or 5 or 7)). 
(77): Measuring temperature 298K 
##STR99## 
.delta.ppm, JinHz: 
1.23 (3 H, t, J=8, N--CH.sub.2 --CH.sub.3) 
1.26 (3 H, t, J=8, N--CH.sub.2 --CH.sub.3) 
2.77 (3 H, s, S--CH.sub.3) 
3.60 (2 H, q, J=8, N--CH.sub.2 CH.sub.3) 
3.65 (2 H, q, N--CH.sub.2 CH.sub.3) 
3.73 (3 H, s, N--CH.sub.3) 
6.07 (1 H, d, J=13, H-10) 
7.36 (1 H, t, J=12, H-7) 
7.67 (1 H, d, J=12, H-5) 
7.75 (1 H, t, J=12, H-6) 
7.91 (1 H, d, J=12, H-8) 
8.50 (1 H, t, J=13, H-9). 
Methine dyes used in optical recording media of the present invention may 
be used alone or in combination of 2 or more, or may be used together with 
dyes other than methine dyes of the present invention. Further, it is also 
effective to use various antioxidants or singlet oxygen quenchers toghther 
therewith for enhancement of reading durability. Further, various resins 
may also be used together. 
It is also possible to increase reading durability by forming chelate 
compounds with methine dyes of the invention by addition of transition 
metal ions. This method is remarkably effective when methine dyes of the 
invention have nitrogen-containing heterocycles. 
Various quenchers may be used in the invention, but preferred ones are 
transition metal complexes which lower deterioration by reproduction and 
have good compatibility with dyes. Preferred center metals are Ni, Co, Cu, 
Pd, Pt and the like. 
Examples of novel quenchers which may be used in the invention include 
quenchers represented by the formulae (XXI) and (XXII): 
##STR100## 
wherein [Cat.sub.1 ] and [Cat.sub.2 ] each represent a cation necessary 
for making each compound neutral, M.sub.1 and M.sub.2 each represent 
nickel, copper, cobalt, palladium or platinum, and n represents 1 to 2. 
Examples of an inorganic cation in the cation represented by [Cat.sub.1 ] 
or [Cat.sub.2 ] in the aforesaid general formula (XXI) or (XXII) include 
alkali metal ions such as Li.sup.+, Na.sup.+ and K.sup.+, alkaline earth 
metal ions such as Mg.sup.2 +, Ca.sup.2 + and Ba.sup.2+. 
Further, examples of an organic cation therein include quaternary ammonium 
ions and quaternary phosphonium ions. 
Preferred cations among the above cations [Cat.sub.1 ] and [Cat.sub.2 ] are 
those represented by the following general formula (XXIII-a), (XXIII-b), 
(XXIII-c), (XXIII-d) or (XXIII-e): 
##STR101## 
wherein R.sup.11, R.sup.12, R.sup.13, R.sup.14, R.sup.15, R.sup.16, 
R.sup.17, R.sup.18, R.sup.19, R.sup.20, R.sup.21 and R.sup.22 each 
represent a substituted or unsubstituted alkyl group having 1 to 20 carbon 
atoms, or a substituted or unsubstituted aryl group having 6 to 14 carbon 
atoms, and Z.sup.1 and Z.sup.2 each represent a nonmetal atomic group 
which forms a 5-membered or 6-membered ring together with a nitrogen atom 
or a phosphorus atom in each formula. 
The above substituted or unsubstituted alkyl group having 1 to 20 carbon 
atoms includes, for example a methyl group, an ethyl group, a n-butyl 
group, an iso-amyl group, a n-dodecyl group and n-octadecyl group. The 
aryl group having 6 to 14 carbon atoms include, for example a phenyl 
group, a tolyl group and an .alpha.-naphtyl group. 
These alkyl groups and aryl groups may respectively be substituted with a 
cyano group, a hydroxyl group, an alkyl group having 1 to 20 carbon atoms 
(e.g., a methyl group, an ethyl group, an n-butyl group or an n-octyl 
group), an aryl group having 6 to 14 carbon atoms (e.g., a phenyl group, a 
tolyl group or an .alpha.-naphthyl group), an acyloxy group having 2 to 20 
carbon atoms (e.g., an acetoxy group, a benzoyl group or 
p-methoxybenzoyloxy group), an alkoxy group having 1 to 6 carbon atoms 
(e.g., a methoxy group, an ethoxy group, a propoxy group or a butoxy 
group), an aryloxy group (e.g., a phenoxy group or a tolyloxy group), an 
aralkyl group (e.g., a benzyl group, a phenethyl group or an anisyl 
group), an alkoxycarbonyl group (e.g., a methoxycarbonyl group, an 
ethoxycarbonyl group or an n-butoxycarbonyl group), an aryloxycarbonyl 
group (e.g., a phenoxycarbonyl group or a tolyloxycarbonyl group), an acyl 
group (e.g., an acetyl group or a benzoyl group), an acylamino group 
(e.g., an acetylamino group or a benzoylamino group), a substituted or 
unsubstituted carbamoyl group (e.g., an N-ethylcarbamoyl group or an 
N-phenylcarbamoyl group), an alkylsulfonylamino group (e.g., a 
methylsulfonylamino group), an arylsulfonylamino group (e.g., a 
phenylsulfonylamino group), a substituted or unsubstituted sulfamoyl group 
(e.g., an N-ethylsulfamoyl group or an N-phenylsulfamoyl group), an alkyl- 
or arylsulfonyl group (e.g., a mesyl group or a tosyl group) or the like. 
Z.sup.1 and Z.sup.2 each represent a nonmetal atomic group necessary for 
forming a 5-membered ring or a 6-membered ring as aforesaid. The 
5-membered ring or 6-membered ring may include a pyridine ring, an 
imidazole ring, a pyrrole ring, a 2-pyrroline ring, a pyrrolidine ring, a 
piperidine ring, a pyrazole ring, a pyrazoline ring, an imidazoline ring 
and the like. 
Cations represented by the general formula (XXIII-b) may include, for 
example, a dodecylpyridinium group, a hexadecylpyridinium group and a 
dodecylimidazolium group. Cations represented by the general formula 
(XXIII-c) may include, for example, an N-ethyl-N-hexadecylpiperidinium 
group, an N-ethyl-N-dodecylpyrazolidinium group. 
Cations preferably used in the present invention among cations represented 
by the above general formulae (XXIII-a), (XXIII-b), (XXIII-c), (XXIII-d) 
and (XIII-e) are (XXIII-a), (XXIII-b), (XXIII-d) and (XXIII-e) in view of 
availability of the raw materials and preparation cost. 
The kind of these cations [Cat.sub.1 ] and [Cat.sub.2 ] has an influence on 
the solubilities of the compounds represented by the aforesaid general 
formula (XXI) or (XXII) in organic solvents. 
In general, when substituents linking to the quaternary hereto atom are 
alkyl groups, solubility of the compound increases as the chain lengths of 
the alkyl groups become longer. This tendency is remarkable in case of 
tetraalkyl substituted ammonium or tetraalkyl substituted phosphonium, and 
cations having a total carbon number of 17 or more in case of ammonium 
cations and cations having a total carbon number of 4 or more in case of 
phosphonium cations each bestow high solubilities on the compounds. 
Enumeration of M.sub.1 or M.sub.2 in the compounds represented by the 
aforesaid general formula (XXI) or (XXII) in order of preference is 
nickel, cobalt, copper, palladium and platinum. 
The metal complexes of the general formula (XXI) or (XXII) have 
stereostructures of plane four coordination. Though it cannot be 
definitely determined whether the thioketone groups in the compounds of 
the general formula (XXII) exist symmetrically or unsymmetrically in 
relation to the center metal, the thioketone groups are represented for 
convenience's sake as in the general formula (XXII) in the present 
specification. 
The compounds represented by the aforesaid general formula (XXI) or (XXII) 
may be synthesized as follows. 
A compound of the general formula (XXI) (n=2): Disodium 
1,3-dithiol-2-thione-4,5-dithiolate obtained by reacting carbon disulfide 
with sodium is converted to a zinc complex, and benzoyl chloride is 
reacted with the complex to form a bisbenzoylthio compound. After 
decomposition with an alkali, the bisbenzoylthio compound is reacted with 
a metal salt to obtain the captioned compound. 
Further, a compound of the general formula (XXI) (n=1) may be obtained by 
oxidizing a complex obtained as above-described (n=2) with a proper 
oxidizing agent. 
A compound of the general formula (XXII) (n=2): First, disodium 
1,3-dithiol-2-thione-4,5-dithiolate obtained by reaction of carbon 
disulfide with sodium is heated to above 130.degree. C. to isomerize it to 
disodium 1,2-dithiol-3-thione-4,5-dithiolate. Then, this dithiolate is 
converted to a zinc complex, and benzoyl chloride is reacted with the zinc 
complex to form a bisbenzoylthio compound, which is the decomposed with an 
alkali and reacted with a metal salt to obtain the captioned compound. 
A compound of the general formula (XXII) (n=1) may be obtained by oxidizing 
a complex obtained as above-described (n=2) with a proper oxidizing agent. 
Further, the 1,3-dithiol-2-thione-4,5-dithiolate anion which is an 
intermediate for obtaining a compound of the general formula (XXI) or 
(XXII) may also be obtained by electrochemical reduction besides the 
Na-reduction method described above. 
Preferred compounds among those represented by the aforesaid general 
formulae (XXI) are illustrated as follows. 
##STR102## 
Synthetic examples of compounds represented by the general formula (XXI) is 
described as follows. 
SYNTHETIC EXAMPLE 8: 
Synthesis of exemplified compound (XXI-4) 
(1-1) Synthesis of 
bis(tetraethylammonium)bis(1,3-dithiol-2-thione-4,5-dithiolato)zinc 
complex 
All reaction procedures were conducted under an argon atmosphere. 23 g of 
sodium was cut into small pieces and dispersed in 180 ml of carbon 
disulfide, followed by dropwise addition in a slow speed of 200 ml of 
dimethylformamide thereto with stirring. During the dropwise addition, 
caution should be given so that the mixture does not rapidly generate 
heat. After the dropwise addition of dimethylformaminde, the mixture was 
gently heated with caution and refluxed for 24 hours. After completion of 
the reaction the unreacted sodium was removed by filtration. Then, 50 ml 
of ethanol was added to the filtrate, and the mixture was stirred at room 
temperature for 2 hours. Carbon disulfide was distilled away from this 
solution at room temperature under reduced pressure. Then, 300 ml of water 
was slowly added dropwise thereto and the resulting solution was filtered. 
Separately in advance, 20 g of zinc chloride was dissolved in 500 ml of 
methanol and 500 ml of concentrated ammonia water was added thereto to 
prepare a solution. This solution was added to the above filtrate at room 
temperature. After stirring for 5 minutes, an aqueous solution of 53 g of 
tetraethylammonium bromide in 250 ml of water was added to the mixture to 
immediately form a red precipitate, which was recovered by filtration and 
air-dried to obtain the captioned zinc complex. 
(1-2) Synthesis of 4,5-bis(benzoylthio)-1,3-dithiol-2-thione 
22 g of the zinc complex obtained in (1-1) was dissolved in 500 ml of 
acetone and filtered. 150 ml of benzoyl chloride was added to the filtrate 
with stirring to form immediately a yellow precipitate. The precipitate 
was recovered by filtration, washed with water and air-dried to obtain 16 
g of the captioned compound. 
(1-3) Synthesis of exemplified compound (XXI-4) 
9.2 g of the bis(benzoylthio) compound obtained in (1-2) was dissolved in 
50 ml of methanol. Then, 6.3 g of a 28% methanol solution of sodium 
methoxide was added thereto, followed by stirring for 10 minutes. To this 
solution was added a solution of 2.4 g of nickel chloride hexahydrate in 
50 ml of methanol, and the mixture was stirred at room temperature for 30 
minutes. To the resulting solution was added a solution of 8.5 g of 
tetrabutylphosphonium bormide in 100 ml of methanol to form immediately a 
black precipitate. The mixture was stirred for additional 20 minutes and 
filtered. The solid was washed with acetone, air-dried and recrylstallized 
from acetone-isopropyl alcohol to obtain the captioned compound. Yield 3.8 
g. 
SYNTHETIC EXAMPLE 9: 
Synthesis of exemplified compound (XXI-2) 
1 g of the nickel complex obtained in (1-3) was dissolved in 60 ml of 
acetone, and 30 ml of acetic acid was added thereto. The mixture was 
stirred for 3 hours and the solvent was distilled away to form black 
crystals, which was then recrystallized from acetone-methanol to obtain 
the desired exemplified compound (XXI-2). Yield 0.4 g, M.P. 185.degree. 
C., .lambda.max.: 1125 nm, .epsilon.max.: 2.51.times.10.sup.4 (in CH.sub.2 
Cl.sub.2) 
Examples of known quenchers which may be used in the invention include the 
following compounds disclosed in J.P. KOKAI No. 59-178295. 
(i) Bisdithio-.alpha.-diketone series 
##STR103## 
wherein R.sup.1 to R.sup.4 each represent an alkyl group or an aryl 
group, and M represents a divalent transition metal atom. 
(ii) Bisphenyldithiol series 
##STR104## 
wherein R.sup.5 and R.sup.6 each represent an alkyl group or a halogen 
atom, and M represents a divalent transition metal atom. 
(iii) Acetylacetonate cholate series 
(iv) Dithiocarbamic acid chelate series 
(v) Bisphenylthiol series 
(vi) Thiocatechol chelate series 
(vii) Salicylaldehyde oxime series 
(viii) Thiobisphenolate chelate series 
(ix) Phosphonous acid chelate series 
(x) Benzoate series 
(xi) Hindered amine series 
(xii) Transition metal salts 
Besides the above compounds, aminium series or diimonium series compounds 
represented by the following formula may also be used in the invention as 
known quenchers: 
##STR105## 
wherein R represents an alkyl group or an aryl group. Specific examples 
thereof include IRG-002, IRG-003, IRG-022 and IRG-033 each manufactured by 
NIPPON KAYAKU CO., LTD. 
A linkage compound of a cation of methine dye(s) of the present invention 
to an anion of a quencher may also be used in the invention. 
A quencher is generally used in an amount of 0.05 to 12 moles, preferably 
0.1 to 1.2 moles per 1 mole of methine dye(s) of the invention. 
Though a quencher is preferably contained in the dye film recording layer, 
it may be contained in a layer different from the recording layer. It is 
possible to provide a subbing layer on the support, a protective layer on 
the recording layer, and/or a reflective layer on the support or on the 
recording layer in the optical recording medium of the invention. 
Known supports may arbitrary be used as a support. Typical examples thereof 
are glass and plastics such as acryls, polycarbonates, polysulfones, 
polyimides, amorphous polyolefins, epoxy resins, polyesters and the like. 
The support may be used in various shapes such as disc-like, card-like, 
sheet-like and roll film-like shapes. 
A groove may be formed on the glass or plastic support in order to make 
tracking easy during recording. Further, a subbing layer of a plastic 
binder, or an inorganic oxide, an inorganic sulfide or the like may be 
provided on the glass or plastic support. A subbing layer having a thermal 
conductivity lower than the support is preferable. Further, it is also 
possible to make two recording madia facing with each other so that both 
recording layers are inside, namely to make two recording media so-called 
air sandwich structure. 
The recording layer in the present invention may be formed, for example, by 
dissolving a dye of the invention and a quencher in an organic solvent 
(for example, methanol, ethanol, isopropyl alcohol, a fluorinated alcohol 
such as 2,2,3,3-tetrafluoropropanol, dichloromethane, dichloroethane or 
acetone), and, if necessary, adding a proper binder (for example, PVA, 
PVP, polyvinyl butyral, polycarbonate, nitrocellulose, polyvinyl formal, 
methyl vinyl ether, chlorinated paraffin, maleic anhydride copolymer, 
styrenebutadiene copolymer or xylene series resin), and applying the 
solution (for example by spin coating) onto a support. The recording layer 
may also be formed by co-depositing a methine dye of the invention and a 
quencher on a support, or by vacuum-depositing a methine dye of the 
invention and then applying a quencher. When a binder is used, it is 
preferable to use it in an amount of 0.01 to 2 times the weight of the 
dye. Further, it is also possible to form a thin film according to 
Langmuir-Blodgett's technique using a dye. 
It is possible to provide one or more of the recording layers in the 
present invention. 
An antioxidant or a fading inhibitor may be contained in the recording 
layer or a layer adjacent thereto in order to inhibit deterioration of the 
dye. 
Film thickness of the recording layer is usually in the range of 0.01 to 2 
.mu.m, preferably in the range of 0.02 to 0.8 .mu.m. In case of reflection 
reading, it is particularly preferable that the thickness is odd number 
times the 1/4 of the laser wave length used for reading. 
When a layer for reflecting semiconductor laser, He-Ne laser or the like is 
provided, the optical recording medium of the present invention may be 
made either by providing a reflecting layer on a support and then 
providing a recording layer on the reflecting layer in such a manner as 
aforementioned, or by providing a recording layer on a support and then 
providing a reflecting layer thereon. 
The reflecting layer may be provided in such a manner as described below 
besides a sputtering method, an ion plating method or the like. 
For example, a solution which is prepared by dissolving a metal salt or a 
metal complex salt in a water soluble resin (PVP, PVA or the like) and 
further adding a reducing agent thereto is applied onto a support and the 
resulting support is dried with heating at 50.degree. to 150.degree. C., 
preferably 60.degree. to 100.degree. C., whereby a reflecting layer is 
provided thereon. 
The metal salt or the metal complex salt is used in a weight ratio of 0.1 
to 10, preferably 0.5 to 1.5 based on the resin. Further, as for the 
thickness of the recording layer, it is proper that the thickness of the 
metal particle reflecting layer is in the range of 0.01 to 0.1 .mu.m and 
that of the light absorption layer is in the range of 0.01 to 1 .mu.m. 
Usable metal salts and metal complex salts include silver nitrate, 
potassium silver cyanide, potassium gold cyanide, silver ammine complex, 
silver cyan complex, gold salt or gold cyan complex and the like. Usable 
reducing agents include formalin, tartaric acid, a tartrate, a 
hypophosphite, sodium borohydride, dimethylamine borane and the like. The 
reducing agent may be used in the range of 0.2 to 10 moles, preferably 0.5 
to 4 moles per 1 mole of the metal salt or the metal complex salt. 
In the optical recording medium of the present invention, recording of 
information is conducted by applying a spot-like high energy beam such as 
laser (for example, semiconductor laser and He-Ne laser) onto the 
recording layer through the support or from the opposite side of the 
support. That is to say, light absorbed in the recording layer is 
converted to heat and pits are formed in the recording layer. 
On the other hand, reading of information is conducted by applying a laser 
beam with a low power of the threshold value energy or less for recording, 
detecting the difference in quantity of reflected light or quantity of 
transmitted light between pitted areas and unpitted areas. 
The present invention is further explained in detail below according to the 
examples. 
EXAMPLE 1 
A dye and a quencher, and a binder when needed, each shown in Table 2 were 
dissolved in a mixed solvent of methanol, methyl ethyl ketene and 
dichloroethane in a proper ratio. A surface-hardened polycarbonate support 
with a groove (1.6 .mu. pitch, 750.ANG. depth) was coated with the 
solution to a thickness of 0.1 .mu.m, and dried. The weight ratio of the 
dye and the quencher was 3:1, and in case of using a binder, the weight 
thereof was 1/5 of the dye. 
Evaluation conditions were as follow. 
______________________________________ 
(Recording and reproduction) 
Laser Semiconductor laser (GaAlAs) 
Wavelength of laser 
780 nm 
Beam diameter of laser 
1.6 .mu.m 
Line speed 5 m/s 
Recording power 
8 mW 
Recording frequency 
2.5 MHz 
Recording duty 50% 
Reproduction power 
0.4 mW 
(Evaluation of deterioration by reproduction) 
Reproduction power 
1.0 mW 
Reproduction number 
10.sup.5 times 
(Evaluation of deterioration during preservation) 
Preservation 60.degree. C., 90% RH 
temperature 
and humidity 
Preservation time 
for 30 days 
______________________________________ 
TABLE 2 
__________________________________________________________________________ 
C/N (dB) 
Just after 
Deterioration 
Deterioration 
Sample No. 
Dye 
Quencher 
Binder preparation 
by reproduction 
during preservation 
Note 
__________________________________________________________________________ 
1 A -- -- 54 45 42 Comparative example 
2 A XXI-2 -- 52 45 48 Comparative example 
3 A -- Polystyrene 
50 46 42 Comparative example 
4 A XXI-4 Chlorinated paraffin 
52 46 48 Comparative example 
5 B -- -- 53 44 40 Comparative example 
6 B XXI-2 -- 50 43 47 Comparative example 
7 B -- Polystyrene 
50 44 43 Comparative example 
8 B XXI-2 Chlorinated paraffin 
51 44 48 Comparative example 
9 16 -- -- 55 50 49 Present invention 
10 " XXI-2 -- 52 48 53 Present invention 
11 " -- Polystyrene 
51 48 48 Present invention 
12 " XXI-4 Nitrocellulose 
52 49 50 Present invention 
13 21 -- -- 55 51 50 Present invention 
14 " XXI-2 -- 53 50 52 Present invention 
15 21 -- Polystyrene 
52 49 49 Present invention 
16 " XXI-4 Polystyrene 
52 49 51 Present invention 
17 30 -- -- 54 50 49 Present invention 
18 " XXI-2 -- 53 49 52 Present invention 
19 " -- Polyethylene acrylate 
52 49 48 Present invention 
20 " XXI-4 Polyvinyl butyral 
52 49 51 Present invention 
21 47 -- -- 55 51 51 Present invention 
22 " XXI-2 -- 54 50 54 Present invention 
23 " -- Polystyrene 
54 51 50 Present invention 
24 " XXI-4 Polyvinyl formal 
53 52 51 Present invention 
25 50 -- -- 54 50 51 Present invention 
26 " Nickel acetate 
-- 53 49 52 Present invention 
27 50 -- Polyvinyl alcohol 
53 49 50 Present invention 
-28 50 Copper 
acetate Polycarbonate 
53 49 52 Present 
invention 
29 52 -- -- 54 50 50 Present invention 
30 " XXI-2 -- 52 48 52 Present invention 
31 " -- Polyethylene 
51 48 48 Present invention 
32 " XXI-4 Polystyrene 
51 48 50 Present invention 
33 61 -- -- 55 51 50 Present invention 
34 " XXI-2 -- 54 50 54 Present invention 
35 " -- Polymethaacrylate 
54 51 51 Present invention 
36 " XXI-4 Styrene-butadiene 
53 50 53 Present invention 
copolymer 
37 63 -- -- 54 50 49 Present invention 
38 " XXI-2 -- 53 50 52 Present invention 
39 " -- Nitrocellulose 
52 49 48 Present invention 
40 " XXI-4 Chlorinated paraffin 
52 49 51 Present 
__________________________________________________________________________ 
invention 
Comparative dyes 
##STR106## 
##STR107## 
REFERENCE EXAMPLE 1 
Light stability of methine dyes (2), (49) and (50) of the invention were 
examined. 
As comparative dyes, polymethine-cyanine dyes symmetrical with respect to 
benzothiazole A-1, A-2, A-3, A-4 and A were used. 
##STR108## 
EXPERIMENTAL CONDITIONS 
Measuring apparatus 
Light irradiation: CRM-FA Xe lamp irradiation spectroscope manufactured by 
NIPPON BUNKO CO., LTD. 
Quantitative determination: 340 type spectrophotometer manufactured by 
HITACHI, Ltd. 
Measuring condition 
Light irradiation wavelength: .lambda.max. of each dye except (50), A-4 and 
A-5 where light irradiations were each conducted at 704 nm 
Solvent: Methanol 
Dye density: 1.times.10.sup.-5 moVl 
Data treatment 
E: Energy absorbed by a dye (erg/mol) 
E=light energy which incomed in the cell (erg/cm.sup.2) 
x absorption coefficient (10.sup.3 cm.sup.2 /mol) 
E1/2: Light energy absorbed by a dye when dye density was reduced to 
one-half its initial value (erg/mol) 
______________________________________ 
Light stability of dyes (2), (49) and (50) of the invention 
Dye .lambda. max (nm) 
E 1/2 (.times. 10 .sup.17 erg/mol) 
______________________________________ 
(2) 574 319.5 
(49) 674 155.9 
(50) 774 173.3 
______________________________________ 
Light stability of comparative dyes A-1, A-2, A-3 and A-4 
Dye .lambda. max (nm) 
E 1/2 (.times. 10.sup.17 erg/mol) 
______________________________________ 
A-1 423 16.6 
A-2 555 67.2 
A-3 650 1.6 
A-4 756 0.1 
______________________________________ 
Light stability of comparative dye A 
Dye .lambda. max (nm) 
E 1/2 (.times. 10.sup.17 erg/mol) 
______________________________________ 
A 746 8.5 
______________________________________ 
As is seen from the abovedescribed, dyes (2), (49) and (50) of the 
invention each have light stabilities much higher than those of the 
comparative dyes, and are excellent as dyes for optical discs. 
Optical information recording media of the invention have adequate 
recording characteristics having high C/N, and have high stabilities 
against long-term preservation or against long-time reading.