Charge transfer salts and uses thereof

An electrochemical color change cell incorporating as a color changing agent intramolecular charge transfer salt or an intermolecular charge transfer salt. The intermolecular charge transfer salts and the intramolecular charge transfer salts have a plurality of oxidation states and a wide variation in color change. The intermolecular and intramolecular charge transfer salts preferably contain a violene moiety and a moiety having a carbonyl group conjugated to an aromatic moiety. The intramolecular charge transfer salts have a stable covalent radical-anion/radical-cation configuration. The intermolecular charge transfer salts have a stable ionic radical-anion/radical-cation configuration.

FIELD OF THE INVENTION 
This invention relates to intramolecular and intermolecular charge transfer 
salts and uses thereof in particular in electrochemical color changing 
cells, in particular this invention relates to electrochemical color 
changing cells wherein the color changing agent is selected from the 
intramolecular and intermolecular charge transfer salt. 
BACKGROUND OF THE INVENTION 
Electrochemical display devices of various types are generally well known 
and have come into extensive use in products such as digital display 
watches and video game display panels. Typically, the display effect in 
such devices is achieved by changing the electrical potential of a display 
electrode relative to a counter electrode in the device to cause a film or 
a fluid filled cell on the display electrode to electrochemically change 
color. Such electrochemical display devices are superior to either the 
type of emitting diode or plasma display panels that preceded them in 
development, because they require substantially less power to achieve the 
display function. While liquid crystal display devices have been developed 
with lower power requirements than those of light emitting diodes and 
plasma display panels, they have other inherent disadvantages. For 
example, the visual effect achievable from liquid crystals is severely 
limited by the viewing angle, i.e. if viewed from an angle several degrees 
away from an axes orthogonal to the plane of the display surface the 
visibility of this display is significantly decreased. Also, liquid 
crystal displays have essentially no residual memory function within the 
liquid materials. 
In the earliest electrochemical display devices, a color change was 
typically affected between a single dark color and a white or yellowish 
color, but no other variations in color were achievable. The 
electrochemical color change cells of the present invention have a wide 
color variation. 
Electrochemical display devices are expected to have a bright future since 
the color of indication is brilliant, necessary voltage and current are 
small and there is no restriction on the observation angle. 
Applicants have discovered unique types of electrochemical compounds. 
Applicants have synthesized an intramolecular charge transfer salt (which 
is described herein below) having multiple oxidation states which also 
shows a wide variation in color change and wide variation in the 
ultraviolet absorption. Applicants have also discovered for the first time 
intermolecular charge transfer salts (which is described herein below) 
including as an acceptor, a constituent, having a carbonyl group 
conjugated to an aromatic moiety. 
An intramolecular charge transfer salt is a covalent compound containing a 
moiety having a negative charge and an unpaired electron (radical-anion) 
and moiety having a positive charge and an unpaired electron 
(radical-cation) on the same molecule. An intramolecular charge transfer 
salt is schematically represented in FIG. 15. Covalent compound 220 has a 
moiety 222 which has a negative charge and an unpaired electron 224. 
Moiety 222 is the radical-anion. Covalent compound 220 has a moiety 226 
which has a positive charge and an unpaired electron 228. Moiety 226 is 
the radical-cation. The article in J. Am. Chem. Soc. 1983, 105, 4468-4469 
to J. Becker et al. and the article in Chemistry Of Materials, 1989, 1, 
412-420 to J. Becker et al. describe expected benefits of intramoleculer 
charge transfer salts and reports some experimental data on a model 
system. However, the articles of Becker et al. do not teach or suggest the 
synthesis of an intramolecular charge transfer salt. 
In recent years there has been an extensive amount of work on 
intermolecular charge transfer salts. This work is reviewed in the 
following articles; NATURE Vol. 109 May, 1984, p. 119, entitled "Organic 
Metals" to Bryce et al.; Accounts of Chemical Research, Vol. 12, No. 3, 
March, 1979, J. B. Torrance; The Organic Solid State, Jul. 21, 1986, C & 
EN p. 28, D. O. Cowan et al. The most highly studied intermolecular charge 
transfer salts are salts of TCNQ (tetracyano-p-quinodimethane), in 
particular the intermolecular charge transfer salt of TCNQ with TTF 
(tetrathiafulvalene). The TTF-TCNQ salt shows metallic-like conductivity. 
The prior art, however, does not teach nor suggest an intermolecular 
charge transfer salt including a compound having a carbonyl group 
conjugated to an aromatic moiety as an electron acceptor constituent. As 
used herein, an electrical conductor includes a material which is a 
semiconductor and a metallic conductor. 
An intermolecular charge transfer salt is schematically represented in FIG. 
16. Ionic compound 230 has anionic constituent 232 which has a negative 
charge and an unpaired electron 234. Constituent 232 is the radical-anion. 
Ionic compound 230 has cationic constituent 236 which has a positive 
charge and an unpaired electron 238. Constituent 236 is the 
radical-cation. Gap 240 schematically represents the absence of a covalent 
link or bond between the radical-anion constituent 230 and the 
radical-cation constituent in the ionic compound 230 and indicates the 
ionic interaction between the radical-cation and radical-anion. 
It is an object of this invention to provide an electrochemical color 
change cell containing an intramolecular charge transfer salt as a color 
changing agent. 
It is another object of the present invention to provide an electrochemical 
color change cell having as color change agent an intermolcular charge 
transfer salt containing a constituent having a carbonyl group conjugated 
to an aromatic moiety. 
It is another object of the present invention to provide an intermolecular 
charge transfer salt compound. 
It is another object of the present invention to provide intramolecular 
charge transfer compound containing a constituent having a carbonyl group 
conjugated to an aromatic moiety. 
These and other objects, features and advantages of the present invention 
will be readily apparent to those of skill in the art from the following 
more detailed description of the preferred embodiments and the figures 
appended thereto. 
SUMMARY OF THE INVENTION 
A broad aspect of the present invention is an electrochemical color change 
cell having an intramolecular charge transfer salt as the color change 
agent. 
Another broad aspect of the present invention is an intramolecular charge 
transfer salt which is a covalent compound capable of having at least one 
radical-cation moiety covalently bonded to at least one radical-anion 
moiety. 
In a more particular aspect of the present invention, the intramolecular 
charge transfer salt contains a violene or cyanine moiety and a moiety 
containing a carbonyl group conjugated to an aromatic moiety. 
Another broad aspect of the present invention is an electrochemical color 
change cell having an intermolecular charge transfer salt containing a 
constituent having a carbonyl group conjugated to an aromatic moiety as an 
anionic constituent as color change agent. 
Another broad aspect of the present invention is an intermolecular charge 
transfer salt containing a constituent having a carbonyl group conjugated 
to an aromatic moiety as an anionic constituent. In another more 
particular aspect of the present invention, the intermolecular charge 
transfer salt contains a bisimide anionic constituent and a violene 
cationic constituent.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
As shown in FIG. 1 in a container 2, at least a part of which is 
transparent, for example, of glass, clear plastic and the like, which 
contains electrochromic substance 4, a solution in the liquid phase, gel 
phase or solid phase, a pair of chemically stable electrodes, namely, an 
indication electrode 6 and a counter electrode 8 disposed within container 
4 with a specific gap between electrode 6 and 8. In the preferred 
embodiment the gap between electrodes 6 and 8 was filled with an 
electrochromic solution 4. However, electrochromic displays can be formed 
with polymeric materials and solid materials as described in U.S. Pat. No. 
4,571,029 to Skotheim et al. the teaching of which is incorporated herein 
by reference and in U.S. Pat. No. 4,573,768 to Hirai, the teaching of 
which is incorporate herein by reference. The electrodes 6 and 8 are 
connected to a variable DC power source 10 to control the potential 
between electrodes 6 and 8 and thereby the color of the electrochromic 
cell of FIG. 1. Optionally the electrochromic cell can have a separator 12 
between the indication electrode 6 and the counter electrode 8. The 
separator can be separators commonly used in the art in electrolytic 
cells, for example, a fritted glass plate (preferably having from 4-8 
micron porosity), a salt bridge and a semipermeable membrane, for example, 
a film of Nafion.RTM. DuPont. U.S. Pat. No. 4,183,631 to Kondo et al. 
teaches an electrochromic display device using a separator. The teaching 
of Kondo et al. is incorporated herein by reference. U.S. Pat. No. 
4,141,876 to Arenallo et al. is an example of an electrochromic display 
cell not using a separator. The electrochemical cell which is 
schematically shown in FIG. 1 can be used in the electrochromic devices of 
U.S. Pat. Nos. 3,864,589; 4,146,876; 4,008,950; 4,141,236 and 4,501,472 
described herein below the teaching of each of which is incorporated 
herein by reference. 
Electrochemical displays are known in which a plurality of separate 
segments or display elements are individually energized to provide a 
desired display characteristic. Such an arrangement is disclosed in U.S. 
Pat. No. 4,008,950 to Chapman et al. The Chapman display contains 
individually sealed cavities which contain an electrochemical fluid. Each 
display element is individually controlled by a pair of electrodes in 
contact with the fluid within each cavity. 
U.S. Pat. No. 3,864,589 to Schoot et al. describes an electrochemical 
display device in which an elongated horizontally extending 
electrochemical fluid cavity is provided for each of a plurality of 
electrodes. A plurality of vertically oriented, horizontally spaced 
individual display element cavities extend in communication with each 
elongated fluid cavity and electrodes are provided to form a matrix 
display in which individual electrochemical filled cavities extend between 
a matrix of row and column electrodes but with each of the individual 
cavities extending into communication with the elongated horizontally 
extending fluid cavity so that all individual cavities can be filled by 
filling a small number of elongated row cavities. This arrangement 
provides coincident matrix selection of the individual display elements to 
reduce the complexity of the electrical drive circuit by eliminating the 
need for a separate individually controlled electrical connection for each 
display element. 
U.S. Pat. No. 4,146,876 to Arellano et al. describes a matrix addressed 
electrochromic display which includes a first and second spaced part of 
opposed plate of panels, a dielectric space of peripherally sealing the 
panels to provide an interior cavity therebetween to define a display 
region, an electrochromic fluid filling interior cavity, a plurality of 
parallel rows and columns of electrodes disposed in the mating surfaces of 
the first and second panels respectively and a low output impedance 
electrical refresh circuit coupled to electrically energize the electrodes 
in a repetitive matrix selection pattern to provide a selected dot matrix 
display. 
Electrochromic displays have many other uses for example, in U.S. Pat. No. 
4,141,236 to Ellington describes a shock absorber coupled to an integrated 
circuit to measure the force/velocity characteristic of the shock absorber 
when the characteristic falls outside a predetermined value, the circuit 
delivers an electrical output to an electrochromic color change cell to 
indicate failure of the shock absorber. U.S. Pat. No. 4,501,472 to 
Nicholson et al. describes a tunable electrochromic filter using an 
electrochromic cell. The electrochromic cells described in the present 
invention have a wide variation in color change and are therefore useful 
as an electrochemically tunable optical filter. Moreover, the 
electrochemical materials of the present invention have a wide variation 
of ultraviolet absorption and are therefore useful as a ultraviolet 
filter. 
The preferred electrochemical solutions according to the present invention 
include an intermolecular charge transfer salt in a solvent. Examples of 
types of solvents are nitriles, nitro compounds, amides, cyclic amides, 
amines, esters, cyclic esters, carbonates, oxides and sulfo compounds. 
This list is exemplary only and not limiting. The following is a 
exemplarly list of solvents acetonitrile, N,N-dimethylformamide, 
N-methylformamide, N,N-diethylformamide, N-ethylformamide, 
N,N-dimethylacetamide, N-methyl-2-pyrrolidone, hexamethylphosphoramide, 
propylene carbonate, ethylene carbonate, .gamma.-butyrolactone, 
dimethylsulfoxide, acetone, sulfolane, water and alcohols. 
In addition, the electrochemical solutions will include in the solution a 
supporting electrolyte and preferably a supporting electrolyte salt that 
contains as cation a member from one of the following groups: 
tetraalkylammoniu, tetraalkylphosphonium, alkali metal, 
aryl-alkylammonium, aryl-alkylphosphonium, or chelated metal. The 
preferred tetraalkylammonium group is tetrabutylammonium, but other 
tetraalkyls with alkyl group being methyl, ethyl, propyl, isopropyl, 
pentyl, hexyl, or mixed alkyl thereof can be employed if desired. An 
example of a typical aryl group is phenyl and an aryl-alkylammonium is 
benzyltributylammonium. An example of a chelated metal cation is potassium 
18-crown-6. The supporting electrolyte salt preferably contains as anion 
one of the following: tetrafluoroborate, hexafluorophosphate, aryl 
sulfonate, perchlorate, or halide such as bromide or iodide. 
Because organic charge transfer salts contain redox couples they are 
candidates for color active agents in electrochromic devices. Organic 
charge transfer salts have been of interest in recent years, since the 
discovery of the metallic conductivity of the TTF-TCNQ ionic 
intermolecular charge transfer salt, as reported in J. Am. Chem. Soc. 
1973, 95, 948-949 by Ferraris et al. and in Solid State Commun. 1973, 12, 
1125-1132 by Coleman et al. 
The TCNQ radical anion forms organic semiconductors with a large number of 
cations. For example, K.sub.+ and N-methylquinolinium (NNQn.sup.+) salts 
with TCNQ have room temperature conductivities 
.perspectiveto.5.times.10.sup.-4 and .perspectiveto.10.sup.-6 ohm.sup.-1 
centimeters.sup.-1 respectively. The cations in these intermolecular or 
ionic charge transfer salts are electron donors. 
TCNQ has been found to form a few compounds with conductivities as high as 
10.sup.+2 ohms.sup.-1 cm.sup.-1. Many of these salts have a 1:2 ratio of 
cation to TCNQ, such as Et.sub.3 NH-(TCNQ).sub.2, but a few form 1:1 salt. 
A primary example is N-methylphenazinium, NMP-TCNQ. 
Substantial increase in the conductivity of intermolecular TCNQ salts was 
discovered in the prior art. It was found that the high conductivity is 
associated with crystal structures in which the intermolecular TCNQ salts 
are packed face to face, like a deck of playing cards, with segregated 
stacks of cations and TCNQ anions. FIG. 12 schematically shows such a 
stack where D represents the donor or cation and A represent the acceptor 
or anion. In an intermolecular charge transfer salt the dashed lines in 
FIG. 12 represent an ionic interaction between discrete cations and 
anions. In an intramolecular charge transfer salt the dashed line 
represents covalent bonding between the donor and acceptor parts of a 
covalently linked molecule. 
The .pi.-overlap and charge-transfer interaction between adjacent molecules 
in the stacking direction z are strong, causing therein unpaired electrons 
to be partially delocalized along one of these one dimensional molecular 
stacks and enabling them to conduct in that direction. The .pi.-bonds are 
represented in FIG. 12 by the dotted lines between the stacked D's and the 
stacked A's. Between adjacent donor and acceptor molecules there is a 
transfer of charge. The donor molecule transferring either an entire 
electron or a fractional part of an electron to the acceptor. In FIG. 12 
the degree of electron transfer is designated by the symbol .rho., which 
has a value between 0 and 1. For a value of .rho. equal to 0 there is no 
transfer of an electron from the donor to the acceptor. For a value of 
.rho. equalling to one there is complete transfer of an electron to the 
acceptor. For a value of .rho. between 0 and 1 there is partial transfer 
of the electron from the donor to the acceptor. 
The overlapping .pi. bonds between adjacent donors and between adjacent 
acceptors form energy bands in similar fashion to an energy band in solid 
state materials. When .rho. is either 0 or 1 for a crystallized material 
represented by FIG. 12 the material has energy bands either completely 
filled or completely empty of electrons and is therefore, either an 
insulator or semiconductor depending upon the energy separation between 
the highest completely filled energy band and the lowest completely empty 
energy band. When .rho. has a value between 0 and 1 which corresponds to 
partial electron transfer the highest energy band which contains electrons 
is generally partially filled and therefore corresponds to a metallic like 
conductor. 
In an article in J. Am. Chem. Soc. 1983, 105, 4468-4469 to Becker et al., 
the potential benefits of an intramolecular charge transfer salt over an 
intramolecular transfer salt have been described. However, Becker does not 
describe the actual synthesis of an intramolecular charge transfer salt. 
The benefits of an intramolecular charge transfer salt as pointed out by 
Becker et al. is to design efficient organic conductors which are composed 
of donor (D) and acceptor (A) moieties by achieving the following 
necessary conditions; (a) enforce a segregated mode of stacking (. . . DD 
. . . .parallel. . . . AA . . . ) in the solid state; (b) control the D:A 
stoichiometry; (c) encode ab initio the desired degre of electron transfer 
(.rho.) into the molecular unit; (d) stabilize the delocalized state, . . 
. D.sup..rho.+ D.sup..rho.+ . . . .parallel.A.sup..rho.- A.sup..rho.- . . 
. , below the localized ones, e.g., . . . D.sup.+ D . . . 
.parallel.A.sup.- A . . . ); (e) permit and control the degree of 
interchain coupling. Becker points out that the systematic control of 
these conditions will allow the preparation of organic conductors with 
predesigned properties. In the conditions (a) and (d) the segregated mode 
stacking is shown as . . . DD . . . this represents the vertical stack of 
D's in FIG. 12. Also, the . . . AA . . . represents the vertical row of 
A's in FIG. 12. The double vertical lines separating the D's and the A's 
corresponds to the bonding between the D's and the A's, shown in FIG. 12 
as a dotted line. 
Becker et al. refers to an archetypal molecular unit Dm-An which contains 
both donor and acceptor moieties in a prefixed stociometric ratio (n:m), 
which is potentially endowed with the necessary properties that can be 
calculated to meet the requirements of conditions b to d above. 
Becker reports a model archetypal molecular unit, 
2,5-dibenzyl-7,7,88-tetra-cyano-p-quinodimethane (DBTCNQ). Becker points 
out that this molecule contains a weak donor (e.g. phenyl), and that this 
material was expected not to be a ground state conductor. Becker further 
points out that this compound shows promise for the strategy underlined in 
criteria (a)-(e). Therefore it is clear from the teaching that Becker has 
not fabricated an intramolecular charge transfer salt. 
The model compound of Becker consists of two benzene rings linked to a TCNQ 
acceptor. The reason why this compound is not an intramolecular charge 
transfer salt is that the reduction potential of the benzene 
radical-cation is too positive relative to the reduction potential of the 
TCNQ moiety. This means that it is not energetically favorable to transfer 
an electron from the benzene ring to the TCNQ moiety. The potentials in 
question are: 
EQU TCNQ(0)+e.sup.- .fwdarw.TCNQ(-)+0.127V vs SCE 
Reference: "Electrochemical Methods" by A. J. Bard L. R. Faulkner. John 
Wiley and Sons, New York, 1980. 
Toluene(+)+e.sup.- .fwdarw.Toluene(0)+2.0V vs SCE 
Reference: W. C. Neikam, et al., J. Electrochem. Soc. 111, 1190 (1964). 
In other words if it were possible to prepare the Becker et al. molecule as 
the radical-cation/radical-anion, it would immediately go back to the 
uncharged state because the TCNQ radical-anion is almost 2 V more strongly 
reducing than is the neutral phenyl ring. The redox potential of a toluene 
is used instead of the potential for a benzene ring since toluene is a 
better match for the substituted in benzene in the Becker molecule. 
FIG. 13 and FIG. 14 are schematic representations of the relationship of 
the redox potentials of the donor and acceptor moieties of an 
intermolecular charge transfer salt and an intramolecular charge transfer 
salt. FIG. 13 shows two peaks on a plot which represent two distinct redox 
couples. The vertical axis is an arbitrary scale of density of electronic 
states. The horizontal axis is an arbitrary scale of electric potential 
(the scale of energy E is also indicated). Since E is equal to 
-.vertline.e.vertline. P, the energy scale is inversed to that of the 
potential scale. A redox couple is an energy location on a molecule which 
is capable of reversibly receiving or giving up an electron. For an 
intramolecular charge transfer salt the redox couples 200 and 202 would be 
different moieties on the same molecule. For an intermolecular charge 
transfer salt the redox peaks 200 and 202 would represent redox couples on 
different molecules. The redox couple on each molecule has a molecular 
orbital with an energy level into which the electron is deposited. The 
spreading in the energies of the redox couples 200 and 202 arises because 
in a collection of molecules each electron is added to a molecular orbital 
of a distinct molecule. Energies of the remaining unoccupied molecular 
orbitals of other molecules are affected by the filled molecular orbitals 
and increase in energy. This causes the spread in energy of the redox 
couples. If redox couple 200 represents a collection of molecules 
containing an electron in the redox couple these molecules are potential 
donors. Assuming that the redox couples 202 are unoccupied by electrons 
since they are at a potential more positive than the redox couple 200 or 
in other terms at a lower energy than the redox couple 200 the electrons 
in the redox couple 200 can transfer to the redox couple 202. This 
corresponds to complete electron charge transfer referred to herein and 
above. If redox couple 202 is completely occupied with electrons and redox 
couple 200 is completely empty of electrons, since redox couple 202 is at 
a potential more positive of redox 200 or in other words since redox 
couple 202 is at a lower energy level than redox couple 200 electrons in 
redox couple 202 will not transfer to redox couple 202. This corresponds 
to the condition of no electron transfer referred to herein and above. 
FIG. 14 represents the condition where the redox couples 200 and 202 
overlap which is indicated by the shaded region 203 in FIG. 14. If redox 
couple 200 is completely filled with electron and redox couple 202 is 
completely empty, redox couple 200 represents a potential electron donor. 
Since redox couple 202 is at a potential more positive than redox couple 
200 the electrons in redox couple 200 can transfer to redox couple 202. 
However, because of the overlap region 204 electrons can remain in redox 
couple 200. This corresponds to the condition of partial electron transfer 
since the electron can occupy both redox couples 200 and 202. For the 
condition where redox couple 202 is filled with electrons and redox couple 
200 is completely empty of electrons, redox couple 202 is a potential 
electron donor. However, since redox couple 202 is at a potential more 
positive of redox couple 200 most of the electrons remain in redox couple 
202. However, because of the overlap region 203 the electrons can occupy 
redox couple 200. This also corresponds to the condition of partial 
electron transfer. The degree of partial electron transfer depends upon 
the amount of overlap of the couples 200 and 202. 
The applicants are the first to synthesize an intramolecular charge 
transfer salt for which it is contemplated that partial electron transfer 
between an electron donor moiety and an electron acceptor moiety on the 
same covalent molecule can be achieved in the solid and polymeric to form 
ionic, semiconducting and metallic state. For the sake of clarity, 
synthesis of, and use of the intramolecular charge transfer salt will be 
described in terms of a preferred embodiment containing a viologen donor 
and an aromatic bis-imide acceptor, which has five distinct oxidation 
states and four redox couples which has a corresponding wide variation in 
color change which makes it useful for electrochromic display devices. The 
synthesis can generally be described as reacting a monoalkylated viologen 
with an unsymmetrical bis-imide containing a leaving group suitable for 
undergoing a displacement reaction. The bis-imide is preferably in excess, 
most preferably 0.5M excess. It is contemplated that this method can be 
generalized to violenes and cyanines and to compound having an carbonyl 
group conjugated to an aromatic moiety. It will be readily apparent to the 
artisan that this method generalizable to violenes and cyanines reacted 
with compounds having a carbonyl group conjugated to an aromatic moiety. 
Generally, organic molecules having multiple redox couples show multiple 
color variation on electrochemically populating and depopulating redox 
couples. The viologen bis-imide intramolecular compound described herein 
is unusual in that it has five oxidation states permitting a very wide 
variation in color change. Applicants have also discovered that an 
electrolyte solution containing a compound having a viologen moiety and 
containing a compound having a bis-imide moiety when there is no covalent 
link between these two molecules also shows five oxidation states which 
also shows a very large variation in color change. The violene, family of 
compounds is described in Pure Appl. Chem. 1967, 15, 109-122 to Hunig and 
in Top. Curr. Chem. 1980, 92, 1-44 to Hunig et al. The teachings of both 
of the Hunig articles are incorporated herein by reference. Violenes are 
preferred. The most preferred donor embodiment is a viologen which is a 
member of the violene family of compounds. The most preferred viologen is 
ethyl viologen which has the following structural formula where I.sup.- is 
an iodide ion 
##STR1## 
The bis-imide material of this preferred embodiment is 
N,N'-dibutylpyromellitimide which has the following structural formula 
where Bu=n-butyl or CH.sub.3 CH.sub.2 CH.sub.2 CH.sub.2 in Compound 15: 
##STR2## 
The violene family of compounds exist in three distinct oxidation states 
and therefore has two redox couples. The bis-imides also have three 
distinct oxidation states and therefore two redox couples. The combination 
of the violene and bis-imide either in a covalent linked compound or in an 
intermolecular ionic compound shows five oxidation states and four redox 
couples. 
The linked compound has the following structural formula where OMS=CH.sub.3 
SO.sub.3 .crclbar. or mesylate ion or methylsulfoxy ion in compound 16: 
##STR3## 
The various oxidation states of the violene and bis-imide family of 
compounds are based on their complementary charges and on the overlap of 
their reduction potential as shown in the Table for ethyl viologen (14) 
and N,'N-dibutylpyromellitimide (15). As can be seen from the Table there 
is an overlap in the reduction potentials of compounds 14 and 15. Such an 
overlap in reduction potential can lead to partial electron transfer as 
described herein above which can lead to electrical conductivity in the 
solid state. 
TABLE 
______________________________________ 
Reduction Potential for 14 and 15 
Compound .sup.1 E.sub.1/2 
.sup.2 E.sub.1/2 
______________________________________ 
14 -0.370 -0.752 
15 -0.685 -1.392 
______________________________________ 
Reduction potentials measured by cyclic voltammetry vs. SCE at 0.5 mM in 
DMF/0.1 M Bu.sub.4 NBF.sub.4. 
The following sequence of equations represents the reversible addition of 
four electrons to the linked compound 16. The color of each oxidation 
state is listed. The X.sup.- 's and M.sup.+ 's are counterions to provide 
local charge neutrality. FIG. 4 and FIGS. 6 to 10 show UV-VIS (ultraviolet 
visible spectroscopy) spectra or corresponding to the stages of reduction 
of linked compound 16 as it accepts a total of four electrons. FIG. 2 is a 
CV (cyclic voltammegram) of the compound of equation 16. The CV and UV-VIS 
are measurements commonly practiced in the art. M.sup.+ is Bu.sub.4 
N.sup.+ or Et.sub.4 N.sup.+ (i.e. tetraalkylammonium ion 5) X.sup.- is 
OMs.sup.- or I.sup.- or BF.sub.4.sup.-. 
##STR4## 
A molecule in which both moieties 14 and 15 are incorporated would first 
add, under reduction conditions, an electron to the viologen unit, 
generating a radical-cation. Then, because the reduction potential for 
adding a first electron to the imide is 67 mV more positive than that for 
adding another to the viologen, the second electron would reduce the imide 
unit leading to a radical-cation/radical-anion. This has been explored 
using cyclic voltammetry (CV) and by bulk electrolysis monitored 
spectroscopically. Both the compound 16, in which two moieties are 
covalently linked and an equimolar mixture of 14 and 15 have been studied. 
The CV of the linked compound 16 is shown in FIG. 2. The CV for the 
mixture of compound 14 and 15 is shown in FIG. 5. The CV's for both the 
linked compound and the mixture can be readily understood as a 
superposition of the CV of the imide on that of the viologen. In the 
cyclic voltammograms of FIG. 2 and FIG. 5 the voltage of a working 
electrode is scanned from 0 volts (vs. SCE) to a negative potential which 
is insufficient to electrolyze the electrolyte. The voltage is then ramped 
back to 0. The lower part of the curves corresponds to the reduction of 
the redox couple or adding electrons thereto; the upper part of the curve 
corresponds to the oxidation of redox couples or extracting the electrons 
therefrom. Referring to FIG. 2, peak 204 corresponds to the transition 
from equation 17 to equation 18, peak 206 corresponds to a super position 
of the transition from equation 18 to equation 19 and from equation 19 to 
equation 20, peak 208 corresponds to the transition of equation 20 to 
equation 21, peak 210 corresponds to the transition from equation 21 to 
equation 20, peak 212 corresponds to the super position of the transition 
from equation 20 to equation 19 and the transition of equation 19 to 
equation 18, and peak 214 corresponds to the transition from equation 18 
to equation 17. A similar analysis corresponds to FIG. 5. Note that the 
middle peak 206 and 212 in FIG. 2 and 216 and 218 in FIG. 5 are roughly 
twice the height of the other two peaks because it is the result of the 
two redox couples--the first imide reduction and the second viologen 
reduction--which are not well resolved in the CV. 
Bulk electrolysis of compound 16 in dimethylformamide (DMF) was done in a 
glove box, and samples were removed periodically for UV-VIS spectroscopy. 
Electrolysis at -0.6 V (vs. standard calomel electrode, SCE) generated the 
characteristic spectrum of the viologen radical-cations. The solution was 
then reduced further until a rest potential of E.sub.soln =-0.70 V was 
obtained, which resulted in a species showing absorptions for both the 
viologen radical-cation and the pyromellitimide radical-anion which is 
shown in FIG. 3. Further electrolysis to E.sub.soln =-0.75, -0.79 -1.40 V 
leads first to the disappearance of the radical-cation absorption and then 
to the appearance of absorptions of the neutral quinoid form of the 
viologen, then to the disappearance of the pyromellitimide radical-anion 
absorption in appearance of the dianion absorption. Thus, the 
electrochemistry of the compound of equation 16 traverses five states: 
colorless dicatation, blue radical-cation, blue-green 
radical-cation/radical-anion, green radical-anion and rose dianion. 
The radical-cation/radical-anion is an unusual structure for an organic 
molecule in its ground state, i.e. a state not populated by a photo 
excited state. From both the CV and UV-VIS results, it is clear that there 
is little interaction between the unpaired electrons as might have been 
predicted from the length and relative rigidity of the aralkyl linkage. 
Bulk electrolysis of the viologen 14 was performed until it was completely 
converted to the neutral form. Under ambient conditions the stable form of 
the viologen 14 is the dicationic form where the two positive changes are 
balanced by two anions which in compound 14 is two iodide ions or 
2I.crclbar.. At this point, addition of an equal or more amount of the 
un-reduced imide 15 rapidly resulted on a UV-VIS spectrum (as shown in 
FIG. 11) very similar to that of the doubly reduced form of the compound 
16. This is represented by the following equation: 
EQU 14.sup.0 +15.sup.0 .fwdarw.14.sup.+. +15.sup.-. 
By confirming that the radical-cation/radical-anion pair can be generated 
from the pair of compounds in a neutral state, which are clearly 
electronic ground states, this last experiment validates the description 
of the doubly reduced linked compound in a ground state 
radical-cation/radical-anion. In the sequence of equations 17-21, the 
bis-imide moiety acts as an acceptor and the viologen moiety acts as a 
donor. For the purpose of the present application an intermolecular charge 
transfer salt refers to all the oxidation states as represented by 
equations 17-21. For the purpose of the present application, an 
intermolecular charge transfer salt corresponds to a corresponding full 
sequence of oxidation states for non-linked compounds which corresponds to 
those of equation 17-21. 
The present invention is not limited to five oxidation states but can 
include many more than five oxidation states. The redox potentials as 
shown in FIGS. 2 and 5 can be adjusted by different structural variations 
of the donor and acceptor moieties, for example, by forming substituted 
forms of the donor and acceptor moeity. Adjusting the redox potentials of 
compounds by forming structural variations are described in Proceedings Of 
The Symposium On Polymeric Materials For Electronic Packaging and High 
Technology Applications, Vol. 88-17, The Electrochemical Society Inc.; 
Pennington, N.J. pp 88-102, (1988) Viehbeck et al., the teaching of which 
is incorporated herein by reference, and in Metallized Polymers, ACS 
Symposium Series, American Chemical Society, Washington, D.C., in press 
exp. June 1990 to Viehbeck et al., the teaching of which is incorporated 
herein by reference. It is contemplated that such adjustments of the redox 
potentials can be done to achieve electrically conducting organic polymers 
in the solid state. 
The synthesis of a viologen bis-imide, in particular compound 16, will now 
be described. Electrochemical reduction of viologen bis-imide (16) led to 
five distinct redox states that were characterized by cyclic voltammetry 
and ultraviolet/visible spectroscopy. The ability of a bis-imide to accept 
one and two electrons to give radical-anion and a dianion, respectively, 
has been established by Viehbeck et al. as incorporated by reference 
above. There exists a whole family of compounds whose redox activity is 
exactly complementary to that of bis-imides. These compounds termed 
violenes as described above (for example, the dialkylbipyridinium salts) 
can exist in one of three states: dication, radical cation, and the 
uncharged state. A compound containing a bis-imide covalently attached to 
a dialkylbipyridinium salt could therefore exhibit five oxidation states. 
Of particular interest is the state where one end of the molecule exists 
as a radical-cation and the other a radical-anion--a highly unusual 
chemical structure. 
Pyromellitimides, in general, are very insoluble in most organic solvents. 
Thus pyromellitimide 2 was completely insoluble in all organic solvents 
tried. 
##STR5## 
Solubility of the viologen bis-imide 16 was a key to being able to 
characterize the molecule electrochemically. To achieve this, we resorted 
to an unsymmetrical pyromellitimide 3, which has an alkyl imide ring on 
one side and an aryl imide on the other. A longer chain alkyl, namely a 
butyl group, was used to help solubilize the planar structure. The aralkyl 
spacer between the viologen and bissimide provided a semi-rigid spacer to 
minimize electronic interaction between the two portions of the molecule. 
We chose to create the dissymmetry in 3 by a Diels-Alder reaction of 
N-butyl maleimide and 3,4-dicarbomethoxyfuran, aromatizing the Diels-Alder 
adduct with dilute acid; and, operating on the ester functionality to 
incorporate a differently substituted imide. However, aromatizing compound 
4 posed tremendous difficulty (Scheme 1). The four electron withdrawing 
groups in molecule 4 did not support carbocation formation conditions. 
Hence in spite of its strained structure, 4, was completely resistant even 
to strong acids. The exo nature of the Diels-Alder adduct also made it 
impossible to ring open the oxygen bridge using lithium diisopropylamide. 
##STR6## 
McMurry's deoxygenation methodology, (as described in Heterocycles 1983, 
20, 1985; Wong, H. N. C., the teaching of which is incorporated herein by 
reference) using low valent titanium species to deoxygenate 4, produced 
low yields of the aromatized product. However, the reaction works very 
well on 1,4 cyclohexadiene systems. We therefore chose molecule 5 as our 
key intermediate towards the synthesis of the viologen bisimide. The 
difference in reactivity between benzyl esters and methyl esters was used 
to create the dissymetry needed in the imide portion of the molecule. 
Dibenzyl acetylenedicarboxylate was prepared using the procedure described 
in J. C. S. Perkin Trans I 1973, 23, 2024 to G. Low et al. the teaching of 
which is incorporated herein by reference. The formation of dibenzyl ether 
in the esterification reaction was minimized by carrying out the 
distillation of benzyl alcohol rapidly. The dibenzyl has a low flash 
point. It is therefore recommened to cool the flask to room temperature 
before introduction of air into the system. The Diels-Alder reaction of 
dibenzyl acetylenedicarboxylate and 3,4-dicarbomethoxyfuran proceeded in a 
respectable yield of 50% (5 ). Deoxygenation of 6 using the McMurry's 
reagent (TiCl.sub.4 /LAH/NEt.sub.3) in dimethoxyethane (DME) led to a 60% 
yield of the pyromellitic tetraester 7. Using THF as the solvent led to 
considerable poly-THF formation under the reaction conditions. Thus 
changing the solvent from THF to DME raised the yield in the deoxygenation 
reported in the article of Wong referred to herein above, on the 
corresponding tetramethyl ester from 49% to 85%. 
Hydrogenolysis of the tetraester 6 proceeded in near quantitative yield to 
3,4-dicarbomethoxyphthalic acid 7. Acetic anhydride reflux of the phthalic 
acid 7 led to the formation of 3,4-dicarbomethoxyphthalic anhydride, 8, in 
a 75% yield. Imidization of the anhydride 8 had to be done with distilled 
butylamine and purified 8 used in an exact 1:1 ratio. Excess butylamine 
reacted with the esters under the imidization conditions to give the 
bis-butyl imide. The methyl esters were then cleaved using LiI in pyridine 
to the diacid 10 in a near quantitative yield. Using pyridine as the 
solvent which reacted with the methyl iodide formed in the reaction, 
forced the reaction in the forward direction leading to the high yield. 
The diacid was then dehydrated with acetic anhydride to give the anhydride 
11. The second imidization with 4-aminophenethyl alcohol proceeded 
smoothly to yield 3 (67%). The alcohol 3 was then converted to the 
mesylate 12 in spite of its sparing solubility in methylene chloride and 
most other solvents, using a dilute solution of the alcohol in methylene 
chloride and standard conditions for the reaction. 
Monoethylbipyridinium iodide was made by refluxing bipyridyl hydrate with 
ethyl iodide in acetonitrile as described in Tetrahedron, 1981, 37, 4185 
to I. Tabushi et al. the teaching of which is incorporated herein by 
reference. The final step in the synthesis, the displacement reaction of 
the mesylate in 12 by the nitrogen in the monoethylbipyridyl iodide, 
required a 0.5 mole excess of the mesylate in order for the reaction to go 
to completion. The yield on the last step was 65%. 
##STR7## 
Many variations are possible at the second imidization step. One important 
variation in particular is the identity and length of the spacer group 
between the bis-imide and violene moieties. Of particular interest are 
oxyethylene spacers of the indication that polyimides containing 
oxyethylene chains were unusually crystalline as described in Polymer 
Preprints, 1985, 26 (2), 287 to Harris, F. W. et al. 
Changes in the bis-imide and violene components will allow fine tuning of 
the reduction potentials. Varying these components in conjunction with 
varying spacer groups affects the redox and solid state properties of 
these materials. 
Solvents and reagents were reagent grade or better and were used as 
received except where otherwise noted. IR spectra were obtained on a 
Perkin Elmer 1310 spectrophotometer (KBr pellet unless otherwise 
indicated). The IR data include all absorptions in the region 3500-1500 
cm.sup.-1 but only the prominent absorptions in the region 1500-200 
cm.sup.-1. UV-Vis spectra were run on a Hewlett-Packard 8452A diode array 
spectrometer. Proton NMR were recorded on an IBM 270 MHz instrument at 
room temperature in acetone-d.sub.6 unless otherwise stated. Melting 
points were determined on a Fisher-Johns apparatus and are uncorrected. 
DIELS-ALDER ADDUCT 5 
A mixture of 1.2 g (4.1 mmol) dibenzyl acetylenedicarboxylate and 0.75 g 
(4.1 mmol) of 3,4-dicarbomethoxyfuran were refluxed (under argon) in 
xylene for 24 h. Removal of solvent by rotary evaporation, followed by 
preparative TLC (2 mm thick silica gel plates; EtOAc/Hexane, 1:4) gave 
0.96 g (50%) of the Diels-Alder adduct (the band corresponding to the 
lowest R.sub.f). Dibenzyl acetylenedicarboxylate (8%) was recovered (the 
band corresponding to the highest R.sub.f). Attempted purification of the 
Diels-Alder product by distillation led to retro-Diels-Alder reaction. 
Product 4 was a viscous syrup; IR (1% CHCl.sub.3 solution): 3030, 2960, 
1740, 1720, 1440, 1300, 1260, 1125 cm.sup.-1 ; .sup.1 H NMR: .delta. 
7.37(m, 10H, Ar H), 6.04 (s, 2H, CH) 5.21 (s, 4H, CH.sub.2, 3.7 (s, 6H, 
CH.sub.3). 
DIBENZYL 4,5-DICARBOMETHOXYPHTHALATE 6 
Twice-distilled 1,2-dimethoxyethane (DME) (once over CaH.sub.2 and then 
over K) was used for this experiment. A three-necked round bottomed flask 
was first thoroughly flushed with dry argon. TiCl.sub.4 (4 mL, 31 mmol) 
was syringed into the flask and cooled to 0.degree. C. DME (20 mL) was 
slowly syringed into the flask. A yellow solid separated. Lithium aluminum 
hydride (LAH, 120 mg, 3 mmol) was added very cautiously so as to avoid 
abrasion which can cause the LAH to ignite. The yellow solid dispersed, 
the color changed to green and finally to black. The cooling bath was 
removed. Triethylamine (1 mL, 7.2 mmol) was added and the contents of the 
flask were refluxed at 85.degree. C. for 15 min. The flask was then cooled 
to room temperature. The Diels-Alder adduct 4 (471.3 mg, 1 mmol) was added 
to the flask and the contents stirred at room temperature for 1.5 h. The 
reaction was worked up by adding 100 mL of ice water and extracting thrice 
with methylene chloride. Addition of excess water helps clarify the deep 
violet/blue color and helps in the separation of the two layers clearly. 
The organic extract was dried over magnesium sulfate and evaporated to 
give 430 mg of the product (93% crude yield). The flask containing the 
organic extract developed a white non removable deposit on walls due to 
titanium dioxide. Viscous liquid; IR (1% CHCl.sub.3 solution): 3040, 2960, 
1740, 1270, 1135, 1110 cm.sup.-1 ; .sup.1 H NMR .delta. 8.1 (s, 2H, Ar H, 
the ring having the four ester substituents), 7.42-7.38 (m, 10H, Ar H of 
the benzyl group), 5.27 (s, 4H, CH.sub.2), 3.89 (s, 6H, CH.sub.3). 
3,4-DICARBOMETHOXYPHTHALIC ACID 7 
A solution of 5 (260 mg, 0.56 mmol) in ethanol/ethyl acetate (20 mL, 3:1) 
containing 5% Pd/C (30 mg) was subjected to hydrogen at 60 psi in a Parr 
hydrogenator until the calculated amount of hydrogen was used up. The 
mixture was filtered through a bed of Celite and concentrated to yield 
156.3 mg (98.9%) of the phthalic acid. White solid; mp: 162-164; IR: 3100, 
2980, 1730, 1700, 1440, 1430, 1310, 1270, 1130, 1110, 800 cm.sup.-1 ; H 
NMR: .delta.8.11 (s, 2H, Aryl H), 3.91 (s, 6H, CH.sub.3). 
3,4-DICARBOMETHOXYPHTHALIC ANHYDRIDE 8 
In a 100 mL round bottomed flask fitted with a condenser closed with a 
calcium chloride tube, 156.3 mg (0.55 mmol) of 7 and 0.5 ml of acetic 
anhydride were placed. The contents of the flask were refluxed gently for 
15 min. On cooling white crystals appeared. The crystals were collected on 
a filter, washed with ether and purified by sublimation under high vacuum 
(0.05 torr) at an oil bath temperature of 130.degree. C. to yield 110 mg 
(75%) of the anhydride 8. White solid; mp: 178.5.degree.-179.5.degree. C.; 
IR: 3110, 3040, 2980, 1860, 1790, 1740, 1720, 1440, 1300, 1250, 1100, 910, 
900 cm.sup.-1 ; .sup.1 H NMR: .delta. 8.38 (s, 2H, Aryl H), 3.95 (s, 6H, 
CH.sub.3). 
IMIDE 9 
Distilled butylamine (0.075 mL, 0.05 g, 0.7 mmol) was added to a solution 
of (198.1 mg, 0.7 mmol) of 8 in dimethylformamide (DMF, 2 mL). The 
contents of the flask were stirred for half hour at room temperature and 
then refluxed for two hours at 150.degree. C. under argon. Removal of the 
solvent by high vacuum distillation followed by preparative TLC (2 mm 
thick silica gel; EtOAc/Hexane 1:1) led to 178.3 mg (75% yield) of the 
product (the band corresponding to highest R.sub.f). White crystals; mp: 
63.degree.-65.degree. C.; IR: 2960, 2780, 1775, 1740, 1730, 1720, 1710, 
1400, 1340, 1280 cm.sup.-1 ; .sup.1 H NMR: .delta. 8.1 (s, 2H, Aryl H), 
3.93 (s, 6H, CH), 3.67 (t, 2H, CH.sub.2 .alpha. to the N), 1.65 (quintet, 
2H, CH.sub.2 .beta. to the imide N), 1.35 (sextet, 2H, CH.sub. 2 .gamma. 
to the imide N), 0.92 (t, 3H, CH.sub.3). 
DIACID 10 
A pyridine (5 mL) solution of 9 (174.1 mg, 0.5 mmol) was heated under 
reflux in an argon atmosphere with 0.5 g (3.7 mmol) LiI for 2 h. The 
reaction mixture was cooled, the solvent evaporated, and finally water was 
poured into the flask and acidified to litmus with dilute HCl. The 
ethereal extract of this mixture was washed twice with 2N HCl, with brine 
containing small amounts of sodium sulfite to remove traces of iodine, 
dried over MgSO.sub.4, and evaporated to yield 155.6 mg (98% yield) of the 
diacid 10. Colorless solid; mp: turned brown at 120.degree. C., vaporized 
at 172.degree.-173.degree. C.; IR 3410, 3100, 2980, 1780, 1740, 1710, 
1400, 1370, 1140 cm.sup.-1 ; .sup.-1 H NMR .delta. 10.2 (br s, COOH), 8.12 
(s, 2H, aryl H), 3.68 (t, 2H, CH.sub.2 .alpha. to the N), 1.66 (quintet, 
2H, CH.sub.2 .beta. to the imide N, 1.38 (sextet, 2H, CH.sub.2 .gamma. to 
the imide N, 0.93 (t, 3H, CH.sub.3). 
ANHYDRIDE 11 
Diacid 10 (155.6 mg) and 0.5 mL of acetic anhydride were refluxed for 30 
min in a flask fitted with a condenser capped with a drying tube of 
calcium chloride. The flask was then cooled to room temperature and 112 mg 
(80%) of the product was collected by filtration. White solid; IR 3100, 
3050, 2980, 2965, 2880, 1860, 1780, 1700, 1405, 1300, 1280, 1180, 910, 620 
cm.sup.-1 ; .sup.1 H NMR .delta.8.42 (s, 2H, Aryl H), 3.73 (t, 2H, 
CH.sub.2 .alpha. to N), 1.65 (quintet, 2H, CH.sub.2 .beta. to the imide 
N), 1.36 (sextet, 2H, CH.sub.2 .gamma. to the imide N), 0.9 (t, 3H, 
CH.sub.3). 
BISIMIDE 3 
p-Phenethyl alcohol (29 mg, 0.2 mmol) was added to a solution of 58 mg (0.2 
mmol) of 11 in N-methylpyrrolidinone (1 mL). The contents of the flask 
were initially stirred at room temperature for 2 h, and then refluxed for 
5 h under argon. The solvent was removed by high vacuum distillation and 
the contents in the flask were dissolved in large volumes of methylene 
chloride (the product is virtually insoluble in all other solvents tried). 
The methylene chloride layer was washed 2N HCl, brine, and finally with 
satd NaHCO.sub.3 soln, dried over MgSO.sub.4, filtered and evaporated to 
yield 66.4 mg (67% yield) of the unsymmetrical imide 3. Off-white solid; 
mp: 290.degree. C. (condensation occurs on the microcover glasses), 
305.degree.-308.degree. C. (decomp.); IR: 3400, 2960, 2940, 1780, 1720, 
1700, 1400, 1190, 725 cm.sup.-1 ; .sup.1 H NMR (CDCl.sub.3): .delta. 8.63 
(s, 2H, Aryl H), 7.6-7.5 (AA'BB', 4H, para substituted aryl ring H), 5.68 
(br s, OH), 4 (t, 2H, C2.sub.2) alpha to hydroxy), 3.72 (t, 2H, CH.sub.2 
alpha to the N), 3 (t, 2H, CH.sub.2 alpha to the phenyl ring and beta to 
the hydroxy), 1.55 (quintet, 2H, CH.sub.2 beta to the imide N), 1.23 
(sextet, 2H, CH.sub.2 .gamma. to the imide N), 0.8 (t, 3H, CH.sub.3). 
MESYLATE 12 
A stirred solution of 64 mg (0.16 mmol) of 3 in 70 mL of methylene chloride 
was cooled under argon to -10.degree. C. and treated with 0.5 mL (363 mg, 
3.6 mmol) of triethylamine followed by dropwise addition of 0.3 mL (0.44 
g, 3.9 mmol) of methanesulfonyl chloride. The flask was stored at 
0.degree.-5.degree. C. overnight. The solution was poured into a sep 
funnel containing ice, washed successively with with 2N HCl, brine, and 
satd NaHCO.sub.3 soln; dried over MgSO.sub.4, filtered, and evaporated to 
give 71 mg (93% yield) of the mesylate 12. White solid; mp: decomposed to 
a black mass 150.degree.-200.degree. C.; IR: 2960, 2940, 1780, 1720, 1700, 
1170, 1090, 725 cm.sup.-1 ; .sup.1 H NMR (CDCl.sub.3): .delta. 8.3 (s, 2H, 
Aryl H), 7.35 (s, 4H, para-substituted aryl ring H), 4.39 (t, 2 H, 
CH.sub.2 .alpha. to OSO.sub.2 Mc grouping), 3.7 (t, 2H, C2.sub.2 .alpha. 
to N), 3.04 (t, 2H, CH.sub.2 .alpha. to phenyl ring), 1.63 (quintet, 2H, 
CH.sub.2 .beta. to imide N), 1.32 (sextet, 2H, CH.sub.2 .gamma. to imide 
N), 0.89 (t, 3H, CH.sub.3). 
VIOLOGEN BIS-IMIDE 16 
Monoethylbipyridinium iodide (REF) (32.3 mg, 0.1 mmol) was added to a 
solution of 71 mg (0.15 mmol) of mesylate 12 in DMF (1 mL). The contents 
of the flask were refluxed overnight at 138.degree. C. under a blanket of 
argon. DMF was removed by high vacuum distillation, and the product in the 
flask was stirred with 30 mL of methylene chloride to dissolve the excess 
mesylate 12. Filtration through a sintered glass funnel led to an yield of 
46 mg (60%) of the orange-red product. mp: &gt;250.degree. C.; UV (DMF): 250 
nm (.epsilon. 19,700), 402 nm (.epsilon.980); IR: 3440, 2920, 2960, 1770, 
1720, 1630, 1390, 1200, 1080, 840, 720 cm.sup.-1 ; .sup.1 H NMR 
(DMF-d.sub.7): .delta. 9.74 (AA'BB', 4H, Aryl H .alpha. to the positively 
charged N), 9 (overlapping AA'BB', 4H, aryl H .beta. to the positively 
charged N), 8.28 (s, 2H, Aryl H), 7.55 (AA'BB', 4H, para-substituted aryl 
ring H), 5.28 (t, 2H, CH.sub.2 alpha to N.sup.+ and methylene), 4.97 (t, 
2H, CH.sub.2 alpha to N.sup.+ and methyl), 3.67 (overlapping triplet, 4H, 
CH.sub.2 .alpha. to imide N and CH.sub.2 .alpha. to phenyl ring), 2.46 (s, 
3H, SO.sub.2 Me), 1.72 (t, 3H, CH.sub.3 of the ethyl group), 1.62 
(quintet, 2H, CH.sub.2 .beta. to imide N), 1.34 (sextet, 2H, CH.sub.2 
.gamma. to imide N), 0.91 t, 3H, CH.sub.3 of butyl group). 
The cyclic voltammogram obtained of a 1 mM solution of 1 in DMF with 0.1M 
tetrabutylammonium tetrafluoroborates the electrolyte at 50 mV/sec is 
shown in FIG. 2 (voltages were measured against SCE). 
The UV of the various species generated at the different potentials is 
shown by the side of the structure generated in FIG. 3. 
The following are examples contemplated as acceptors and donors for 
intermolecular charge transfer salts. This list is exemplary only and not 
limiting. 
Donors: 
N,N'-Dialkyl 4,4'-bipyridine compounds 
N,N'-Dialkyl 2,2'-bipyridine compounds 
N,N'-Dialkyl 1,10-Phenanthroline compounds 
N,N'-Dialkyl 3,8-Phenanthroline compounds 
O,O'-4,4'-dipyryline compounds 
Phthalocyanine metal complexes 
N-Alkyl pyridine compounds. 
Acceptors: 
N,N'-Dialkyl or diaryl pyromellitimides 
N,N'-Dialkyl or diaryl 1,4,5,8-naphthalenetetracarboxylic diimides 
N,N'-Dialkyl or diaryl 3,4,9,10-perylenetetracarboxylic diimides 
N,N'-Dialkyl or diaryl 3,3',4,4'-biphenyl tetracarboxylic diimides 
N,N'-Dialkyl or diaryl 3,3'4,4'-benzophenonetetracarboxylic diimide 
Any of the above with cyano, bromo, chloro or fluoro substituents on one or 
more of the aromtic rings. 
The following compounds are examples contemplated as intramolecular charge 
transfer salts. This list is exemplary only and not limiting X.sup.- and 
Y.sup.- represent any anion. R is preferabyl an alkyl group. 
##STR8## 
The following compounds are examples contemplated as polymeric 
intramolecular charge transfer salts. This list is exemplary only and not 
limiting. 
##STR9## 
It is contemplated that the first polymeric version can be achieved by 
hydrogenating 13 in the presence of pyromellitic anhydride, isolating the 
amic acid and then dehydrating the amic acid under standard conditions to 
obtain the imide. It is contemplated that the third polymeric version can 
be achieved by the displacement reaction of pyromellitimide dianion on the 
4-Monobromomethyl-2,2'-bipyridyl. 
Examples of acceptor molecules for intramolecular charge transfer salts are 
selected from the following list which is exemplary only and not limiting: 
radicals of compounds containing a carbonyl group conjugated to a 
substituted and unsubstituted aromatic moiety represented by the following 
structure: 
##STR10## 
Aromatic imide compounds and benzoyl compounds contain this group. Examples 
of aromatic imide compounds are polyimides and modified polyimides and 
terephthalates. The Encyclopedia of Chemical Technology Third Edition 
article entitled, "Polyimides", Vol. 18, p. 704-719, the teaching of which 
is incorporated by reference, describes various polyimide materials 
including homopolymers. 
Examples of acceptor moieties for intramolecular charge transfer salts are 
selected from radicals of substituted and unsubstituted forms of the 
following list of neutral compounds which is exemplary only and not 
limiting: unsaturated aromatic hydrocarbons, aromatic carbonyl compound, 
imides, diimides, carbodiimides, anhydrides, quinones, quarternary 
aromatic nitrogen compounds, azomethanes, immonium salts, azo compounds, 
amine oxides, nitro and nitroso compounds, organometallic compounds, 
quinolines and quinoxalines. 
Examples of donor moieties for intramolecular charge transfer salts are 
selected from the violene compounds which are described in the Hunig 
articles incorporated by reference herein above. 
It is contemplated that the intermolecular and intramolecular charge 
transfer salts described herein can be crystallized according to the 
electrocyrstallization technique described by Bechgard et al. in J. Am. 
Chem. Soc., 103, 2440, the teaching of which is incorporated herein by 
reference, and by the crystallization techniques described in Guide For 
The Organic Experimentalist, H. Loewenthal, Pub. Haden (in particular at 
p. 97) the teaching of which is incorporated herein by reference. 
Reduction of compound 16 using the fully reduced viologen, following 
addition of a nonsolvent to grow crystals will produce the state that the 
molecule is contemplated to show conductivity. It is contemplated that 
polymerization is achievable by well established methods, described 
herein, C. E. Sroog, J. Polymer Sci.: Macromolecular Reviews, Vol. 11, pp. 
161-208 (1976), the teaching of which is incorporated herein by reference. 
Scheme A and scheme B below are exemplary only and not limiting. 
##STR11## 
PREATION OF INTERMOLECULAR CHARGE TRANSFER SALT 
Using a literature procedure (M. Mohammad, J. Org. Chem. 1987, 52, 
2779-2782.), diethyl viologen diiodide was reduced by stirring in 
acctonitrile over magnesium turnings for 12-24 hours. This reaction and 
all subsequent steps were carried out in a nitrogen glove box. The 
red-orange solution was decanted from the excess magnesium and evaporated. 
The solid residue was dissolved in pure n-heptane (distilled under 
nitrogen from sodium). The heptane solution was passed through an 
ultrafine fritted glass filter to remove magnesium iodide, then 
evaporated. The darkly colored residue was then dissolved in pure 
dimethoxyethane (DME, distilled from sodium under nitrogen). The 
concentration of reduced viologen in the solution was measured by 
coulometry of a 1-ml aliquot in 50 ml of 0.1M tetrabutylammonium 
fluoroborate in dimethylformamide. This concentration was then used to 
calculate an equimolar amount of N,N-dibutylpyromellitimide which was 
weighed and dissolved in the DME solution of reduced viologen. Dilution of 
the homogeneous solution with 3-4 times its volume of n-heptane and 
chilling at -20.degree. C. resulted in precipitation of a fine, purple 
powder. Four point probe measurements of pressed pellets of this powder 
showed conductivities of 10.sup.3 -10.sup.4 S/cm. under argon. 
Conductivity degraded in air. 
Small crystals of this material were obtained by exposing the DME solution 
of the 1:1 viologen/pyromellitimide mixture to n-heptane vapors in a 
closed container. Slow inter-diffusion of the solvents resulted in crystal 
growth at the bottom of the container which originally contained the DME 
solution. According to the teachings of the present invention 
electrochemically color changing films can be formed. For example, a 
violene or cyanine, e.g. a viologen, can be polymerized and disposed onto 
an electrode. A counterion and a monomeric compound having an imide group 
conjugated to an aromatic moiety, e.g. a bis-imide, can be deposited onto 
the film into which it is absorbed to form a color changing film. 
Alternatively, the compound containing a carbonyl group conjugated to an 
aromatic moiety, e.g. a bis-imide, can be polymerized and disposed onto an 
electrode and a violene or cyanine can be disposed onto the polymer into 
which it is absorbed to form an electrochemical color changing film. By 
the methods of the present invention it is contemplated that these films 
can be made electrically conductive. U.S. Pat. No. 4,571,029 to Skotheim 
et al., the teaching of which is incorporated herein by reference, teaches 
an electrochemical color change cell having a conducting polymer on an 
electrode. The conducting polymer contains color changing pigments which 
change color when the voltage is changed between the display electrode and 
the counter electrode. Polymers and other electroactive materials with 
redox sites are capable of electrical conduction when swelled with an 
eletrolyte as described in copending patent application Ser. No. 
07/290,486 filed Dec. 23, 1988, entitled "Method For Conditioning An 
Organic Polymeric Material" which is assigned to the assignee of the 
present invention, the teaching of which is incorporated herein by 
reference and as described in copending U.S. patent application Ser. No. 
07/411,952 filed on Sep. 25, 1989 entitled "Multilayered Structures Of 
Different Electroactive Materials and Methods Of Fabrication Thereof" 
which is assigned to the assignee of the present invention. 
It is to be understood that the above described embodiments are simply 
illustrative of the principles of the invention. Various other 
modifications and changes may be devised by those of skill in the art 
which will embody the principles of the invention and fall within the 
spirit and scope thereof.