This invention relates to a multimetallic oligomeric or polymeric colorant wherein said colorant is derived from the polymerization of a metal cation with a dimeric tridentate ligand containing a coordinating azo group.

FIELD OF THE INVENTION

This invention relates to a new class of polymeric, multimetallic complex azo colorants. These colorants could find applications in electrophotography, displays, plastics, coatings, recording media, nanotechnology, or as colorants for inkjet inks.

BACKGROUND OF THE INVENTION

Metallic complexes of various azo dyes may be divided into two classes: those in which the azo group doesn't participate in the complexation, and those in which the azo group is one of the coordination sites. These latter complexes have more commercial applications because they exhibit better light stability than similar complexes where the azo nitrogen is not involved in the complexation.

Metal complexes can usually have different ratios between ligands and metal ions, e.g. 1:1, 2:1, and 3:1, etc. Also, depending on the number of coordination sites, ligands can be monodentate, bidentate, tridentate etc. Usually, the more coordination sites in a ligand, the better the chemical stability of the complex. For a comprehensive review on metal complex colorants, including metallized azo dyes and pigments see “Metal Complexes as Specialty Dyes and Pigments” by P. Gregory inComprehensive Coordination Chemistry II-From Biology to NanotechnologyElsevier Ltd., 2003; Chapter 9.12, pp549–579.

If a ligand can form a 2 (or higher):1 (ligand:metal ratio) complex and if two or more ligand molecules are covalently bound such that an intramolecular complexation is not possible, upon metallation, this ligand could potentially form a multimetallic polymeric structure. These multimetallic polymeric azo colorants may have a wide range of molecular weights, potentially controlled by a variety of conditions: e.g. solubility in the polymerization/metallation reaction mixture, the amounts of monomeric ligands added. during metallation, rigidity of the covalent tether in the dimeric ligand, etc. Multimetallic polymeric azo dyes were reported previously by Banerjie et al (Vishwanath Banerjie, Arun K. Dey Makromol.Chem., Rapid Commun.1, 41–46 (1980)) but the ligands described are bidentate (5,5′-(p-phenylenebisazo)diquinolin-8-ol) and the azo group is not a coordination site. The participation of the azo group as a coordination site is critical to the light stability and chemical (or thermal) stability of the dye.

There is still a need for a new class of multimetallic polymeric azo colorants which exhibit light and thermal stability. Such dyes have potential applications either as pigments or dyes in electrophotography, displays, plastics, coatings, recording media, nanotechnology, or inkjet inks.

SUMMARY OF THE INVENTION

This invention provides a multimetallic oligomeric or polymeric colorant wherein said colorant is derived from the polymerization of a polyvalent metal cation with a dimeric tridentate ligand containing a coordinating azo group. In one embodiment the colorant is represented by formulae 1a, 2a, 3a, 1b, 2b, or 3b:

wherein A, A′, B and B′ independently comprise sites capable of forming a coordinate bond with a polyvalent metal ion, wherein said site is 2, 3 or 4 bonds away from the azo group;

L is an unconjugated linking group chosen such that the colorants with formula A-N═N—B-L-B—N═N-A, B—N═N-A-L-A-N═N—B or A-N═N—B-L-A-N═N—B cannot form an intramolecular monomeric complex with the metal ion M;

M is a polyvalent transition metal ion; and

n represents an integer from 0 to 2000.

This invention provides multimetallic polymeric azo colorants which are useful in applications where higher molecular weight has a positive impact on the physical properties of the dye such as the stability to light and atmospheric gases, resistance to solvents, thermal stability, and migration resistance.

DETAILED DESCRIPTION OF THE INVENTION

The dyes of the invention are multimetallic oligomeric or polymeric colorants wherein said colorant is derived from the polymerization reaction of a polyvalent metal cation with a dimeric tridentate ligand containing a coordinating azo group. When an azo dye participates as a ligand in a 2:1 complex with a transition metal cation and if two ligand molecules are covalently bound such that an intramolecular complexation is not possible, they can, upon metallation, form a multimetallic polymeric azo structure.

In a preferred embodiment of the invention, the colorants employed in the invention may be represented by the following general structures:

wherein A, A′, B and B′ independently comprise sites capable of forming a coordinate bond with a polyvalent metal ion, wherein the site is 2, 3 or 4 bond away from the azo group; L is independently an unconjugated linking group chosen such that the colorants with formula A-N═N—B-L-B—N═N-A, B—N═N-A-L-A-N═N—B or A-N═N—B-L-A-N═N—B cannot form an intramolecular monomeric complex with the metal ion; M is a polyvalent transition metal ion; and n represents an integer from 0 to 2000.

A, A′, B or B′ may be independently represented by structure I or structure II:

wherein *denotes the bond to the azo group; X is a heteroatom or group of atoms containing a heteroatom capable of forming a coordinate bond with a polyvalent transition metal ion; Z1is independently H, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted hetaryl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryloxy group, an amino group, a substituted or unsubstituted alkyl or dialkylamino group or a substituted or unsubstituted aryl or diarylamino group; Z2is independently the same as Z1, a cyano or a nitro group, a substituted or unsubstituted alkyl or arylsulfonyl group, a substituted or unsubstituted alkoxy or aryloxycarbonyl group, a substituted or unsubstituted alkyl, dialkyl, aryl, diaryl or aralkylcarbamoyl group, a substituted or unsubstituted alkyl, dialkyl, aryl, diaryl or aralkylsulfamoyl group, a substituted or unsubstituted alkanoyl or substituted or unsubstituted aroyl group; Z1and Z2together may represent the atoms necessary to form a 5- to 7-membered alicyclic, aromatic or heteroaromatic ring; and/or Z1and X may be combined together to form a 5- to 7-membered alicyclic or heteroaromatic ring; and Z contains the atoms necessary to form a substituted or unsubstituted, fused or unfused heterocyclic ring;

In another embodiment, structure I is represented by the following formulae which may be substituted, in addition to the X group, with any other functional group that does not interfere with the action of the colorant:

wherein X may be a hydroxy, carboxy, amino, or imino group, an alkyl- or arylsulfonyl group, an alkyl- or arylsulfonamido group, a sulfamoyl group, an N-aryl- or N-alkylsulfamoyl group, an alkoxy- or aryloxycarbonyl group, an alkyl- or arylcarbonyl group, a sulfo group, or an aryloxy or alkoxy group. R is a substituted or unsubstituted aryl or alkyl group;

In another embodiment of the invention, structure I is represented by the following formulae:

wherein * denotes the bond to the azo group; Y is a hydroxy, carboxy, alkyl- or arylsulfonamide group; and R is a substituted or unsubstituted aryl or alkyl group.

In another embodiment, structure II is represented by the following formulae, which may be substituted with any other functional group that does not interfere with the action of the colorant:

Preferable formulae for structure II are:

In a preferred embodiment of the invention, the multimetallic polymeric azo colorants have formulae 1a, 2a, 3a, 1b, 2b, or 2c wherein any one of A, A′, B or B′ is independently represented by any of the aforementioned formulae for structures I and II. Preferably A and A′ are of Type I and B and B′ are of Type I or Type II, and more preferably B and B′ are Type II. n represents and integer from 0 to 2000, preferably from 0 to 1000, and more preferably 0 to 200.

L is independently an unconjugated linking group chosen such that the colorants with formula A-N═N—B-L-B—N═N-A, B—N═N-A-L-A-N═N—B or A-N═N—B-L-A-N═N—B cannot form an intramolecular complex with the metal ion M. Preferred examples of L are alkylene groups which may or may not contain one or more heteroatoms in the chain, —O-L′-O—, —NH-L′-NH—, —CONH-L′-NHCO—, —COO-L′-OCO—, —OCO-L′-COO—, —SO2NH-L′-NHSO2—, NHCO-L′-CONH—, —NHSO2-L′-SO2NH—, —S-L′-S—, —SO2-L′-SO2—, where L′ is substituted or unsubstituted alkylene, arylene or heteroarylene linking group. Particularly suitable L groups may include —CH2—NH-L′-NH—CH2—, —CONH-L′-NHCO—, —NH-L′-NH—, and, —O-L′-O— groups (wherein L′ is substituted or unsubstituted alkylene, arylene or heteroarylene linking group.)

M is a polyvalent transition metal ion. Preferred examples of M are Cr, Ni, Co or Cu, more preferably M is Ni or Cr, and most preferably M is Ni.

Below are examples of colorants of the invention. The colorants in the present invention include but are not limited to these examples. The colorants are shown in the azo tautomeric form, but any example may exist as either the hydrazone tautomeric form or a mixture of hydrazone and azo forms. The colorants are shown with acidic groups in protonated form but any ionized form associated with a positive counterion of any type may be included:

If desired, the substituents may themselves be further substituted one or more times with the described substituent groups. The particular substituents used may be selected by those skilled in the art to attain the desired colorant properties for a specific application and can include, for example, hydrophobic groups, solubilizing groups, blocking groups, releasing or releasable groups, etc.

In the above dye descriptions, examples of an alkyl group include methyl, ethyl, isopropyl, hydroxyethyl, 3-sulfopropyl and m-carboxybenzyl. Examples of an aryl group include phenyl, naphthyl, 3,5-biscarboxyphenyl and 4-sulfophenyl. Examples of a heteroaryl group include pyridyl, imidazolyl and quinolyl. Examples of halogen include chloro, fluoro, bromo and iodo. Examples of an acyl group include acetyl and 4-sulfobenzoyl. Examples of an alkoxy group include methoxy, 3-carboxypropoxy and 2-hydroxyethoxy. Examples of an aryloxy group include phenoxy, 3-carboxyphenoxy and 4-sulfophenoxy. Examples of an alkoxy- or aryloxy-carbonyl group of 1–10 carbon atoms include methoxycarbonyl, ethoxycarbonyl, 2-methoxyethoxycarbonyl and 3-sulfophenoxycarbonyl. Examples of an alkyl- aralkyl-, aryl-, diaryl-or dialkyl carbamoyl group include N-methylcarbamoyl, N-methyl-N-4-sulfophenylcarbamoyl, N,N-bis (4-carboxyphenyl)carbamoyl. Examples of an alkyl- aralkyl-, aryl-, diaryl-or dialkyl sulfamoyl group include N-methylsulfamoyl, N-methyl-N-phenyl-sulfamoyl, N-(p-sulfophenyl)sulfamoyl and N,N-bis (4-carboxyphenyl)sulfamoyl. Examples of an acylamino group include acetamido, methoxyethylacetamido and 3-carboxybenzamido. Examples of a ureido group include N-methylureido, ureido and N,N′-dimethylureido. Examples of a sulfonylamino group include methanesulfonamido, p-toluenesulfonamido and 2-sulfatoethanesulfonamido. Examples of an alkyl- aralkyl-, aryl- diaryl- or dialkylamino group include methylamino, N,N-dimethylamino, methoxyethylamino and 3-sulfoanilino.

EXAMPLES

In general the polymeric multimetallic colorants of the invention are synthesized as follows. Ligands A-N═N—B-L-B—N═N-A, B—N═N-A-L-A-N═N—B or A-N═N—B-L-A-N═N—B are synthesized using appropriate chemical transformations depending on their specific structure. Stoichiometric amounts of ligand A-N═N—B-L-B—N═N-A or B—N═N-A-L-A-N═N—B or A-N═N—B-L-A-N═N—B, an aqueous solution of a Ni, Cr, Co or Cu salt and optionally monomeric ligand A′-N═N—B′ are mixed in dimethylformamide and heated at 85° C. for 4 hours. The polymeric colorant is isolated through precipitation by addition of a suitable non-solvent.

Synthesis of the Dimeric Unmetallized Colorant 13

Synthesis of the Dimeric Unmetallized Colorant 15

Dimer 14 (0.8 g) was suspended in 50 mL water and cooled in ice bath. To this suspension was added drop wise a solution of 2.74 g cerium ammonium nitrate (CAN) in 10 mL water. The reaction mixture was stirred 45 min in ice bath and a solution of 0.455 g pyridyl hydrazine dihydrochloride in 5 mL water was added drop wise. The ice bath was removed and the reaction mixture stirred for 16 hours at ambient temperature. 100 mL acetone was added in order to precipitate the product and the resulting red precipitate was filtered and washed with 2×10 mL acetone. Yield 0.8 g 15 (86% of theoretical).

Synthesis of the Dimeric Unmetallized Colorant 18

3-Aminomethyl-2methyl-5,8-dimethoxyquinoline (1.16 g) and 0.84 g NaHCO3were dissolved in 25 mL water+25 mL acetonitrile and the resulting solution was cooled in ice bath. Added 0.46 g cyanuric chloride dissolved in 25 mL acetone was added, the solution was removed from the ice bath and stirred at 25° C. for 2.5 hours. Approx 100 mL water were added and a fluffy off white precipitate formed. Filtered, washed and dried to obtain 1.4 g of 16 (97% yield).

0.58 g quinoline dimer 16 was suspended in 20 mL ethanol and cooled in ice bath. A solution of 1.64 g ammonium cerium nitrate in 10 mL of water was added dropwise and stirred 1.5 hours. Then a solution of 0.8 g pyridyl hydrazine dihydrochloride in 5 ml of water was added and the ice bath removed. After stirring for another 1.5 hours, the ethanol was evaporated with a rotary evaporator and 30 mL of water were added. The orange product 17 precipitated and was isolated by filtration (0.6 g, 86% yield).

To a solution of 0.35 g chlorotriazine dimer 16 in 30 ml N-methylpyrrolidone (NMP) was added a solution of 0.07 g of taurine and 0.27 g sodium carbonate in 15 mL of water and the resulting mixture was heated at 100° C. for 4 h. The product was precipitated by addition of 200 mL water and subsequent adjustment of the pH to 5. The precipitate was filtered, washed with 2×5 mL ice water and dried in the vacuum oven to afford 0.315 g dimer 18 (80% yield).

0.84 g dimer 13 and 67 mg monomer 19 were suspended/dissolved in 50 mL DMF. The mole ratio of dimer/monomer is 5:1. To this mixture were added 297 mg Ni(OAc)2.4H2O. The mixture was heated at 85° C. for 4 hours. HPLC shows multiple peaks of polymeric species with generic structure 12. The bulk of the solvent was evaporated, 100 mL water was added and the precipitate that formed was collected. by filtration (yield 0.95 g).

A solution of 77 mg of dimer 13 and 25 mg Ni(OAc)2.4H2O in 5 mL DMF and 3 mL water was heated at 85° C. for 18 hours. The solvent was evaporated with a high-vacuum centrifuge and the polymeric multimetallic colorant obtained was analyzed by size-exclusion chromatography (SEC). SEC results:

Absolute Molecular Weight Averages:

A suspension of 70 mg dimer 17 and 25 mg Ni(OAc)2.4H2O) in 5 ml DMF and 2 mL water were heated at 85° C. for 16 h. The resulting polymer was analized by Matrix Assisted Laser Desorption Ionization (MALDI). MALDI results indicate the presence of species with general formula LmNimwhere L is ligand 17 and m is an integer between 2–17. This data confirms the presence of cyclic oligomeric/polymeric species with general structure 2b.