GB2372750A

GB2372750A - Water soluble hexa co-ordinated metal complexes of monoazo dyes for use in inks suitable for ink jet printing

Info

Publication number: GB2372750A
Application number: GB0200763A
Authority: GB
Inventors: Maria Soteri Hadjisoteriou; Rachel Anne James
Original assignee: Avecia Ltd
Current assignee: Avecia Ltd
Priority date: 2001-01-18
Filing date: 2002-01-15
Publication date: 2002-09-04
Anticipated expiration: 2022-01-15
Also published as: GB0200763D0; US20020130937A1; GB2372750B; US6712890B2

Abstract

A water soluble compound of Formula (1) or a salt thereof:- <EMI ID=1.1 HE=36 WI=30 LX=948 LY=406 TI=CF> <PC>[wherein:- Y is an electron withdrawing group; Y<SP>1</SP> is H, alkyl or aryl, OR or NR<SB>2</SB> in which each R independently is H, optionally substituted alkyl or optionally substituted aryl; or Y and Y<SP>1</SP> together form a 5- or 6- membered ring; X<SP>1</SP> is a group or atom with co-ordinates with M; M is hexa co-ordinate metal; G is a group of Formula (2), (3) or (4); and L<SP>1</SP>, L<SP>2</SP> and L<SP>3</SP>, each independently represent ligands required to complete hexa-coordinate geometry around metal M; <EMI ID=1.2 HE=60 WI=28 LX=894 LY=1236 TI=CF> <EMI ID=1.3 HE=32 WI=26 LX=1006 LY=1971 TI=CF> <PC>wherein: S is a water solubilizing group; Ar is a benzene or naphthalene group in which X is located ortho to the azo group; X is a group or atom which co-ordinates with M; Z provides atoms or groups which complete; Ring B which is an optionally substituted 5- or 6-membered aromatic heterocyclic ring; Ring A is an optionally substituted aromatic ring; n is 0, 1, 2 or 3; and the * signify the points of attachment of the groups of Formulae (2), (3) and (4) to the N and M atoms in the compound of Formula (1)] may be combined with an aqueous liquid medium to provide a liquid ink composition which is suitable for ink jet printing.

Description

(57) cant Sn I X. Formula (2) C. _ Formula (3) it* ( B N *

Fonnula (4) wherein: S is a water solubilizing group; Ar is a benzene or naphthalene group in which X is located ortho to the azo group; X is a group or atom which co-ordinates with M; Z provides atoms or groups which complete; Ring B which is an optionally substituted 5- or 6-membered aromatic heterocyclic ring; Ring A is an optionally substituted aromatic ring; n isO, 1,20r3; and the * signify the points of attachment of the groups of Formulae (2), (3) and (4) to the N and M atoms in the compound of Formula t1)] may be combined with an aqueous liquid medium to provide a liquid ink composition which is suitable for ink jet printing.

K\ ' COMPOSITIONS

The present invention relates to water soluble compounds and their salts, to compositions containing such compounds and their use in ink jet printing ("IJP"), to ink jet 5 printer cartridges and to ink jet printing processes.

IJP is a non-impact printing technique in which droplets of coloured liquids are ejected through a fine nozle onto a substrate without bringing the nozle into contact with the substrate.

IJP is a relatively inexpensive way of recording multicolour images, for example 10 pictures obtained from digital sources such as electronic cameras, scanners and the Internet. The use of ink jet printers to print colour images in the home or office environment is now becoming commonplace. However IJP has a big disadvantage compared to conventional silver halide photography in that the resultant images fade in ordinary daylight. Thus, there is a need to improve the light-fastness properties of prints 15 to prevent images fading or vanishing, or becoming discoloured over time. In addition, there are many demanding performance requirements for dyes and inks used in IJP. For example sharp, nonfeathered images having good water-fastness and optical density are required. The inks are required to dry quickly when applied to a substrate to prevent smudging, but they should not form a crust over the tip of an ink jet nozle which stops 2 0 the printer from working effectively. The inks should also be stable to storage over time without decomposing by forming a precipitate which could block the fine nozle.

The choice of a colorant in ink jet systems is critical to image quality. The colorants should also have a high degree of light-fastness after printing onto a substrate.

For aqueous dye-based inks, the dyes need to be sufficiently soluble in water to prepare 25 a solution that is capable of producing adequate density on the substrate and be stable for extended periods of storage without precipitation. It is difficult to find dyes which meet all of these requirements, particularly yellow dyes.

US patents 4,393,132, 4,183,755 and 4,148,643 disclose the formation of metal chelating compounds in the course of a reaction during photographic development 30 followed by diffusion into a photographic image receiving layer in which the metallised dye is formed and immobilised. These patents do not specify the use of premetallised dyes and only refer to the formation of metal complexes on diffusion of the dye into the image receiving layer.

European patent 260,561 describes the use of related compounds for dyeing 3 5 leather.

German OLS 2404314 describes certain formulations of Cr and Co coordinated dyes which would not be suitable as ink jet inks.

Water immiscible yellow dyes are described in US patents 4,407,931 and 4, 418,131 and are useful in photographic applications.

<-- According to the present invention there is provided a water soluble compound of Formula (1) or a salt thereof: y <CONS '\' Y

L''1 \L3

Formula (1) 5 wherein: Y is an electron withdrawing group; Y' is H,alkyl or aryl, OR or NR2 in which each R independently is H. optionally substituted alkyl or optionally substituted aryl; or Y and Y' together form a 5- or 6- membered ring; 10 X' is a group or atom which coordinates with M; M is hexa co-ordinate metal; G is a group of Formula (2) , (3) or (4); and L', L2 and L3, each independently represent ligands required to complete hexa coordinate geometry around metal M; S. Ar* X* Formula (2) Sac* Z N* Formula (3) i* (IN * Z Formula (4)

r - ) wherein: S is a water solubilizing group; Ar is a benzene or naphthalene group in which X is located ortho to the azo group; X is a group or atom which co-ordinates with M; 5 Z provides atoms or groups which complete an optionally substituted 5- or 6 membered aromatic heterocyclic ring; Ring A is an optionally substituted aromatic ring; Ring B is an optionally substituted 5- or 6-membered aromatic heterocyclic ring; nisO, 1,20r3; 10 and the * signify the points of attachment of the groups of Formulae (2), (3) and (4) to the N and M atoms in the compound of Formula (1).

The compounds of Formula (1) preferably comprise at least one water solubilising group which is preferably a carboxy, amide, sulpho, sulphonamide or phosphate group which is preferably present in Y or Y', or is a substituent on Ring B or on Ring A 15 preferably in a position pare with respect to the azo group.

Y is preferably selected from ON, CO2H, CO2R, CONR2, COR and -SO2NR2 in which each R is independently defined as above.

Where Y. is alkyl it is preferably C 8-alkyl, more preferably C,4-alkyl.

Where Y' is aryl it is preferably phenyl.

20 Where R is optionally substituted alkyl it is preferably C'.8-alkyl, more preferably C,.4-alkyl. Where R is optionally substituted aryl it is preferably phenyl or naphthyl, more preferably phenyl.

Where R is optionally substituted alkyl or aryl optional substitutents are preferably 25 selected from water solubilising groups, particularly S03H, SO2NR2, CO2H or PO3H2.

Where Y and Y' are joined together to form a 5- or 6-membered ring it is preferably pyrazolone or triazole, more preferably pyrazolone or 1, 3, 4 triazole.

X and X' each independently is preferably 0, CO2R or NR in which R is defined above. Where X or X' is CO2R co-ordination to the metal occurs through an O atom and 3 o the C atom to which it is attached is included to form a 6 -membered ring.

M is preferably Zn2+, Cu2+, Co2+ Co3+ Pt2+ Pd2+ Cr3+ or Ni2+ Optional substitutents for Rings A and B are preferably selected from C'4-alkyl, aryl, SO3H, SO2NR2, CO2H or PO3H2 in which R is as defined above.

in a first preferred embodiment of the present invention in the compound of 35 Formula (1) G is a group of Formula (2), this is shown below as the compound of Formula (5)

y X ME L'' I L3

L2 Formula (5) in which Y. Y4, X, X', M, Ar, L', L2, L3, S and n are as defined above.

In a second preferred embodiment of the present invention in the compound of Formula (1) G is a group of Formula (3), this is shown below in the compound of Formula (6).

y z N L' L2 L3

Formula (6) in which Y. Y', X', M, L', L2, L3, Z. S. Ring B and n are as defined above.

In a third preferred embodiment of the present invention in the compound of Formula (1) G is a group of Formula (4), this is shown below as the compound of Formula 1 0 (7);

y N (:L1 /L2'L3 X

Formula (7) in which Y. Y', X', M, L', L2, L3, Z and Rings A and B are as defined above.

15 In a further preferred embodiment of the present invention in the compound of Formula (1) G is a group of Formula (4): Z preferably comprises a chain of two or three carbon atoms or one or two carbon atoms and one nitrogen atom, more preferably Z is of formula -CR2=CR2-CR2= wherein each R2 is independently H or a substituent, of which one may be a

- hydrophilic group for example a carboxy, amide, sulpho, sulphonamide or I phosphate group in order to increase the water Volubility of the compound; it is preferred that any non hydrophilic substituent is H. It is especially preferred that X forms part of a quinoline group; 5 X' is preferably O or NR3 wherein R3 is H or optionally substituted alkyl.

Y is preferably ON, CoNR4R5, S02NR4R5, CoR4 or C02R4 wherein R4 and Rs are each independently H or C'--alkyl groups which may be substituted by water solubilising groups preferably carboxy, amide, sulpho, sulphonamide or phosphate groups; 10 or R4 and Rs together with the nitrogen atom to which they are attached form a 5- or 6-membered ring; M is preferably Zn2+ , Cu2+, Co2+, Co3+, Pt2+, Pd2+, Cr3+ or Ni2+, more preferably Ni2+; and L', L2 and L3 represent three monodentate ligands, one bidentate ligand and one 15 monodentate ligand or one tridentate ligand.

Monodentate ligands include cosolvents for the compound, for example lower alcohols (for example C, ff-alkylOH, preferably C,4-alkylOH), tetrahydrofuran or ammonia.

The ligands L', L2 and L3 may be 3 separate independently selected monodentate ligands, or a monodentate ligand and a bidentate ligand or preferably a tridentate ligand; 20 preferred tridentate ligands represented by L', L2 and L3 collectively are ligands of either Formula (8), Formula (9) or Formula (10) where Y. Y', X, X', Z. Ar, S. n and Rings A and B are as defined above and which incorporate water- solubilizing groups as mentioned above. YY ENS. J-ry1Sit X, Formula (8) Formula (9) In a particularly preferred embodiment the compounds of Formulae (5) and (6) are symmetrical 2: 1 complexes of Formulae (11) and (12) wherein each Ar, X, X', Y. Y', Z. S. n, Ring B and M are as hereinbefore defined.

- - $ AreWN n YY Formula (11)Formula (12) M in Formula (5) is preferably Zn2+, Cu2+, or Ni2+, more preferably Ni2+ and M in Formula (6) is preferably Zn2+, Cu2+, Co2+, Co3+, Cr3+or Ni2+, more preferably Nib.

5 A preferred tridentate ligand represented by L', L2 and L3 collectively is a ligand of Formula (10) in which Y. Y', X', Z. and Rings A and B are as defined above and which possesses water-solubilising groups as specified for R above: N=N N X'

Formula (10) 10 A particularly preferred embodiment the compound of Formula (1) is of Formula (13): 7 Y Z:N M X

IN =N Formula (13) in which each X4, Y. Y', Z. M and Rings A and B are each independently as defined above. 15 In compounds of Formula (13) the preferences for X', Y. Y', Z. M and Rings A and B are as hereinbefore defined for the compounds of Formula (1).

The above compounds are preferably yellow dyes.

According to a further feature of the present invention there is provided a liquid ink composition suitable for ink jet printing which comprises an aqueous liquid medium 20 and, dissolved therein, one or more compound(s) of Formulae (1), (5), (6), (7), (11), (12) and (13).

A preferred composition comprises:

(a) from 0.01 to 30 parts of a compound of the Formula (1), more preferably of Formula (3); and (b) from 70 to 99.99 parts of the liquid medium; wherein all parts are by weight and the number of parts of (a)+(b) =100.

5 Preferred liquid media include water or a mixture of water and one or more organic solvents.

When the liquid medium comprises a mixture of water and organic solvent, the weight ratio of water to organic solvent is preferably from 99:1 to 1:99, more preferably from 99:1 to 50:50 and especially from 95:5 to 80:20.

10 It is preferred that any organic solvent present in the mixture of water and organic solvent is water-miscible. Preferred water-miscible organic solvents include C,6-alkanols, preferably methanol, ethanol, npropanol, isopropanol, n-butanol, sec-butanol, tert-butanol, n-pentanol, cyclopentanol and cyclohexanol; linear amides, preferably dimethylformamide or dimethylacetamide; ketones and ketone-alcohols, preferably acetone, methyl ether ketone, 1 5 cyclohexanone and diacetone alcohol; water-miscible ethers, preferably tetrahydrofuran and dioxane; dials, preferably dials having from 2 to 12 carbon atoms, for example pentane-1,5 diol, ethylene glycol, propylene glycol, butylene glycol, pentylene glycol, hexylene glycol and thiodiglycoi and oligo- and polyalkyleneglycols, preferably diethylene glycol, triethylene glycol, polyethylene glycol and polypropylene glycol; trials, preferably glycerol and 20 1,2,6-hexanetriol; mono-C,4-alkyl ethers of dials, preferably monoC,4-alkyl ethers of diols having 2 to 12 carbon atoms, especially 2methoxyethanol, 2-(2-methoxyethoxy)ethanol, 2-(2-ethoxyethoxy)-ethanol, 2[2-(2-methoxyethoxy)ethoxy]ethanol, 2- 2-(2-ethoxyethoxy) ethoxy]-ethanol and ethyleneglycol monoallylether; cyclic amides, preferably 2pyrrolidone, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, caprolactam and 1,3-dimethylimidazolidone; 25 cyclic esters, preferably caprolactone; sulphoxides, preferably dimethyl sulphoxide and sulpholane. Preferably the liquid medium comprises water and 2 or more, especially from 2 to 8, water-soluble organic solvents.

Especially preferred water-miscible organic solvents are cyclic amides, especially 2 pyrrolidone, N-methyl-pyrrolidone and N-ethyl-pyrrolidone; diois, especially 1,5-pentane diol, 30 ethyleneglycol, thiodiglycol, diethyleneglycol and triethyleneglycol; and mono- C,4-alkyi and C,4-alkyl ethers of dials, more preferably mono- C,4-alkyl ethers of dials having 2 to 12 carbon atoms, especially 2-methoxy-2-ethoxy-2-ethoxyethanol.

Examples of further suitable ink media comprising a mixture of water and one or more organic solvents are described in US 4,963,189, US 4,703,113, US 4,626,284 and EP 35 4,251,50A.

The solvent preferably has a boiling point of from 30 to 200 C, more preferably of from 40 to 150 C, especially from 50 to 125 C.

The liquid medium may also contain additional components conventionally used in ink jet printing inks, for example viscosity and surface tension modifiers, corrosion

inhibitors, biocides (e.g. Proxel from Avecia Ltd), humectants, kogation reducing additives and surfactants which may be ionic or non-ionic.

Surfactants may be included in the liquid medium to adjust the surface tension of the compositions to an appropriate level. The surfactants are preferably anionic, cationic, 5 amphoteric or nonionic.

Preferably the composition has been filtered through a filter having a mean pore size below 10pm, more preferably below Gem, especially below Am, more especially below 1 m. In this way particulate matter is removed which could otherwise block the fine nozzles used in ink jet printers.

10 Preferably the composition has a viscosity of below 20cp, more preferably below 1 Ocp, especially below Sop, at 20 C.

Preferably the compounds described herein have been purified by reverse osmosis, ultra-filtration, ion exchange or a combination thereof, either before or after they are incorporated in a liquid ink composition according to the present invention.

15 Preferably the liquid composition is yellow.

A further feature of the present invention provides a process for printing an image on a substrate comprising applying thereto by means of an ink jet printer a liquid ink composition which comprises an aqueous medium and dissolved therein one or more compounds of formulae (1), (5), (6), (7), (11), (12), and (13).

2 0 The ink jet printer preferably applies the composition to the substrate in the form of droplets which are ejected through a small orifice onto the substrate. Preferred ink jet printers are piezoelectric ink jet printers and thermal ink jet printers. in thermal ink jet printers, programmed pulses of heat are applied to the composition in a reservoir by means of a resistor adjacent to the orifice, thereby causing the composition to be ejected in the 25 form of small droplets directed towards the substrate during relative movement between the substrate and the orifice. In piezoelectric ink jet printers the oscillation of a small crystal causes ejection of the composition from the orifice.

A further feature of the invention provides an ink jet printer cartridge, optionally refillable, containing a liquid ink composition which comprises an aqueous medium and 30 dissolved therein one or more compounds of formulae (1), (5), (6), (7), (11), (12), and (13).

The substrate is preferably paper, plastic, a textile, metal or glass, more preferably paper, an overhead projector slide or a textile material, especially paper.

Preferred papers are plain or treated papers which may have an acid, alkaline or neutral character.

35 A further aspect of the present invention provides separately a paper, an overhead projector slide and a textile material printed with a liquid ink composition according to the present invention or by means of a process as defined above.

When the substrate is a textile material the liquid ink composition of the present invention is preferably applied thereto by:

i) applying the ink to the textile material using an ink jet printer; and ii) heating the printed textile material at a temperature of from 50 C to 250 C.

Preferred textile materials are natural, synthetic and semi-synthetic materials.

Examples of preferred natural textile materials include wool, silk, hair and cellulosic 5 materials, particularly cotton, jute, hemp, flax and linen. Examples of preferred synthetic and semi-synthetic materials include polyamides, polyesters, polyacrylonitriles and polyurethanes. Preferably the textile material has been treated with an aqueous pretreatment composition comprising a thickening agent and optionally a water-soluble base and a 10 hydrotropic agent and dried prior to step i) above.

The pre-treatment composition preferably comprises a solution of the base and the hydrotropic agent in water containing the thickening agent. Particularly preferred pre treatment compositions are described more fully in European Patent Application No.534660. 15 The invention also provides a process of ink jet printing in which droplets of a liquid ink composition according to the invention are deposited on a suitable substrate.

The invention is further illustrated by the following Examples in which all parts and percentages are by weight unless otherwise stated.

2 0 EXAMPLES

The following procedures provide examples for preparation of dyes of general Formula 1. A range of dyes can be made by variations in the coupling component and aromatic amine.

Example 1 (Dye 1 and Dye 2) 25 1. Preparation of 8-amino-5-quinoline sulohonic acid (I) SO3H (1)

NH2 A solution of 8-hydroxy-5-quinoline sulfonic acid (0.2mol, 45g) and sodium bisulfite 30 (0.4mol, 41.6g) in water (200mL) and aqueous ammonia solution (35%) (100mL) was heated to reflux for 3 days, the initial slurry dissolved to form a clear orange solution. This solution was cooled to room temperature and acidified to pH 2 by the careful addition of concentrated HCI. A yellow solid was precipitated and isolated by filtration. The reversible nature of this reaction means that the product obtained at this stage is a 35 mixture of the desired amino-quinoline and the starting hydroxy quinoline. This mixture was then dissolved in pyridine (1 50mL), chilled in an ice bath and acetic anhydride (30mL)

added gradually. The solution was stirred for 1 hour and the N-acylated product precipitated by addition of acetone. This product was isolated by filtration as an off-white solid (approx. 25g) which was suspended in water (30mL) and heated to dissolve.

Concentrated HCI (30mL) was added and the solution heated at reflux for 1 h during which 5 time the amino-quinoline product precipitated. The reaction mixture was cooled to room temperature and the clean product was isolated by filtration as a yellow powder (15g, 33%); m/z (ES-) 223; 1H NMR (D2O)d 8.82 (dd, J = 8.3, 2.2Hz, 1H), 8.69 (dd, J - 4.4, 2.2Hz, 1 H), 7.93 (d, J = 8.0Hz, 1 H), 7.63 (dd, J = 8.8, 4.4Hz, 1 H), 6.96 (d, J = 8. 0Hz, 1 H).

10 2. Preparation of acetoacetamide derived Roland (II) o Em NH2 HO3S N=N (1l) IN HO A stirred solution of 8-amino-5-quinoline sulfonic acid (11.2g, approximate purity 15 60%) in water (150mL) and ethanol (80mL) was chilled in an ice bath and concentrated.

HCI (17mL) added. This was followed by the addition of sodium nitrite ( 2. 76g, 40mmol) and the mixture stirred at 0 C for 1 h a give a diazenium salt solution. Sulphamic acid was added to quench excess nitrous acid using sulphone indicator to show when excess nitrous acid is consumed.

20 Separately a solution of acetoacetamide (4.55g, 45mmol) and sodium carbonate (20g) in water (100mL) was chilled in an ice bath. The solution of diazonium salt was added gradually controlling the pH between pH 8-9 by addition of sodium carbonate and the reaction stirred for 1h. Analysis of the reaction mixture by HPLC indicated complete conversion to the desired product. The reaction mixture was acidified to pH 5 by addition 25 of glacial acetic acid and the solution left to stand for 2 days. The solution was then filtered to provide the product as a yellow solid (5g, yield based on 60% purity of starting material approx. 50%); m/z (ES-) 335; 'Hi NMR (D2O) d 8.61 (dd, J = 8.3, 1.9Hz, 1 H), 8.33 (dd, J = 4.4, 1. 8Hz, 1H), 7.71 (d, J = 8.3Hz, 1H), 7.32 (dd, J = 8.0, 4.3Hz, 1H), 6.95 (d, J = 8.3Hz, 1H), 1.81 (s, 3H).

3. Preparation of nickel complexes of Formula 1 A solution of nickel acetate tetrahydrate (1.49g, 6mmol) in a 50:50 water ethanol mix was added dropwise over 30 minutes to a stirred suspension of acetoacetamide ligand (II) (4.0g, 12mmol) in THE (30mL) and ethanol (30mL) under a nitrogen 3 5 atmosphere. On addition of the nickel salt the ligand dissolved to form a deep yellow/brown solution. HPLC analysis of the reaction mixture on completion of addition of

it-' \ nickel acetate showed the formation of 2 new species in an approximately 2: 1 ratio.

Stirring of the reaction was continued for 2 days after which time both products were still present with no noticeable change in the relative quantities. The solution was concentrated in vacuo and the residue suspended in ethanol and with stirring heated to 5 boiling. On cooling the reaction mixture was filtered to provide an orange-brown solid of limited water solubility which was shown by HPLC to consist mainly of the minor product of (Dye 2) (approx. 90% purity, 1.19). The filtrate was reconcentrated in vacua to provide a reddish crystalline solid which was recrystallized from ethanol to provide the major product (Dye 1) (1.7g). Both products were further purified by dialysis. MS analysis of 10 the complexes shows the minor product to be a 1: 1 nickel complex m/z (FAB-) 392 and the major product to be a 2: 1 complex m/z (FAB-) 727.

o Em NH2 HO3S N=N O NH2

it HO3S N=N IN SO3H 1: 1 Nickel complex H2N - <

o Dye 2 Dye 1 EXAMPLE 2 (Dye 3) CN HO3S >h' NSO H CN Dye 3 Dye 3 was prepared as follows

A Preparation of upland (IV) by coupling of 3-amino-4-hYdroxv benzene sulfonic acid and pivalovl acetonitrile HO3S OH N mu< ( l V) 5 A solution of 3-amino-4-hydroxy benzene sulfonic acid hydrate (50mmol, 9.45g) in water (approx. 200mL) was cooled to 0 C in an ice bath. Concentrated HCI (20mL) was added followed by the addition of sodium nitrite (50mmol, 3. 45g) and the reaction stirred at 0 C for 1 h to give a diazonium salt solution. Excess nitrous acid was then quenched by addition of sulfamic acid.

10 Separately a solution of pivaloyl acetonitrile (55mmol, 6.88g) and sodium carbonate (approx. 50g) in water (150mL) was cooled to 0 C in an ice bath. The diazonium salt solution was gradually added and the pH maintained at >pH8 by addition of sodium carbonate. The reaction mixture was then stirred at 0 C for 1 h after which time HPLC analysis showed only 1 peak corresponding to the product. The reaction was then 15 acidified to pH 5 by addition of concentrated HCI and the product isolated by filtration as a yellow powder; m/z (ES-) 324; 'H NMR (D2O) d 7.83 (s, 1 H), 7.47 (dd, J = 8.6, 2.6Hz, 1 H), 6.88 (d, J = 8.6Hz, 1 H), 1.40 (s, OH).

20 Preparation of Dve 3 A solution of nickel acetate tetrabydrate (3.73g, 15mmol) in a 50:50 water, ethanol mix was added dropwise over 30 minutes to a stirred suspension of the ligand (10.0g, 30.8mmol) in THE (50mL) and ethanol (100mL) under a nitrogen atmosphere. After stirring at room temperature for 2 hours HPLC analysis showed the presence of a new 25 species and no remaining starting material. The reaction mixture was filtered to provide a yellow/brown solid (8.7g) which was purified by dialysis. FAB MS indicated that this product is the 2: 1 nickel complex; (FAB-) 705.

EXAMPLES 3 - 5 (Dyes 4 - 6) 30 Further examples of dyes of general Formula (1) were prepared by the above procedures by variation of the coupling components and aromatic amines.

vc) ' CN HO3S N.N:

\ N SO3H

CN Dye 4 O 'NH2 CN

HO3SO̳H HO3SN NJ SO3H

Dye 5 (1: 1 Nickel complex) Dye 6 (1: 1 Nickel complex) Preparation of water solubilized coupling component (Ref. US 5376513) N-(2-ethane sulfonic acid) cvanoacetamide (111) (for preparation of Dye 5) o NC J] N So3H (111) H 10 A suspension of taurine (25g, 0.2mol) and potassium hydroxide (13.5g, 0.24mol) in methanol (100mL) was heated to reflux. Ethyl cyanoacetate (24.9g, 0.22mol) was added dropwise over the course of 1h. The mixture was refluxed for a further 5h during which time the reaction mixture solidified, allowed to cool and left to stand overnight. The solid product was isolated by filtration and purified by recrystalisation from ethanol to give 15 the acetamide product as a white solid (34.6g, 90%); m/z (ES-) 313; 'H NMR (D2O) d 3.10 (t, J = 6.9Hz, 2H), 3.27 (t, J = 5.8Hz, 1 H), 3.42 (t, J = 5.8Hz, 1 H), 3.60 (t, J = 6.9Hz, 2H).

EXAMPLES OF FORMULA (1) in which G is of Formula (3).

20 These dyes were prepared via means of the diazotisation followed by coupling of the 2-amino-pyridine N-oxide according to the procedure shown above. The N-oxide was cleaved to provide the pyridine ligand for example by treatment with phosphorus bichloride. Metallation to provide the complexes was achieved by treatment with nickel acetate as described above.

Preparation of Pvridine N-oxides (Ref. Deady, L.W; Synth. Commun. 1977, 7(8), 509) To a solution of amino pyridine (50g, 0.53mol) in acetone (9OOmL) a solution of 3 chloro perbenzoic acid (112.2g, 0.65mol) in acetone (300mL) was added and the reaction mixture stirred at room temperature for 30 min. Diethyl ether (500mL) was added and the 5 solution acidified to pH 4 with concentrated HCI. The amino pyridine-N- oxide hydrochloride salt was then isolated by filtration as an off-white powder (629, 80%); m/z (ES+) 111; 'Hi NMR (do DMSO) d 8.14 (dd, J = 6.9, 1.8Hz, 1H), 7.66 (s, 2H, NH2), 7 47 (dt, J = 7.6, 1.5Hz, 1 H), 6.99 (dd, J = 8.1, 1.5Hz, 1H), 6.72 (dt, J = 7.6, 1.8Hz, 1 H).

10 Linand formation reactions 1) For example the ligand for Dye 10 was made via diazotisation of an amino-triazoles as follows: 2-Amino-5carboxy-1,3,4-triazole (6.85g, 50mmol) was dissolved in water (150mL) at pH 8-9 and a 1M solution of sodium nitrite (3.80g, 55mmol) added. This 15 solution was then cooled to 0-5OC and then gradually added (over 20mins) to concentrated HCI (25mL) at 0-5OC to form a diazonium suspension over the approximately 90mins after which time excess nitrous acid was quenched by addition of sulfamic acid. The diazonium suspension was added gradually to a solution of 3-methyl 1-(4-sulfophenyl)-2-pyrazolin-2-one (13.98g, 55mmol) at 0 C in a 50:50 methanol: water 20 mix (300mL). The reaction mixture was stirred for 90min and the pH then raised to pH 5 by addition of sodium carbonate and allowed to warm to room temperature overnight.

The product was isolated by filtration, dialysed and dried to provide the ligand as a yellow solid (19.65g).

All other diazotisation reactions were carried out by a similar method with the 25 exception of those utilising amino-pyrazoles.

2) For example the ligand for Dye 11 was made via diazotisation of an amino-pyrazole as follows: A mixture of acetic acid (15mL) and propionic acid (10mL) were cooled to 0-5OC 30 and nitrosyl sulphuric acid (4.579, 36mmol) added gradually over 10mins. The mixture was stirred for 15mins. A solution of 3-amino-4-carbethoxypyrazole (30mmol, 4.659) in acetic acid (15mL) and propionic acid (10mL) was added dropwise and the diazonium salt allowed to form for a further 45mins. Excess nitrous acid was thenquenched by the addition of sulfamic acid and the diazonium solution added gradually to a solution of N 35 methyl-4-sulfomethyl-pyridone (7. 01g, 32mmol) in water (200ml) at 0-5OC. On completion of the addition the pH was raised to pH34 by addition of 2M NaOH. The reaction mixture was stirred overnight and filtered to obtain the product as a yellow solid which was purified by stirring with acetone and refiltering (Yield = 7.0g) .

I\ - -)

The carbethoxypyrazole was hydrolysed to the carboxypyrazole by heating at 70 C in 2M NaOH for approx 30mins.

Metallisation Prep for Dye 10 To a solution of the ligand (6.00g,16. 75mmol) in water (100mL) at pH8 a solution 5 of nickel acetate (2.23g, 9mmol) in water (50mL) was added dropwise over the course of 15mins. The pH throughout the addition was maintained at pH8 by addition of 2M NaOH.

HPLC analysis of the reaction mixture after 1 h showed the appearance of a new species (?max=465.9nm) as well as residual unreacted ligand. A solution of additional nickel acetate (8mmol) in water was then added and the reaction mixture stirred for a further 1 h 10 after which time HPLC analysis showed complete conversion of the ligand to the new species. The solution was then partially concentrated in vacua and then passed down an IDA (imino-diacetic acid) column (to remove excess free nickel salts). The deep brown solution was then dialysed and dried to provide metal complex Dye 10 (5.65g).

Other metallisation reactions carried out according to a similar procedure to Dye 15 10.

Examples 6 - 10 (Dyes 8 - 12) The following metallised dye structures were prepared by methods described above or analogous methods: HO2C - NH N'N: CO2H

≥ N; N

N=N \N=N H

N N')_oH N Ny-oH | 2: 1 nickel I nickel SO3H complex complex N-N HO2C N NO Dye 10 SO3H SO3H HO IN O

Dye 8 Dye 9 nickelcomplex

r>. SO3H CO2H SO3H \ _ N CO2H

N 2:1 nickel HO N O complex 2: 1 nickel complex SO3H Dye 1 1 Dye 12 5 RESULTS TABLE

Dyes 1 - 6 and 9 -12 and unmetallised Comparative Dye 7 were formulated into inks and applied to a substrate by means of an ink jet printer. The ink formulation used comprised 88% water, 5% 2-pyrrolidone, 5% thiodiglycol and 2% of the surfactant Surfynol 465. Results for Dyes 2 and 3 are not included as they were not sufficiently water 10 soluble. Results using commercial dyes Fast Yellow 2 and Yellow 1 G are also included in the Table for comparison. All dyes were tested on a range of commercially available papers namely Canon PR101, SEC PM (from Seiko Epson).

ON, HO3S ó:N N Dye 7 OH HO3S:3 N'>N::, 'N NósO3H Yellow 1G OMe OMe CO2H CO2H

N Fast Yellow 2 HOCK Ns!'N '[)N N cO2H

cN' Table Dye Substrate RODa) La) ha) ba) ca) ha) LF 100HRs DE FY2 PR101 0.95 89 9 93 94 96 5.4

control SEC PM 0.95 88 -12 94 95 97 2.4

Y1G PR101 1.398 84 -1 111 111 90 10.9

control SEC PM 1.442 85 -2 115 115 91 11.9

Dye 4 PR101 1.45 72 18 88 90 78 16.7 SEC PM 1.545 71 21 90 92 77 14.5

Dye 5 PR101 1.141 82 4 92 92 88 13.3 SEC PM 1.015 83 -3 88 88 92 16.3

Dye 6 PR101 1.107 79 5 84 85 87 19.5 SEC PM 1.076 80 1 85 85 90 26.8

Comparative PR101 0.946 79 11 70 71 81 66.5 Dye 7 SEC PM 0.684 88 -10 69 70 98 71.3

Dye 9 PR101 0.6 91 -12 63 64 101 11.5 SEC PM 0.6 90 -14 68 70 102 3.7

= Dye 10 PR101 1.5 76 20 94 96 78 55.8 SEC PM 1.6 78 13 102 102 83 19.2

Dye 11 PR 101 1.4 7.6 18 91 92 79 26.0 SEC PM 1.4 79 12 101 102 83 10.5

Dye 12 PR 101 0.9 85 -3 79 79 92 11.9 SEC PM 0.9 86 -6 83 83 94 5.0

a) ROD is relative optical density; L, a and b are the colour coordinates; h is the hue 5 angle; C is chrome value; LF is lightfastness measured over 100 hours The above results show that the novel metallised dyes of this invention exhibit far superior properties to the unmetallised dye (comparative Dye 7) both in terms of optical

Glut density and lightfastness. Lightfastness and optical density for all metallised dyes were good.

Claims

1. A water soluble compound of Formula (1) or a salt thereof: y (N N y1 M X1 L 12 L3

L Formula (1) wherein: Y is an electron withdrawing group; y1 is H,alkyl or aryl, OR or NR2 in which each R independently is H. optionally 10 substituted alkyl or optionally substituted aryl; or Y and y1 together form a 5- or 6- membered ring; X1 is a group or atom which co-ordinates with M; M is hexa co-ordinate metal; G is a group of Formula (2), (3) or (4); and 15 L1, L2 and L3, each independently represent ligands required to complete hexa coordinate geometry around metal M; S. Ar* X* Formula (2) Sac* Z N* Formula (3)

i* Z Formula (4) wherein: 5 S is a water solubilizing group; Ar is a benzene or naphthalene group in which X is located ortho to the azo group; X is a group or atom which co-ordinates with M; Z provides atoms or groups which complete an optionally substituted 5- or 6 membered aromatic heterocyclic ring; 10 Ring A is an optionally substituted aromatic ring; Ring B is an optionally substituted 5- or 6-membered aromatic heterocyclic ring; n is 0, 1, 2 or 3; and the * signify the points of attachment of the groups of Formulae (2), (3) and (4) to the N and M atoms in the compound of Formula (1).

2. A compound according to Claim 1 in which G is a group of Formula (2),

which is shown as the compound of Formula (5): y ANN WIN/Y

n i:X \ L 12 L

L Formula (5) wherein: Y is an electron withdrawing group; YE is H,alkyl or aryl, OR or NR2 in which each R independently is H. optionally substituted alkyl or optionally substituted aryl; 2 5 or Y and Y' together form a 5- or 6- membered ring; X, is a group or atom with co- ordinates with M; M is hexa co-ordinate metal;

/ - \ L', L2 and L3, each independently represent ligands required to complete hexa coordinate geometry around metal M; S is a water solubilizing group; Ar is a benzene or naphthalene group in which X is located ortho to the azo group; 5 X is a group or atom which co-ordinates with M; Ring A is an optionally substituted aromatic ring; Ring B is an optionally substituted 5- or 6-membered aromatic heterocyclic ring; and n is 0, 1, 2 or 3.

3. A compound according to Claim 1 in which G is a group of Formula (3), this is shown below in the compound of Formula (6): y S. IN.

L' L2 L3

Formula (6) 1 5 wherein: Y is an electron withdrawing group; Y' is H, alkyl or aryl, OR or NR2 in which each R independently is H. optionally substituted alkyl or optionally substituted aryl; or Y and y1 together form a 5- or 6- membered ring; 2 0 X' is a group or atom with coordinates with M; M is hexa co-ordinate metal; L1, L2 and L3, each independently represent ligands required to complete hexa coordinate geometry around metal M; S is a water solubilizing group; 2 5 Z provides atoms or groups which complete an optionally substituted 5- or 6 membered aromatic heterocyclic ring; and nisO, 1,20r3.

4. A compound according to Claim 1 in which G is a group of Formula (4), 30 which is shown as the compound of Formula (7);

y INS \=/ 1 (:L, l2 L Formula (7) wherein: Y is an electron withdrawing group; 5 Y' is H,alkyl or aryl, OR or NR2 in which each R independently is H. optionally substituted alkyl or optionally substituted aryl; or Y and Y' together form a 5- or 6- membered ring; X' is a group or atom with co-ordinates with M; M is hexa co-ordinate metal; 10 L', L2 and L3, each independently represent ligands required to complete hexa coordinate geometry around metal M; Z provides atoms or groups which complete an optionally substituted 5- or 6 membered aromatic heterocyclic ring; Ring A is an optionally substituted aromatic ring; 15 Ring B is an optionally substituted 5- or 6-membered aromatic heterocyclic ring; and n is 0, 1, 2 or 3.

5. A liquid ink composition suitable for ink jet printing which comprises an aqueous 2 0 liquid medium and, dissolved therein, a compound as claimed in any preceding claim.

6. A process for printing an image on a substrate comprising applying thereto by means of an ink jet printer a liquid ink composition according to claim 5.

2 5

7. A process according to claim 6 in which the substrate is paper or a plastic sheet.

8. A process according to claim 6 in which the substrate is a textile material.

9. An ink jet printer cartridge containing a liquid ink composition according to claim 5.