Inkjet ink comprising metal-cyanine dye with improved water-solubility

1. An inkjet ink comprising an IR-absorbing dye which is a metal-cyanine complex of formula (I):

wherein

Q 1 , Q 2 , Q 3 and Q 4 are the same or different and are independently selected from the group consisting of: a C 3-20 arylene group and a C 3-20 heteroarylene group;

M is selected from the group consisting of: Ti(A 1 )(A 2 ), Zr(A 1 )(A 2 ), V(A 1 )(A 2 ), Si(A 1 )(A 2 ), Ge(A 1 )(A 2 ), Ga(A 1 ), Al(A 1 ), Mn(A 1 ), Fe(A 1 ), Sn(A 1 )(A 2 ) and Pb(A 1 )(A 2 ); and

A 1 and A 2 may be the same or different and are axial ligands of formula (IIIa)

wherein:

G represents a core unit having two or more branching positions;

g 1 is an integer from 2 to 8;

q 1 is 0 or an integer from 1 to 6;

each p 1 is independently selected from 0 or an integer from 1 to 6; and

each L is independently selected from the group consisting of:

H;

(CH 2 CH 2 O) y R 6 , wherein v is an integer from 2 to 5000 and R 6 is H, C 1-6 alkyl or C(O)C 1-8 alkyl,

SO 3 Z;

PO 3 Z;

C 1-12 alkyl-CO 2 Z;

C 1-12 alkyl-SO 3 Z;

C 1-12 -alkyl-PO 3 Z 2 ;

C 1-12 alkyl-OSO 3 Z;

C 1-12 -alkyl-OPO 3 Z 2 ; and

C 1-12 -alkyl-N + (R a )(R b )(R c );

C 1-12 alkyl-J,

and wherein:

Z is H, Li + , Na + , K + or NH 4 + ;

R a , R b , R c may be the same or different and are independently selected from the group consisting of: H, C 1-8 alkyl, C 6-12 arylalkyl and C 6-12 aryl; and

J is pyridinium, imidazolinium or pyrrolinium.

2. The inkjet ink of claim 1 , wherein Q 1 , Q 2 , Q 3 and Q 4 are the same.

3. The inkjet ink of claim 1 , wherein -G is a C atom, an N atom, a Si atom, a C 1-8 alkyl residue, a C 3-8 cycloalkyl residue, or a phenyl residue.

4. The inkjet ink of claim 1 , wherein g is 2, 3 or 4.

5. The inkjet ink of claim 1 , wherein A 1 and/or A 2 is a pentaerythritol derivative of formula (A), a triethanolamine derivative of formula (B), a phloroglucinol derivative of formula (C), or a 3,5-dihydroxybenzyl alcohol derivative of formula (D):

wherein is -L is as defined in claim 1 .

6. The inkjet ink of claim 1 , wherein Q 1 , Q 2 , Q 3 and Q 4 are selected from an arylene or heteroarylene group of the formula:

wherein

R 1 and R 2 may be the same or different and are selected from the group consisting of: from hydrogen, hydroxyl, C 1-12 alkyl, C 1-12 alkoxy, amino, C 1-12 alkylamino, di(C 1-12 alkyl)amino, halogen, cyano, thiol, C 1-12 alkylthio, nitro, carboxy, C 1-12 alkylcarbonyl, C 1-12 alkoxycarbonyl, C 1-12 alkylcarbonyloxy or C 1-12 alkylcarbonylamino;

T is a C 1-30 hydrocarbyl group;

E is selected from the group consisting of: —OH, —O − , C 1-6 alkyl, carboxy-C 1-6 alkyl, sulfo-C 1-6 alkyl, C 1-6 alkoxy, C 5-12 arylalkyl, C 1-6 alkylcarbonyl, C 5-12 arylalkylcarbonyl, C 1-6 alkoxycarbonyl and C 5-12 arylalkoxycarbonyl;

m is 0, 1 or 2;

n is 0, 1 or 2;

p is 0, 1 or 2; and

W is a hydrophilic group selected from the group consisting of: a PEG chain an ammonium group a sulfonic acid group and salts thereof; and a sulfonamide group.

7. The inkjet ink of claim 6 , wherein R 1 and R 2 are selected from the group consisting of: hydrogen and C 1-8 alkoxy.