Rigidized trimethine cyanine dyes

1. A compound (I) of formula:

substituted by groups R 2 –R 9 , wherein groups R 6 , R 7 , R 8 and R 9 are attached to the atoms of the Z a and Z b ring structures;

R 2 to R 9 are the same or different and are —R 10 or -L-R 10 where R 10 is selected from hydrogen, halogen, amide, C 1 –C 6 alkoxy, nitro, cyano, aryl, heteroaryl, sulphonate, quaternary ammonium, guanidium, hydroxyl, phosphate, phosphonate, optionally substituted amino, azido, sulphydryl, carboxyl, carbonyl and reactive groups selected from succinimidyl ester, isothiocyanate, anhydride, haloacetamide, maleimide, sulphonyl halide, phosphoramidite, acid halide, alkylimidate, hydrazide and carbodiimide, and L is selected from the group consisting of a straight or branched C 1-20 alkyl chain, a C 2-20 monoether or polyether and a C 2-20 atom chain containing up to four secondary amide linkages;

R 1 is selected from hydrogen, aryl, heteroaryl, cyano, nitro, aldehyde, halogen, hydroxy, amino, quaternary amino, acetal, ketal, phosphoryl, sulphydryl, and alkyl groups optionally substituted by amino, C 1-4 alkyl-substituted amino, quaternary amino, aldehyde, ketone, acetal, ketal, halo, cyano, aryl, heteroaryl, hydroxyl, sulphonate, sulphate, carboxylate, amide and nitro;

A is selected from O, S and NR 11 where R 11 is the substituted amino radical:

where R′ is selected from hydrogen, a C 1-4 alkyl and aryl and R″ is selected from C 1-18 alkyl, aryl, heteroaryl, an acyl radical having from 2–7 carbon atoms , and a thiocarbamoyl radical;

X and Y may be the same or different and are selected from bis-C 1 –C 4 alkyl and C 4 –C 5 spiro alkyl substituted carbon, oxygen, sulphur, selenium, CH═CH, and N—W wherein N is nitrogen and W is selected from hydrogen, a group —(CH 2 ) n R 12 where n is an integer from 1 to 26 and R 12 is selected from hydrogen, amino, aldehyde, acetal, ketal, halo, cyano, aryl, heteroaryl, hydroxyl, sulphonate, sulphate, carboxylate, substituted amino, quaternary amino, nitro, primary amide and substituted amide;

Z a and Z b each represent the atoms necessary to complete one, or two fused aromatic rings each ring having six carbon atoms;

provided that when X and Y are other than carbon, at least one of R 2 –R 9 represents -L-R 10 or R 10 wherein R 10 is said reactive group or,

when X and Y are different and are selected from O and Se, at least one of R 1 –R 9 is other than hydrogen, methyl, phenyl or naphthyl.

2. A compound (I) according to claim 1 wherein R 1 is selected from hydrogen, aryl, heteroaryl, cyano, halogen, alkyl groups of twenty-six carbon atoms or less and —(CH 2 ) n Q where 1<n<26 and Q is selected from amino, aldehyde and hydroxyl and R 2 , R 3 , R 4 and R 5 are hydrogen.

3. A compound selected from:

i) 6,7,9,10-Tetrahydro-2,14-carboxymethyl-16,16,18,18-tetramethyl-7aH,8aH-bisindolinium[3,2-a;3′2′-a′]pyrano[3,2-c;5,6-c′]dipyridin-5-ium (Compound I);

ii) 8,9,11,12-Tetrahydro-3,17-disulphonato-20,20,22,22-tetramethyl-9aH,10aH-bisbenz[e]indolinium[3,2-a,3′2′-a]pyrano[3,2-c;5,6-c′]dipyridin-7-ium (Compound II);

iii) 6,7,9,10-Tetrahydro-2-carboxymethyl-14-sulphonato-16,16,18,18-tetramethyl-7aH,8aH-bisindolinium[3,2-a,3′2′-a]pyrano[3,2-c;5,6-c′]dipyridin-5-ium (Compound III);

iv) 6,7,9,10-Tetrahydro-2-carboxymethyl-14-sulphonato-16,16,18,18-tetramethyl-7aH,8aH-bisindolinium[3,2-a,3′2′-a]pyrano[3,2-c;5,6-c′]dipyridin-5-ium, glycinamide (Compound IV);

v) 6,7,9,10-Tetrahydro-2-carboxymethyl-14-sulphonato-16,16,18,18-tetramethyl-7aH,8aH-bisindolinium[3,2-a,3′2′-a]pyrano[3,2-c;5,6-c′]dipyridin-5-ium, N-(2-aminoethylcarboxamide) (Compound V);

vi) 6,7,9,10-Tetrahydro-2-(N-formyl)aminomethyl-14-sulphonato-16,16,18,18-tetramethyl-7aH,8aH-bisindolinium[3,2-a,3′2′-a]pyrano[3,2-c;5,6-c′]dipyridin-5-ium (Compound VI);

vii) 6,7,9,10-Tetrahydro-2-hydroxyethyl-16,16,18,1 8-tetramethyl-7aH,8aH-bisindolinium[3,2-a,3′2′-a]pyrano[3,2-c;5,6-c′]dipyridin-5-ium (Compound VII);

viii) 6,7,8,10-Tetrahydro-14-carboxymethyl-16,16-dimethyl-7a-8a-benzothiazolenine-indolenine-[3,2-a]-benzthiazolyl [3′2′-a]-pyrano[3,2-c;5,6-c′]dipyridin-5-ium (Compound VIII);

ix) 6,7,8,8a,9,10-Hexahydro-2,14-disulphonato-8-(4-carboxy-anilino)-16,16,18,18-tetramethyl-7aH-bis-indolinium[3,2-a;3′2′-a′]pyrido[3,2-c;5,6-c′]dipyridin-5-ium (Compound IX);

x) 6,7,9,10-Tetrahydro-14-carboxymethyl-16,16-dimethyl-7a-8a-quinolino-indolenium-[3,2-a,3′2′-a]-pyrano[3,2-c;5,6-c′]dipyridin-5-ium (Compound X).

4. A method for producing a compound (I) according to claim 1 or 2 comprising

(i) providing a compound (II) of the following formula:

wherein R is methyl or ethyl; and

(ii) treating said compound (II) under acid conditions to form the compound of formula (I).