Patent ID: 6995274

Claim:
A compound of the formula (I): wherein Z is O; R 1 –R 5 are each independently H, alkyl, halo, carboxyl, amino, or SO 3 − Cat + , wherein Cat + is a cation and at least one of R 1 –R 5 is SO 3 − Cat + ; R 6 and R 7 are each H, alkyl, or optionally, together with the group to which they are bonded, form a ring, said ring being optionally substituted; m and n are each independently integers from 0 to 5; X and Y are CR 19 C 20 , wherein R 19 and R 20 are each independently alkyl, or optionally form a ring together with the carbon atom to which they are bonded; R 8 and R 13 are each independently alkyl, (CH 2 ) r R 25 or (CH 2 ) r R 18 ; wherein at least one of R 8 and R 13 is (CH 2 ) r R 18 and wherein r is an integer from 1 to 50, R 25 is a functional group selected from the group consisting of hydroxyl, thioacetyl, and sulfonato, and R 18 is a linking group selected from the group consisting of mercapto, amino, haloalkyl, phosphoramidityl, N-hydroxy succinimidyl ester, sulfo N-hydroxy succinimidyl ester, isothiocyanato, iodoacetamidyl, and maleimidyl that can react with a carboxyl, hydroxyl, amino, or thiol group on a biomolecule; and R 9 –R 12 and R 14 –R 17 are each independently H, alkyl, halo, amino, sulfonato, R 21 COOH, R 21 OR 22 , R 21 SR 22 , or R 21 COOR 22 wherein R 21 is a bond or alkylene and R 22 is alkyl, or optionally R 11 and R 12 together with the atoms to which they are bonded form an aromatic ring, or optionally R 16 and R 17 together with the atoms to which they are bonded form an aromatic ring.