Near-infrared cyanine dyes and conjugates thereof

The invention relates to the field of optical imaging. More specifically, the present invention relates to compounds of the cyanine family with near-infrared emission characterized by improved physicochemical and biological properties, and to conjugates thereof with biological ligands. The invention also relates to the use of these compounds as optical diagnostic agents in the imaging or therapy of solid tumors, to processes for their preparation and to compositions comprising them. The compounds have the formula (I) wherein X is a direct bond or-O-; y is a group selected from a linear or branched C1-C6 alkyl group, a C3-C7 cycloalkyl group and a heterocyclic group, which is substituted by at least two hydroxyl groups; r1 and R2 are each independently a linear or branched C1-C6 alkyl group, which is substituted by a group selected from the group consisting of-SO3H,-COOH,-CONH2, and-COO-C1-C6 alkyl groups; and R3 is hydrogen,-SO3H or a linear or branched C1-C6 alkyl group substituted with-COOH or-CONH-Y, where