Synthetically expedient water-dispersible IR dyes having improved lightfastness

摘要

The present invention provides an IR-absorbing naphthalocyanine dye of formula (I): wherein M is selected from Ga(A¹); A¹ is an axial ligand selected from -OH, halogen (preferably Cl), -OR³, a hydrophilic ligand and/or a ligand suitable for reducing cofacial interactions; R¹ and R² may be the same or different and are selected from hydrogen or C_1-12 alkoxy (preferably C_1-6 alkoxy); R³ is selected from C_1-12 alkyl, C_5-12 aryl, C_5-12 arylalkyl or Si(R^x)(R^y)(R^z); and R^x, R^y and R^z may be the same or different and are selected from C_1-12 alkyl, C_5-12 aryl, C_5-12 arylalkyl, C_1-12 alkoxy, C_5-12 aryloxy or C_5-12 arylalkoxy; W is a hydrophilic group; n1 is 0, 1, 2 or 3; n2 is 0, 1, 2 or 3; n3 is 0, 1, 2 or 3; n4 is 0, 1, 2 or 3; provided that at least one of n1, n2, n3 or n4 is greater than 0. Dyes of this type are especially suitable for use in netpage and Hyperlabel(TM) systems.