Dyes with changeable solubilities, and methods for their use

A method of dying a substrate, the method comprising:

• contacting the substrate with an aqueous solution of a dye compound for a time period sufficient to covalently bond a hydrophilic dye moiety of the dye compound to the substrate;
• and
• exposing the substrate to a stimulus;
• wherein:
• the dye compound comprises:
• the hydrophilic dye moiety;
• and
• a hydrophobic moiety bonded to the hydrophilic dye moiety through a linker moiety;
• and
• the linker moiety is configured to be cleaved in response to a stimulus;
• the dye compound is represented by Formula I, II, III, or IV:
• Z is the hydrophobic moiety;
• L is the linker moiety;
• Y is a phenyl or a naphthyl group;
• X is H, Cl, Br, F, or I;
• Ra is a halogen, or —NRb—W group;
• Rb is H or an alkyl group;
• R1, R2, R3, R4, R5, R6, and R7 may be the same or different and are independently H, Cl, Br, F, I, —NO2, —OH, alkyl, aryl, or —S(═O)3R12;
• R8, R9, R10, and R11 may be the same or different and are independently H or alkyl;
• R12 is H or an alkali metal;
• each Y independently comprises a phenyl or a naphthyl group;
• and
• W comprises a phenyl, naphthyl or anthracenyl group.