Synthesis and use of croconaine compounds

The present disclosure provides compositions and methods for the synthesis and use of croconaine compounds. The disclosed compounds are easily prepared from croconic acid. A halothiophene is reacted with an alkanolamine, the resulting aminothiophene is modified by appending a desired functional group to the hydroxyl group, and the modified aminothiophene is reacted with croconic acid to form the final compound. Applications of such croconaine compounds include photothermal imaging, photothermal therapy, light-activated drug release, and tissue welding.