Modulation of the optical properties of thiazolinochlorin compounds by the regioselective introduction of aryl(ethynyl) substituents

Abstract

C7- and C8-selective bromination reactions of thiazolinochlorin S-(di)oxides were performed using N-bromosuccinimide. The regioselectivities, which were confirmed by 2D NMR analyses, were consistent with those of conventional chlorin compounds. Furthermore, aryl and arylethynyl substituents were introduced via Suzuki–Miyaura and Sonogashira cross-coupling reactions, respectively. Ultraviolet–visible absorption and fluorescence emission spectra of the brominated and aryl- and arylethynyl-substituted compounds were recorded to clarify the effects of substitution at the C7 and C8 positions on their optical properties. The modulated photoabsorption properties were also discussed based on computational studies.