Origin of Large Near-Infrared Solvatochromism of 18π-Electron Aromatic Monohydroxybenziphthalocyanine

Abstract

Near-IR (NIR) organic dyes have been widely utilized in life sciences and materials science. Herein we report an unusually large NIR solvatochromism of monohydroxybenziphthalocyanine, an analogue of 18π-electron aromatic phthalocyanine in which a single isoindoline unit is replaced with a phenol ring. The solvatochromism is attributed to deprotonation of the phenol moiety in highly polar solvents, leading to the generation of a strongly NIR-absorptive 18π-electron aromatic quinoidal monoanion.