The photochromism, light harvesting and self-assembly activity of a multi-function Schiff-base compound based on the AIE effect

Abstract

Aggregation-induced emission (AIE) luminogens with photochromic properties show strong potential in molecular switches, photo-controllable materials, photo-patterning, etc. In this paper one Schiff-base compound 1 exhibited reversible photo-controllable colour changes in solid states due to the typical ESIPT effect: the crystal turned from colourless to yellow after ultraviolet light irradiation and became colourless again in the dark. Second, 1 presented a good aggregation-induced emission (AIE) activity in aqueous solution. Third, highly efficient light-harvesting systems are successfully fabricated in aqueous solution based on AIE(1) and rhodamine B, where AIE(1) acts as an energy donor and rhodamine B acts as an acceptor. Fourth, addition of Al³⁺ or Cu²⁺ ions destructed the N⋯H–O hydrogen bond and induced the rearrangement or destruction of AIE(1) with a different emission. Last, theoretical calculations of deprotonated 1 indicated that the protons on phenolic hydroxyl groups have a great influence on the fluorescence properties of 1. These results demonstrated that compound 1 is a multi-functional organic luminescent material exhibiting excellent photochromism, light-harvesting and AIE properties.