Synthesis of diarylethene derivatives containing various heterocycles and tuning of light-emitting properties in a turn-on fluorescent diarylethene system

A novel series of diarylethenes incorporating different heterocycles and their N-methylated derivatives have been synthesized, and the products have been characterized by means of NMR. MS and elemental analysis. Each of the compounds displays photochromism and "turn-on" fluorescence properties upon irradiation with UV light. It has been found that both the nature of the heterocycle attached to the imidazole ring and methylation of the imidazole ring greatly affect the optical properties. The light-emitting properties can be easily tuned from blue light-emitting to yellow light-emitting fluorescence by varying the nature of the heterocycle or by simple modification of structures, which provides a new strategy for the design of novel fluorescent switches. Moreover, Cu2+, Hg-2, and Fe3+ greatly affect the fluorescence properties of diarylethene 4 in the photostationary state, so that these systems might be deployed in a novel molecular sensor for the detection of such cations by fluorescence recognition. (C) 2011 Elsevier Ltd. All rights reserved.