A novel fluorescence "turn-on" sensor based on a photochromic diarylethene for the selective detection of Al(III)

A novel photochromic diarylethene with a triazole-containing 2-(2'-phenoxymethyl)-benzothiazole group has been synthesized via "click" reaction. The diarylethene exhibited good photochromism and photoswitchable fluorescence. Its fluorescence emission intensity was enhanced 7-fold by acids, accompanied by the red-shift of emission peak from 526nm to 566nm and the concomitant color change from dark to bright flavogreen. The diarylethene selectively formed a 1:1 metal complex with Al³⁺, resulting in a "turn-on" fluorescence signal. The complexation - reaction between Al³⁺ and the diarylethene is reversible with the binding constant of 2.73×10³Lmol^-1. The limit of detection (LOD) of Al³⁺ was determined to be 5.94×10^-8molL^-1. Based on this unimolecular platform, a logic circuit was fabricated using the fluorescence emission intensity at 572nm as the output and the combined stimuli of Al³⁺/EDTA and UV/Vis as the inputs.