Bifunctional Cu2+/Fe3+ Probe with Independent Signal Outputs Based on a Photochromic Diarylethene with a Dansylhydrazine Unit.

Abstract

A novel dual-response fluorescent sensor based on a diarylethene photoswitching unit and a dansylhydrazine functional group has been synthesized. The compound exhibited high selectivity for Fe3+ and Cu2+ with independent fluorescence signal outputs. In the presence of Fe3+, the sensor formed a 1:1 metal complex, resulting in a remarkable “turn-off” fluorescence signal. On the other hand, its fluorescence intensity was notably enhanced (turn-on) and a color change from bright yellow to bright blue was observed when the sensor interacted with Cu2+, which was due to the hydrolysis reaction of the dansyl acid dye, as confirmed by high-resolution mass spectrometry–electrospray ionization and infrared spectrum. The detection limits were 9.73 × 10–8 mol L–1 for Fe3+ and 3.49 × 10–7 mol L–1 for Cu2+, respectively. From the unimolecular platform, two molecular logic circuits were constructed using the fluorescence emission intensity at 557/494 nm (Fe3+/Cu2+) as the outputs and the combined stimuli of Fe3+/ethylenediaminetetraacetic acid, Cu2+, and UV/vis as the inputs. In addition, the sensor was successfully used to determine Fe3+ in water samples from Ganjiang River and soil samples from Nanchang fields.