Bifunctional Cu(2+)/Fe(3+) Probe with Independent Signal Outputs Based on a Photochromic Diarylethene with a Dansylhydrazine Unit

[Image: see text] 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 Fe(3+) and Cu(2+) with independent fluorescence signal outputs. In the presence of Fe(3+), 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 Cu(2+), 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 Fe(3+) and 3.49 × 10(–7) mol L(–1) for Cu(2+), respectively. From the unimolecular platform, two molecular logic circuits were constructed using the fluorescence emission intensity at 557/494 nm (Fe(3+)/Cu(2+)) as the outputs and the combined stimuli of Fe(3+)/ethylenediaminetetraacetic acid, Cu(2+), and UV/vis as the inputs. In addition, the sensor was successfully used to determine Fe(3+) in water samples from Ganjiang River and soil samples from Nanchang fields.