Colorimeric and fluorescence ON-OFF probe for acetate anion based on thiourea derivative: theory and experiment

Based on thiourea moiety, three colorimetric and fluorescent anion probes have been synthesized. Results indicated the probe 1 containing p-NO(2) group showed the strongest binding ability for AcO(-) among the anions tested (F(-), AcO(-), H(2)PO(4)(-), Cl(-), Br(-), I(-)), which was not influenced by the existence of other anions. The interaction of host-guest was accompanied with a dramatic color change from colorless to orange. However, the addition of various anions did not cause noticeable spectral response of the probes (2 and 3) containing o, m-NO(2) groups. Theoretical investigation demonstrated the electron transition of the highest LUMO aroused the red-shift phenomenon in UV-vis spectra of 1-anion.