Oxadiazole-based selective chemosensor for copper (II) based on fluorescence quenching

A highly selective and sensitive oxadiazole-based chemosensor, 2-(2-hydroxyphenyI)-5-(4-dimethylaminophenyl)-1,3,4-oxadiazole, was designed and synthesized. The UV-vis absorption and fluorescence behavior between chemosensor and Cu2+ ion were investigated in 9:1 (v/v) ethanol-Hepes buffer (pH = 7.0) solution. The fluorescence of the chemosensor can be dramatically quenched by Cu2+ ion in aqueous solution, whereas it was not any interference from other metal ions such as Al3+, Be+, Ca2+, Cd2+, Co2+ Cr3+, Fe3+ Hg2+, mg(2+), Na+, Ni2+, Pb2+ and Zn2+. The complex formed between chemosensor and Cu2+ ion is found to be 2:1 stoichiometry with an association constant of 6.38 x 10(4)M(-1). The detection limit for Cu2+ ion determination is 8.71 x 10(-7) mol L-1. In addition, the binding mode between chemosensor and Cu2+ ion was confirmed by 1H NMR and mass spectrometry. (C) 2016 Elsevier B.V. All rights reserved.