Synthesis and Study of Highly Sensitive and Selective Fluorescent Receptors Based on Fluorescence Enhancement for Cu~(2+)

Two novel fluorescent receptors,1-(2-substituted-benzylidene)-4-phenylsemicarbazide(1-2,substituent=O—CH3;H),were designed and synthesized.Their structures were characterized with NMR spectroscopy and HRMS spectroscopy.Their responses to such metal ions as Zn2+,Cu2+,Pb2+,Cd2+,Hg2+,Ni2+,Mg2+ and Ca2+ in acetonitrile were investigated with absorption spectroscopy and fluorescence spectroscopy.The results demonstrated that both receptors,especially receptor 2,showed good fluorescent recognition capability for Cu2+.Its florescence spectra showed a highly selective and sensitive response to Cu2+ with a 613-fold enhancement in its fluorescence emission and a low detection limit of 3.05×10-8 mol/L.The mechanism of fluorescence enhancement induced by Cu2+ is briefly discussed in this paper.