A novel uracil-based chemosensor for sequential detection of copper (II) and cyanide ions and its application in real samples

Abstract A simple uracil based chemosensor (UraCS) has been developed for sequential detection of Cu2+ and CN− in aqueous acetonitrile solution. The sensor UraCS showed a high selectivity, high sensitivity and quick response to copper ions in the presence of other competing cations including Cd2+, Fe2+, Hg2+, Al3+, Ni2+, Ba2+, Ca2+, Cr3+, Co2+, Zn2+, Cu2+, Pb2+, Ag+, Fe3+ and K+. In the presence of Cu2+, UraCS provided a distinct color change from colorless to dark yellow forming a complex with a 2:1 stoichiometry and reverse color change after addition of CN‾ to the probe containing UraCS-Cu2+ complex. More importantly, the results confirmed that the UraCS has widely linear detection range of 3.0 to 150 µM toward Cu2+ ions. The calculated limit of detection for Cu2+ ions was low as 0.28 μM. Moreover, interaction of UraCS with Cu2+ causes a significant fluorescence quenching at 378 nm. UraCS-Cu2+ complex could be successfully applied to detect cyanide ions via Cu2+ displacement approach. The free UraCS was recovered after adding the CN‾ ions in a few seconds due to the formation of the stable copper cyanide complex Cu(CN)x. The DFT calculation was also performed for better understanding of the Cu2+ sensing mechanism. Furthermore, chemosensor UraCS was successfully utilized in the preparation of test strips and supported silica gel for the detection of Cu2+ and CN− ions from aqueous environment and real water samples.