A new selective chromogenic and turn-on fluorogenic probe for copper(II) in solution and vero cells: recognition of sulphide by [CuL]

A new coumarin-appended thioimidazole-linked imine conjugate, viz. has been synthesized and characterized. has been found to recognize Cu(2+) selectively among a wide range of biologically relevant metal ions. The chemosensing behavior of has been demonstrated through fluorescence, absorption, visual fluorescence color changes, ESI-MS and (1)H NMR titrations. The chemosensor showed selectivity toward Cu(2+) by switch on fluorescence among the 18 metal ions studied with a detection limit of 1.53 μM. The complex formed between and Cu(2+) is found to be 1 : 1 on the basis of absorption and fluorescence titrations and was confirmed by ESI-MS. DFT and TDDFT calculations were performed in order to demonstrate the structure of and [CuL] and the electronic properties of chemosensor and its copper complex. This highly fluorescent [CuL] complex has been used to recognize sulphide selectively among the other allied anions. Microstructural features of and its Cu(2+) complex have been investigated by SEM imaging (scanning electron microscopy). The biological applications of were evaluated in Vero cells and it was found to exhibit low cytotoxicity and good membrane permeability for the detection of Cu(2+).