Analytical and computational investigation on host-guest interaction of cyclohexyl based thiosemicarbazones: Construction of molecular logic gates using multi-ion detection

摘要

Two novel cyclohexyl based thiosemicarbazones, H2L1 and H3L2, are synthesized and characterized. The anion and cation sensing properties of the two receptors has been unveiled as an effective ratiometric and colorimetric sensor for selective and rapid detection of fluoride, copper and cobalt ions. The H2L1 shows selective sensing towards F- and Cu2+ at 429 and 393 nm, whereas, H3L2 can detect F-, Cu2+ and Co2+ at 350, 393 and 408 nm respectively. The fluoride-sensing mechanism of the receptors has been investigated by means of the DFT and TD-DFT methods. The experimental UV-vis and fluorescence spectra are well reproduced by the calculated vertical excitation energies in the ground state and the first singlet excited state. The present theoretical study indicates that the deportation was taken from the 'NH' proton which is closer to the imine group, which has been confirmed by natural bond orbital (NBO) analysis and the potential energy curve (PES) of ground state for the function of N-H bond. The absorption and emission response for receptors with and without F-, Co2+ and Cu2+ ions can mimic multiple logic gate such as NOR, XNOR, OR and TRANSFER gates.