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

Two novel cyclohexyl based thiosemicarbazones, HL and HL, 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 HL shows selective sensing towards F and Cu at 429 and 393 nm, whereas, HL can detect F, Cu and Co 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 NH bond. The absorption and emission response for receptors with and without F, Co and Cu ions can mimic multiple logic gate such as NOR, XNOR, OR and TRANSFER gates.