Manganese(II) catalyzed synthesis of bis(N-cyclohexylthiourea) derived from thiosemicarbazide: Structural characterization, fluorescence, cyclic voltammetry, Hirshfeld surface analysis and DFT calculation

Abstract

A new compound bis(N-cyclohexylthiourea) (H2chth) has been synthesized and characterized with the aid of elemental analyses, IR, NMR and single crystal X-ray diffraction data. Compound H2chth crystallizes in triclinic system with space group P-1. During the course of reaction, the cyclohexyl isothiocynate moiety of the substituted thiosemicarbazide undergoes tautomerization and rearrangement into the corresponding carbothioamide moiety in the presence of manganese(II) acetate. The interaction of H2chth with different metal ions in methanol solution is studied and it shows interesting red shifts with Mn2+, Co2+, Ni2+, Cu2+, Zn2+ and Cd2+ ions which suggests that compound H2chth may be a useful probe for sensing of these metal ions. Cyclic voltammetric studies of H2chth and its interaction with different metal ions exhibit complete irreversible redox behavior. Compound H2chth exhibits emission at 27322 cm−1 upon excitation at 37037 cm−1. The emission spectra of different metal ions with H2chth exhibit less intense emissions as compared to the free H2chth. The structure of compound H2chth is stabilized via intermolecular N-H···S and C-H···S hydrogen bonding. The geometry of the compound H2chth has been optimized using the B3LYP density functional theory method and the results are compared with the X-ray diffraction data. The calculated geometrical parameters corroborate with the experimental data. Frontier molecular orbital analysis suggests that compound H2chth is soft and highly reactive. Hirshfeld surface map and 2D finger print plot were used to explore the intermolecular interactions of H2chth.