Synthesis, characterization, and molecular structure investigation of new tetrahydrobenzo[b]thiophene-based Schiff bases: A combined experimental and theoretical study

Abstract

Five new heterocyclic Schiff base derived from tetrahydrobenzo[b]thiophene were synthesized by condensation reaction of 2-amino-4, 5, 6, 7- tetrahydrobenzo[b]thiophene-3-carbonitrile with aromatic aldehydes in dimethylformamide containing ZnCl2. The new Schiff bases were characterized on the basis of FT-IR, 1H NMR, and 13C NMR spectral data. In addition, the optimized geometries and assignment of the 1H NMR chemical shifts of the synthesized compounds were computed using the density functional theory (DFT) approaches. Good agreement between the DFT-calculated 1H NMR chemical shifts and the corresponding experimental values confirms suitability of the optimized geometries for the synthesized Schiff bases. Characteristics of the bonding interactions have been explored using the quantum theory of atoms in molecule (QTAIM) analysis.