Synthesis, spectroscopic characterization, single crystal XRD, Hirshfeld Surface analysis and theoretical studies (DFT) of 4-adamantyl-(2-(substitutedbenzylidene)hydrazinyl)thiazoles

Abstract

In present work, two novel adamantyl based thiazoles were synthesized via simple cyclization reaction of 1-(substitutedbenzylidene)thiosemicarbazides (2) and 1-adamantyl bromomethyl ketone. The structures of resulting compounds 3a and 3b were established with the help of spectro-analytical techniques like; FTIR, 1H-, 13C-NMR and mass spectrometry. The final confirmation of the structures was done with single crystal XRD. All spectroscopic properties of the compounds were further investigated with Density Functional Theory (DFT). The quantum chemical calculations were performed through B3LYP method with 6-311G(d,p), ccPVTZ and ccPVDZ as basis sets to determine bond lengths, bond angles, dihedral angles, frontier molecular orbitals (FMOs) and molecular electrostatic potential (MEP), which revealed that the molecule 3b is strong electrophile while molecule 3a is moderate one. We have also compared the theoretical molecular vibrations and chemical shifts of the compounds with experimental data and results were in good agreement with each other. On the basis of respective correlation co-efficient (σ2) of calculation methods (6-311G(d,p), ccPVTZ and ccPVDZ) it is revealed that ccPVTZ basis sets gave the best results. The MEP analysis revealed that electronegative elements in structure possess the maximum electronic cloud.