Structural Characterization, DFT, Hirshfeld Surface Analysis and Antibacterial Activity of a Schiff Base Derived from Cyclohexanediamine

A new Schiff base derived from cyclohexanediamine and 3-methylsalicylaldehyde was obtained. The Schiff base, 6,6'-((1E,1'E)-(cyclohexane-1,2-diylbis(azanylylidene ))bis( methanylylidene ))bis( 2-methylphenol), (AD2Me) was characterized through elemental analysis, infrared, UV-Vis, H-1 and C-13 nuclear magnetic resonance (NMR) spectroscopy. The structure of the grown crystal was elucidated by using single crystal X-ray diffraction technique. The compound crystallized in the triclinic system, P-1 space group. The cell length and volume for AD2Me are a = 10.4582(11) angstrom, b =10.8141(9) angstrom, c =18.7472(14) angstrom, a = 90.629(7)degrees, beta = 92.444(7)degrees, gamma = 109.561(9)degrees and V =1995.3(3) angstrom(3), respectively. The crystal structure is stabilized by intramolecular hydrogen bond O-H center dot center dot center dot N and intermolecular hydrogen bonds C-H center dot center dot center dot O, C-H center dot center dot center dot pi and pi center dot center dot center dot pi. The B3LYP method was used to calculate the optimized structure of the molecule through density functional theory (DFT) using the 6-311G++(d, p) basis set and the results of the conformation analysis was in good agreement with the crystal structure determined by x-ray single crystal diffraction. Additionally, the molecular electrostatic potential, frontier molecular orbitals and chemical reactivity descriptors of AD2Me were further investigated using DFT, revealing the electronic properties of the compound. A Hirshfeld surface analysis was performed to analyze intermolecular interactions in the crystal structure. The compound showed no significant activity against Staphylococcus aureus subsp. aureus Rosenbach (ATCC 6538) and Streptococcus mutans Clarke (ATCC 700610). (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

A new Schiff base compound AD2Me was synthesized and characterized using various techniques including single crystal X-ray diffraction, NMR spectroscopy. The crystal structure and molecular properties of AD2Me were verified by density functional theory calculations. The antibacterial activity testing indicated that the compound showed no significant activity against two bacterial strains.