STRUCTURAL, ELECTRONIC AND NATURAL BONDING ORBITALS (NBOS) ANALYSIS OF CHLOROBENZALDEHYDE SCHIFF BASES: A DFT STUDY

Abstract

This study investigates the reactivity and stability of Schiff bases (S1–S2), focusing on their geometric and electronic properties. These compounds are of interest due to their potential applications stemming from their conjugated systems and functional groups. The study aims to explore their chemical reactivity descriptors, intramolecular and intermolecular charge transfer behavior, and stability. Additionally, the spectral properties of the Schiff bases were examined through simulated UV-Vis and FTIR spectra, with particular attention to π–π* transitions associated with aromatic rings and C=N linkages. Density Functional Theory (DFT) calculations were carried out using the B3LYP functional and the 6-311G(d,p) basis set. Global reactivity parameters including ionization potential (IP), electron affinity (EA), chemical hardness, softness, electronegativity, and electrophilicity were derived from the frontier molecular orbitals (FMO). Hirschfeld surface analysis and Natural Bond Orbital (NBO) analysis were also performed at the same theoretical level to assess molecular interactions and charge transfer. Simulated UV-Vis and FTIR spectra were computed to further support the electronic and vibrational characterization of the Schiff bases.