Quantum Chemical Evaluation of the Electronic Reactivity of Benzimidazole Macromolecules: A Computational Study

ABSTRACT A series of benzimidazole derivatives ( E1–E5 ) was synthesized and characterized by FT‐IR and 1 H‐NMR spectroscopy. DFT calculations at the B3LYP/6‐311G(d,p) level were performed to evaluate their electronic properties. Frontier molecular orbital analysis revealed that the HOMO–LUMO energy gap (ΔE) follows the order E1 ≈ E2 > E4 > E3 , with E3 exhibiting the smallest gap (0.142 a.u.), highest softness (σ ≈ 14.08), and highest electrophilicity index (ω ≈ 0.130), indicating superior electronic reactivity. These results demonstrate that functional group modifications, particularly the introduction of conjugated imine moieties, significantly influence electronic behavior, enabling rational selection of the most reactive candidates.