DFT analysis for structure, vibrational assignments, and molecular properties of medicinally important isoquinoline

Abstract

2-Benzanine, also recognized as isoquinoline or benzo pyridine, acts as a weak tertiary base with diverse biological and pharmacological effects. These include potential activities against Parkinson’s disease, antimalarial, anti-HIV, insect growth, anticancer, antibiotic, antileukemic properties, and the ability to serve as a chiral ligand scaffold. In this study, the B3LYP technique and the basis set 6-311++G(d, p) were employed for both computational and experimental examinations of isoquinoline using density functional theory (DFT). The findings revealed that isoquinoline possesses a dipole moment of 2.004 D and rotational constants (GHz) of 3.101, 1.22, and 0.875. Various tests, including IR, UV–visible, HNMR, and binding energies, corroborated the experimental results. Analyzing the computed energy difference between the highest occupied molecular orbital (HOMO) at −5.581 eV and the lowest unoccupied molecular orbital (LUMO) at 1.801 eV indicated the stability of isoquinoline, with an energy gap of 3.78 eV. The electron polarizability and chemical hardness values were found to be 1.89 and 0.529, respectively. Drug-likeness tests suggest that isoquinoline could function as an antibiotic, given its similarity in effects to other compounds such as isoquinoline, quinolone, debrisoquine, palmatine, columbamine, and jatropine.