Structural, Conformational and Spectroscopic Investigations of a Biologically Active Compound: L-Dopa

Abstract

Highlights: What are the main findings? The L-dopa molecule has 108 stable configurations. Vibrational analysis confirms the existence of a dimeric form of L-dopa and a strong IR band peak at 2770 cm−1 suggests its OH forms. L-dopa molecules are found to be chemically soft and biologically active in nature. Strong active sites are near the O and H atoms of the OH and COOH groups. What is the implication of main findings? L-dopa molecule would be a good choice for medicinal application. Multiple active sites play significant role for its chemical activities. Structural, conformational and spectroscopic investigations of the L-dopa molecule were made at the b3lyp/6-311++g** level using the Gaussian 09 software. IR, Raman and UV-vis spectra were measured and analyzed in light of the computed spectral quantities. Total energy vs. dihedral angle scans yielded 108 pairs of stable conformers of L-dopa. All the conformers had energies above 500 K relative to the lowest-energy conformer C-I. The observed spectra could be explained in terms of the computed spectra of the lowest-energy dimer of the C-I monomer. MEP and HOMO-LUMO analysis were carried out, and barrier heights and bioactivity scores were determined. The positive bioactive scores represent its higher medicinal and pharmaceutical applications. The present investigation suggests that the molecule has three active sites with moderate bioactivity. © 2023 by the authors.