Intramolecular Interactions (O-H•••O, C-H•••N, N-H•••π) in Isomers of Neutral, Cation, and Anion Dopamine Molecules - A DFT Study on the Influence of Solvents (Water and Ethanol)

Abstract

Abstract The investigation reports the intramolecular interactions present in the isomers of neutral (DA0), anionic (DA-), and cationic (DA+) dopamine isomers in gas, water, and ethanol mediums. Isomers of Cation dopamine show no intramolecular interactions in the solvent. Neutral and anion isomers have O-H∙∙∙O, C-H∙∙∙N hydrogen bonds and N-H⸳⸳⸳π interactions. All the interactions are electrostatic in nature. In solvents, intramolecular interactions are elongated and thereby weakened. Natural charges from NBO analysis show that O-H∙∙∙O bonds and the N- H∙∙∙π interactions are the most and least polar, respectively, among all the three interactions. 1H NMR study reveals the inverse linear correlation between shielding constant and electron density in a solvent medium. Homo-Lumo energy gap indicates higher stability for neutral and cationic forms of dopamine isomers in water and ethanol medium.