Electronic structure perturbation induced by fluorine substitution in methylamine: a comparative DFT, spectroscopic and molecular recognition study

Abstract

This study presents a comparative theoretical investigation of methylamine and fluoromethylamine to explain the electronic and spectroscopic consequences of single fluorine substitution. Geometry optimization and electronic structure calculations were carried out at the B3LYP/6-311G(d, p) level within the framework of density functional theory. Frontier molecular orbital analysis showed that fluorination significantly reduced the HOMO-LUMO energy gap, suggesting enhanced electronic reactivity of the fluorinated derivative. Global reactivity descriptors further revealed an increase in electrophilic character following fluorine substitution. Simulated NMR and UV-Vis spectra showed noticeable spectral changes associated with charge redistribution and fluorine-induced polarization effects. Molecular electrostatic potential and density of states analyses confirmed substantial change in the electronic environment of the molecule. In addition, molecular docking calculations were performed to evaluate the molecular recognition behavior of both compounds toward RhCG, providing insight into their possible interaction propensity. The results show that minimal structural modification by fluorination can induce measurable changes in the electronic structure, spectroscopic response, and exploratory molecular-recognition tendency of methylamine.