Molecular Structure, Vibrational Analysis, Hyperpolarizability and NBO Analysis of 3-Methyl-Picolinic Acid Using SQM Calculations

Abstract

In this study, FT-IR and FT-Raman spectra of 3-methyl picolinic acid (MPA) are recorded in the ranges 4000–450 cm^–1 and 4000–50 cm^–1, respectively. The optimized geometry is obtained by scaled quantum mechanical calculations using density functional theory employing the B3LYP functional with the 6–311++G(d,p) basis set. Vibrational assignments are suggested for all the fundamental vibrations unambiguously, using the potential energy distribution obtained in the computations. The rms error between the observed and calculated frequencies is found to be 8.48 cm^–1. The dipole moment, polarizability, and hyperpolarizability values are computed to study the NLO behavior of the molecule. The NBO analysis is made to study the stability of the molecule arising from hyperconjugative interactions and charge delocalization.