Vibrational Spectroscopic Investigations, Electronic Properties, Molecular Structure and Quantum Mechanical Study of an Antifolate Drug: Pyrimethamine

The computational modelling supported by experimental results can explain the molecular structure, vibrational assignments, reactive sites and several structural properties. In this context, spectroscopic (FT-IR, FT-Raman NMR) analysis, electronic properties (HOMO LUMO energies) structure of pyrimethamine (Pyr) were investigated density functional theory (DFT) method associated with three levels viz., B3LYP, MN15 wB97XD 6-311++G(d,p) def2TZVPP as basis sets, respectively in Gaussian 16 programs. 1H 13C NMR chemical shifts calculated a gauge-independent atomic orbital (GIAO) approach also applying same sets. All compared theoretical data. Although revealed high degrees correlation between values for using methods. Furthermore, natural charges, energy band gap reactivity determined, while frontier (FMO) electrostatic potential (MEP) surfaces plotted to nature title molecule.