Study on molecular structure, spectroscopic investigation (IR, Raman and NMR), vibrational assignments and HOMO–LUMO analysis of L-sodium folinate using DFT: A combined experimental and quantum chemical approach

• Conformers of L-sodium folinate have been analyzed.
• IR, Raman, NMR spectra of L-sodium folinate have been recorded and analyzed.
• The computed vibrational wavenumbers and chemical shifts were seen to be in good agreement with the experimental data.
• Potential energy distribution of the normal modes of the vibrations has been done.
• Mulliken atomic charges and HOMO–LUMO were performed.

In the present work, an exhaustive conformational search of N-[4-[[(2-Amino-5-formyl-(6S)-3,4,5,6,7,8-hexahydro-4-oxo-6-pteridinyl)methyl]amino]benzoyl]-L-glutamic acid disodium salt (L-SF) has been preformed. The optimized structure of the molecule, vibrational frequencies and NMR spectra studies have been calculated by density functional theory (DFT) using B3LYP method with the 6-311++G (d, p) basis set. IR and FT-Raman spectra for L-SF have been recorded in the region of 400–4000 cm−1 and 100–3500 cm−1, respectively. 13C and 1H NMR spectra were recorded and 13C and 1H nuclear magnetic resonance chemical shifts of the molecule were calculated based on the gauge-independent atomic orbital (GIAO) method. Finally all of the calculation results were applied to simulate IR, Raman, 1H NMR and 13C NMR spectrum of the title compound which showed excellent agreement with observed spectrum. Furthermore, reliable vibrational assignments which have been made on the basis of potential energy distribution (PED) and characteristic vibratinonal absorption bands of the title compound in IR and Raman have been figured out. HOMO–LUMO energy and Mulliken atomic charges have been evaluated, either.

In the present work, the experimental and theoretical studies on the structure, vibrations, NMR of L-sodium folinate are presented. The molecular geometry, harmonic vibrational frequencies and NMR spectra of the title compound have been calculated by using the density functional method B3LYP at 6-311++G (d, p) level. Potential energy distribution of the normal modes of the vibrations was done using VEDA program. Finally all of the calculation results were applied to simulate IR, Raman, 1H NMR and 13C NMR spectrum of the L-sodium folinate which show excellent agreement with observed spectrum. All results indicated that B3LYP method was able to provide a satisfactory way for the structural identification of organic compounds.Figure optionsDownload as PowerPoint slide