Experimental and Computational Analysis of FT-IR, Raman Spectra, and Hydrogen Bonds in L-Ascorbic Acid/Diethyl Sulfoxide System

Interaction between ascorbic acid (AA; Vitamin C) and diethyl sulfoxide (DESO) was experimentally investigated using FTIR and Raman techniques. Characteristics of hydrogen bonds formed between hydrogens of hydroxyl groups in AA and oxygen of DESO were identified by analysis of vibrational frequencies. RHF/6-31++G** and B3LYP/6-31++G** calculations were performed to investigate geometrical parameters of H-bonds and estimate vibrational bands of FTIR and Raman spectra. Quantum calculations were performed for three system configurations according to the number and location of H-bond between two molecules in both gas and liquid phases. Both of vibrational and geometrical calculations exhibited good compatibility with the experimental results and the calculations previously reported for AA and DESO. The new vibrational frequencies assigned to the interactions between AA and DESO and variation of main vibrational frequencies during the interactions between two molecules were also characterized according to the calculations.