Probing the non-bonding interaction of small molecules with graphene oxide using DFT based vibrational circular dichroism

Abstract

This study explores the non-bonding interaction of graphene oxide with small molecules such as NO2, SO3, SO2, and CO2 by density functional theory-based vibrational circular dichroism (VCD) and Raman spectroscopies. Molecular dynamics (MD) simulation is used to generate all possible and stable cluster conformers of the GO and small molecules. The non-bonding interactions between GO and small molecules in the gas phase are calculated with the help of density functional theory (DFT). VCD and Raman spectra are computed using ωB97XD/6-31G+(d) level of theory. Vibrational mode of the O–H wagging, C–H twisting, O–H bending, C–H bending, C–H rocking, C–H stretching, O–H stretching demonstrate representative VCD signature band in the gas phase. The highest and the lowest VCD signal are noticed for GO-NO2 and GO-CO2 complex, respectively. The most intense negative VCD signal is observed for GO-NO2, and GO-CO2 complexes, whereas the most intense positive VCD signal, is detected for GO-SO3 and GO-SO2 complexes. Non-bonding interaction of GO with NO2, SO3, SO2, and CO2 influences the various vibrational modes in the conformers, thus significantly changing the VCD signals. However, the Raman signal shows no significant changes for the non-bonding interaction examined in the multiple conformers. These findings indicate that vibrational circular dichroism may be employed for detecting the non-bonding interactions of graphene oxide with small molecules.