Structural Geometry, Vibrational and Electronic Spectra Investigation on Naringin Molecule Using Experimental and Density Functional Calculations

Abstract

In the present investigation we investigate the structural, spectral and Molecular Orbitals (MO's) properties of Naringin compound. It is a bioflavonoid, present in the fruits; it is responsible for bitter taste in fruits. The Naringin has a flavanone-7-O-glycoside between the flavanone naringenin and the disaccharide neohesperidose. It consists of naringenin (ring A-C), D-glucose (ring D) and L-rhamnose (ring E). Our aim is to predict the molecular structure and investigate the insights of the Naringin molecule. Besides that to study the vibrational behavior of Naringin, the FT-IR and FT-Raman spectra were recorded in the ranges of 4000-400cm-1 and 3500-50cm-1 respectively, and to study the frontier molecular orbitals, the UV-Visible spectrum was recorded in the range of 500-200nm. In addition to that the geometry of Naringin molecular structure was optimized by Density Functional Theory (DFT/B3LYP) calculation using 6-31g (d, p) level of basis set. For the optimized structure, vibrational spectral calculation was performed by the same level of theory calculation, furthermore, interpreted the calculated spectra of Naringin in terms of TED analysis. Moreover, to explain the inter and intra molecular charge transfer within the molecule the Natural Bond Orbital analysis (NBO) was performed, NBO analysis gave us a clear picture about hyperconjugative interaction energy between the donor (i) and acceptor(j) bond orbitals. In addition to that, the first order hyperpolarizability (β0), polarizability (α) and dipole moment (μ) of Naringin was computed. The frontier MO's (HOMO-LUMO) of Naringin was analyzed by TD-B3LYP/6-31g (d, p) level of basis set. Finally, the experimentally recorded results were compared with computed values, the agreement and discrepancies were studied carefully.