title: Spectroscopic and quantum chemical study of an alkaloid aristolochic acid I.
abstract: Aristolochic acids (AAs) (Aristolochiaceae) are used in the traditional Chinese herb medicine. We have presented the geometry optimization, electrostatic potential surface, frontier orbital energy gap and vibrational wavenumbers of aristolochic acid I (AA I) using ab initio Hartree-Fock (HF) and density functional theory (DFT/B3LYP) method employing 6-311G(d,p) basis set. A complete vibrational assignment has been done on the basis of calculations on monomer and dimer of AA I. The UV-vis absorption spectrum has been recorded in ethanol solvent and compared with the calculated one in the gas phase as well as in solvent environment (integral-equation formalism polarizable continuum model; IEF-PCM) using TD-DFT/6-31G basis set. A short outline of the NBO analysis segment with their structural meaning has been presented. The variation of thermodynamic properties with temperature was calculated theoretically and the thermal response of the compound has been recorded with the help of differential scanning calorimetry (DSC) in N2 environment.
authors: Department of Physics, University of Lucknow, Lucknow 226007, India; Department of Physics, Siddhanath Sc. Campus, Tribhuvan University, Nepal.
authors: Bhawani Datt
authors: BD
authors: Joshi
authors: Anubha
authors: A
authors: Srivastava
authors: Vineet
authors: V
authors: Gupta
authors: Poonam
authors: P
authors: Tandon
authors: Sudha
authors: S
authors: Jain
mesh_terms: D000470:Alkaloids / Q000737:chemistry*; D029065:Aristolochiaceae / Q000737:chemistry*; D034341:Aristolochic Acids / Q000737:chemistry*; D008958:Models, Molecular; D011789:Quantum Theory; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared; D013059:Spectrum Analysis, Raman
chemical_list: D000470:Alkaloids; D034341:Aristolochic Acids; C000228:aristolochic acid I
keywords: AA I; Ab initio and DFT; IR; NBO; Raman; UV–vis spectroscopy