Density functional theory and phytochemical study of Pistagremic acid

作者：Ullah Habib^*; Rauf Abdur; Ullah Zakir; Fazl i Sattar; Anwar Muhammad; Shah Anwar ul Haq Ali; Uddin Ghias; Ayub Khurshid

来源：Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy , 2014, 118: 210-214.

DOI：10.1016/j.saa.2013.08.099

• Density functional theory
• TD-DFT
• B3LYP/6-31G (d, p)
• I.R
• HOMO-LUMO
• Pistagremic acid

We report here for the first time a comparative theoretical and experimental study of Pistagremic acid (P.A). We have developed a theoretical model for obtaining the electronic and spectroscopic properties of P.A. The simulated data showed nice correlation with the experimental data. The geometric and electronic properties were simulated at B3LYP/6-31 G (d, p) level of density functional theory (DFT). The optimized geometric parameters of P.A were found consistent with those from X-ray crystal structure. Differences of about 0.01 and 0.15 angstrom in bond length and 0.19-1.30 degrees degree in the angles, respectively; were observed between the experimental and theoretical data. The theoretical vibrational bands of P.A were found to correlate with the experimental IR spectrum after a common scaling factor of 0.963. The experimental and predicted UV-Vis spectra (at B3LYP/6-31+G (d, p)) have 36 nm differences. This difference from experimental results is because of the condensed phase nature of P.A. Electronic properties such as Ionization Potential (I.P), Electron Affinities (E.A), co-efficient of highest occupied molecular orbital (HOMO), co-efficient of lowest unoccupied molecular orbital (LUMO) of P.A were estimated for the first time however, no correlation can be made with experiment. Inter-molecular interaction and its effect on vibrational (IR), electronic and geometric parameters were simulated by using Formic acid as model for hydrogen bonding in P.A.

• 出版日期2014-1-24