Density functional theory and phytochemical study of 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 Å in bond length and 0.19-1.30° 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.
Institute of Chemical Sciences, University of Peshawar, 25120 Peshawar, Pakistan. Electronic address: habib_chemist@yahoo.com.
Habib
H
Ullah
Abdur
A
Rauf
Zakir
Z
Ullah
Fazl-i-Sattar
Muhammad
M
Anwar
Anwar-ul-Haq Ali
AU
Shah
Ghias
G
Uddin
Khurshid
K
Ayub
D003198:Computer Simulation; D018360:Crystallography, X-Ray; D004583:Electrons; D008958:Models, Molecular; D008968:Molecular Conformation; D064209:Phytochemicals / Q000737:chemistry*; D011789:Quantum Theory; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared; D014315:Triterpenes / Q000737:chemistry*
D064209:Phytochemicals; D014315:Triterpenes; C581170:pistagremic acid
B3LYP/6-31G (d, p); Density functional theory; HOMO–LUMO; I.R; Pistagremic acid; TD-DFT