P. NISHAD*, A.K. DWIVEDI**, A. TIWARI*, A.K. PANDEY*, S.N. TIWARI*, G. MISHRA*, D.D. DUBEY*, V. SINGH***, S.I. ANSARI****, V.N. MISHRA****#
*Department of Physics, “K.S. Saket” P.G. College, Ayodhya (UP), India
**Department of Chemistry, “Kisan” College Sohsarai, Biharsharif Nalanda, Bihar, India
***Department of Physics, College of Natural and Mathematical Sciences, University of Dodoma, Dodoma 259, Tanzania
****Department of Physics, “Shri Ramswaroop” Memorial college of Engineering & Management, Lucknow (UP), India, #e-mail: vnvictorious@gmail.com
In present communication geometry optimization vibrational analysis of thalidomide (molecule A) and its methyl isomer (molecule B) has been carried out by density functional theory with the B3LYP hybrid functional and a comprehensive 6-311+G(d,p) basis set. The computed bond length and angle of glutarimide’s ring in molecule B are changed due to electron withdrawing methyl group substitution. The vibrational assignments of both molecules A and B are made by using animated Gauss View with high order accuracy. The electronic properties and chemical reactivity descriptor like absolute electronegativity (χ), ionization potential (µ), chemical hardness (ɳ), chemical softness (S) of molecules A and B are computed by highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO). The computed energy gap (HOMO-LUMO) of molecule B is more reactive than molecule A. The Fukui function (FF) of molecules A and B are computed by Mullikan’s charge on atoms and quantitatively computed most electrophilic charge center and nucleophilic charge center however molecular electrostatic potential surface qualitatively predict same results. The natural bond orbital analysis highlights a strong stabilizing charge transfer from the nitrogen lone pair to the antibonding pi orbital (Lp(1)N6 → π*(O1-C10))Of the carbonyl group. This interaction provides stabilization energies of 50.60 kcal/mol for thalidomide and 51.02 kcal/mol for its isomer. The biological activities of both molecules A and B are computed by Prediction of Activity Spectra for Substances (PASS) online server. The docking of molecules A and B by P2X7 protein are performed by using SWISS dock online server.
Key words: Density functional theory (DFT), HOMO, LUMO, PASS, docking.
Corresponding author’s e-mail: vnvictorious@gmail.com