Conformational Analysis and Ab-initio, DFT Studies of Vibrational Frequencies and Modes of Phenazopyridine Molecule
In this study, theoretical conformation analysis of Phenazopyridine molecule, has been performed and stable conformations of the molecule were determined. The vibrational spectra of each conformer of the molecule under investigation were calculated and compared with those of experimental IR ve Raman spectra of the molecule in solid phase. The stable conformers of free Phenazopyridine, have been determined using the Ab-initio methods including Density Functional Theory (DFT) with 6-31G, 6-31G(d), 6-31G++(d,p), 6-311g++(d,p) basia sets. The geometrical parameters for the stable conformers were obtained by means of geometry optimization carried out at DFT/B3LYP/6-311G++(d,p) level of theory. For the most stable conformer harmonic and anharmonic vibrational wavenumbers, for the second most stable conformer harmonic vibrational wavenumbers and IR intensities were calculated at the same theory level used in geometry optimization. To characterize the fundamentals, the total energy distrubition (TED) calculations of the vibrational modes were done by using Parallel Quantum Mechanic Solution Program (PQS). The Infrared spectra and Raman spectra of this molecule in solid phase have been measured. To fit the calculated wavenumbers to experimental ones dual scale factors proposed in literature were used. All theoretical values were compared with the experimental results.