Browsing by Author "Yurdakul S."

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DFT, FT-IR and FT-Raman investigations of 1-methyl-2- imidazolecarboxaldehyde
(2013-10-01) Polat T.; Yurdakul S.
The FT-IR and FT-Raman spectra of 1-methyl-2-imidazolecarboxaldehyde were recorded in the region 4000-400 cm-1 and 3500-50 cm-1, respectively. Optimized geometric parameters, conformational equilibria, normal mode frequencies, and corresponding vibrational assignments of title molecule were examined by means of density functional theory (DFT) method with B3LYP/6-311++G(d,p) basis set. All vibrational frequencies were assigned in detail with the help of total energy distribution (TEDs). The results showed that the DFT/B3LYP method predics vibrational frequencies and the structural parameters effectively. Furthermore, solvent effects are investigated in different solvents (chloroform, dimethylsulfoxide and water) using the self-consistent isodensity polarizable continuum model (SCI-PCM). All results indicate that the combination of SCI-PCM model and DFT/B3LYP/6-311++G(d,p) calculation could give excellent explanations of the solvent effects. Intermolecular hydrogen bonding between 1-methyl-2-imidazolecarboxaldehyde and water was investigated using quantum chemical methods. DFT calculations were used to optimize the adducts of heterocycle with the single water molecule. © 2013 Elsevier B.V. All rights reserved.
Quantum chemical and spectroscopic (FT-IR and FT-Raman) investigations of 3-methyl-3h-imidazole-4-carbaldehyde
(2014-12-10) Polat T.; Yurdakul S.
FT-IR and FT-Raman spectra of 3-methyl-3h-imidazole-4-carbaldehyde (3M3HI4C) were recorded in the region 4000-400 cm-1 and 3500-50 cm-1, respectively. Optimized geometric parameters, conformational equilibria, normal mode frequencies, and corresponding vibrational assignments of 3M3HI4C were theoretically examined by quantum chemical methods for the first time. All vibrational frequencies were assigned in detail with the help of total energy distribution (TEDs). The experimental wavenumbers were compared with the scaled vibrational frequencies determined by DFT/B3LYP method. The results showed that the B3LYP/6-311++G(d,p) method predicts vibrational frequencies and the structural parameters effectively. The most stable conformer of the title compound was determined. The total electron density and molecular electrostatic potential surfaces of the molecule were constructed by using B3LYP/6-311++G(d,p) method to display electrostatic potential (electron + nuclei) distribution. The electronic properties HOMO and LUMO energies were measured. The lower energy band was assigned to the HOMO → LUMO transition. Natural bond orbital analysis of title molecule has been performed to indicate the presence of intramolecular charge transfer. Energies, relative stabilities, and dipole moments of title molecule were also compared and analyzed in the gas phase and in solvents. Furthermore, solvent effects on the geometry and vibrational frequency of 3M3HI4C were studied theoretically at the DFT/B3LYP level in combination with the conductor polarizable continuum model (C-PCM). © 2014 Elsevier B.V. All rights reserved.