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FT-IR and Raman spectroscopic and quantum chemical investigations of some metal halide complexes of 1-phenylpiperazine

New metal halide complexes in the form of M(pp)(2)Cl(2) (where pp=1-phenylpiperazine and M=Pd or Hg) have been prepared for the first time and their FT-IR and FT-Raman spectra are reported in the region of 4000-10 cm(-1) and 4000-50 cm(-1), respectively. The optimized geometric parameters, normal mode frequencies and corresponding vibrational assignments of the present compounds are theoretically examined by means of B3LYP hybrid density functional theory (DFT) method together with Lanl2dz basis set. Furthermore, reliable vibrational assignments made on the basis of potential energy distribution (PED) were calculated and the thermodynamics functions, the highest occupied and the lowest unoccupied molecular orbitals (HOMO and LUMO) of these compounds have been predicted. According to the results, theoretical values have been successfully compared against experimental data.

1H, 13C, 15N NMR and nJ(C, H) coupling constants investigation of 3-piperidino-propylamine: A combined experimental and theoretical study

Proton coupled and decoupled (13)C, (1)H, (15)N, DEPT, COSY, HETCOR and INADEQUATE NMR spectra of 3-piperidino-propylamine (3-pipa) have been reported for the first time. In order to provide a precise structural elucidation, the magnitude of (n)J(C, H) (n=1, 2, 3) coupling constants of 3-pipa (C(8)H(18)N(2)) have been determined. Solvent effects on chemical shifts have been investigated by using CDCl(3) and DMSO. Molecular mobility of the title molecule has also been investigated by performing (13)C NMR spin-lattice relaxation time (T(1)) measurements. (13)C, (1)H and (15)N NMR chemical shifts and (1-3)J(C, H) coupling constants of 3-pipa have been calculated by means of B3LYP density functional method with 6-311++G(d,p) basis set. Comparison between the experimental and the theoretical results indicates that density functional B3LYP method is able to provide satisfactory results for predicting NMR properties.

4-Mercaptophenylboronic acid: Conformation, FT-IR, Raman, OH stretching and theoretical studies

4-Mercaptophenylboronic acid (4-mpba, C6H7BO2S) was investigated experimentally by vibrational spectroscopy. The molecular structure and spectroscopic parameters were studied by computational methods. The molecular dimer was investigated for intermolecular hydrogen bonding. Potential energy distribution analysis of normal modes was performed to identify characteristic frequencies. The present work provides a simple physical picture of the OH stretch vibrational spectra of 4-mpba and analogues of the compound studied. When the different computational methods are compared, there is a strong evidence of the better performance of the BLYP functional than the popular B3LYP functional to describe hydrogen bonding in the dimer. The findings of this research work should be useful to experimentalists in their quests for functionalised 4-mpba derivatives.

Vibrational spectroscopic investigation of 1-pyrrolidino-1-cyclohexene: A comparative density functional study

Infrared and Raman spectra of 1-pyrrolidino-1-cyclohexene (1pych) have experimentally been reported in the region of 4000-100 cm(-1). The conformational analysis, optimized geometric parameters, normal mode frequencies and corresponding vibrational assignments of 1pych (C10H17N) have theoretically been examined by means of the Becke-3-Lee-Yang-Parr (B3-LYP) density functional theory (DFT) method together with the 6-31++G(d,p) basis set. Furthermore, reliable vibrational assignments have been made the basis of potential energy distribution (PED) and the thermodynamics functions, highest occupied and lowest unoccupied molecular orbitals (HOMO and LUMO) of 1pych have been predicted. Angular distribution of the probability density of populations of its conformational isomers is determined by analysis of the potential energy surface (PES). Comparison between the experimental and theoretical results indicates that B3-LYP method is provides satisfactory results for the prediction vibrational wavenumbers and structural parameters and the mixture of envelope and twist conformers is supposed to be the most stable form of 1pych.

Vibrational Spectroscopic Investigation and Conformational Analysis of Methacrylamidoantipyrine: A Comparative Density Functional Study

FT-IR and Raman spectra of methacrylamidoantipyrine (MAAP) have been reported in the region of 4000–10 cm−1 and 4000–100 cm−1, respectively. The optimized geometric parameters, conformational analysis, normal mode frequencies, and corresponding vibrational assignments of MAAP (C15H17N3O2) have been examined by means of density functional theory (DFT) method using the Becke-3-Lee-Yang-Parr (B3LYP) exchange-correlation functional and the 6-31G

The investigation of the effect of thermal treatment on bentonites from Turkey with Fourier transform infrared and solid state nuclear magnetic resonance spectroscopic methods.

There is a great deal of interest in the building industry in burned clays for production of building materials. Therefore, the effect of heat treatment on natural bentonite from Turkey was investigated by Fourier transform infrared (FT-IR) between the region of 4000-400cm(-1) and (29)Si, (27)Al magic angle spinning nuclear magnetic resonance (MAS NMR) measurement techniques at various temperatures between 200 and 700°C for 2h. The structural changes were also investigated upon heat treatment.

Fourier Transform Infrared, Solid-State Nuclear Magnetic Resonance, and X-Ray Diffraction Studies of Natural and Acid-Treated Bentonites from Turkey

ABSTRACT The Fourier transform infrared (FT-IR) technique is widely used to distinguish structural properties and to derive information about structural changes following the chemical modification of clays in different conditions. Natural and acid-treated bentonites with HCl from Turkey were investigated by FT-IR between the region of 4000 and 400 cm−1 and the obtained results were supported by 29Si, 27Al magic angle spinning nuclear magnetic resonance (MAS NMR) and X-ray diffraction (XRD) measurement techniques. Effects of acid treatment were monitored by following the destruction of the original bentonite sample upon the acid treatment with different (6 hr, 12 hr, and 24 hr) acid exposure times. Following 24-hr acid treatment, the tetrahedral Si4+ structure was not fully collapsed but most of it turns into three-dimensional SiO2 impurity.

Vibrational spectroscopic and conformational studies of 1-(4-pyridyl)piperazine

Possible stable conformers of the 1-(4-pyridyl)piperazine (1-4pypp) molecule were experimentally and theoretically studied by FT-IR and Raman spectroscopy. FT-IR and Raman spectra were recorded in the region of 4000–200 cm−1. Optimized geometric structures related to the minimum on the potential energy surface were investigated by the B3LYP hybrid density functional theory method using the 6-31G(d) basis set. Comparison of the experimental and theoretical results indicates that the density functional B3LYP method provides satisfactory results for the prediction of vibrational wavenumbers and structural parameters and equatorial-equatorial (e-e) isomer is supposed to be the most stable form of the 1–4pypp molecule.

Computational study on favipiravir adsorption onto undoped- and silicon-decorated C60 fullerenes

Adsorption and interaction mechanisms of fullerene-based complex systems for possible drug delivery vehicles have been at the center of increasing attention. In the scope of this work, the interaction mechanism between an important antiviral drug favipiravir and silicon-doped/undoped C60 fullerenes have been investigated using density functional theory (DFT). Calculations were carried out in both gas phase and water media to see the possible solvent effects. The effect of adsorption of the favipiravir on the SiC59 fullerene system and the nature of interaction were examined by analyzing the band shifts in the carbonyl stretching vibrations and natural bond orbital (NBO) properties of the examined complexes. Some important structural and electronic properties were reported and discussed as well. It was observed that doping the C60 fullerene nanocages with silicon atom enhanced the adsorption mechanism and calculations performed in water media gave rise to more stable complexes for silicon-doped systems com...

Vibrational spectroscopic study on some Hofmann-Td type clathrates: Ni(4-phenylpyridine)2M(CN)4·2G (M=Cd or Hg, G=1,4-dioxane).

New Hofmann-T(d) type clathrates in the form of Ni(4-Phpy)(2)M(CN)(4)·2G (where 4-Phpy=4-phenylpyridine, M=Cd or Hg and G=1,4-dioxane) have been prepared in powder form and their FT-IR and Raman spectra have been reported. The results suggest that these compounds are similar in structure to the Hofmann-T(d) type clathrates.