O. Unsalan

Structural conformations and vibrational spectral study of chloroflavone with density functional theoretical simulations.

NIR-FT Raman and FT-IR spectra of 6-chloroflavone were recorded and analyzed. The vibrational wavenumber of the compound have been computed using B3LYP/6-31++G(d,p) level to derive the equilibrium geometry, conformational stability, molecular orbital energies and vibrational wavenumbers. The carbonyl stretching vibrations have been lowered due to conjugation and hydrogen bonding in the molecules. The assignment of fundamental vibrations agrees well with the calculated wavenumbers.

Trans- and cis-stilbene isolated in cryogenic argon and xenon matrices.

Monomers of trans- (TS) and cis-stilbene (CS) were isolated in cryogenic argon and xenon matrices, and their infrared (IR) spectra were fully assigned and interpreted. The interpretation of the vibrational spectra received support from theoretical calculations undertaken at the DFT(B3LYP)/6-311++G(d,p) level of theory. In situ broadband UV irradiation of the matrix-isolated CS led to its isomerization to TS, which appeared in the photolysed matrices in both non-planar and planar configurations. The non-planar species was found to convert into the more stable planar form upon subsequent annealing of the matrices at higher temperature. TS was found to be photostable under the used experimental conditions. The structure of the non-planar TS form was assigned based on the comparison of its observed IR spectrum with those theoretically predicted for different conformations of TS. Chemometrics was used to make this assignment. Additional reasoning on the structure of the studied stilbenes is presented taking as basis results of the Natural Bond Orbital analysis.

FTIR spectroscopic and quantum chemical studies on hydantoin

In this study the geometry optimization of monomeric and dimeric forms (D1, D2, and D3) of hydantoin molecule were done using DFT method employing 6–31++G(d, p) basis set. Harmonic and anharmonic wavenumbers and infrared intensities were computed at the same theory level. Experimental IR spectrum was recorded in the region 400–4000 cm−1. It has also been characterized by 1H and 13C NMR spectrum. The hydrogen bond (HB) interaction of hydantoin was analyzed via dimers of hydantoin. Detailed vibrational wavenumber shifts and all vibrational mode analyses were reported. Total energy distributions (TED, %) calculations were done to characterize the fundamentals.

Solvent effect on the vibrational spectra of Carvedilol.

Carvedilol (CRV) is an important medicament for heart arrhythmia. The aim of this work was the interpretation of its vibrational spectra with consideration on the solvent effect. Infrared and Raman spectra were recorded in solid state as well in solution. The experimental spectra were evaluated using DFT quantum chemical calculations computing the optimized structure, atomic net charges, vibrational frequencies and force constants. The same calculations were done for the molecule in DMSO and aqueous solutions applying the PCM method. The calculated force constants were scaled to the experimentally observed solid state frequencies. The characters of the vibrational modes were determined by their potential energy distributions. Solvent effects on the molecular properties were interpreted. Based on these results vibrational spectra were simulated.

Vibrational (FT-IR and FT-Raman) spectral investigations of 7-aminoflavone with density functional theoretical simulations

FT-Raman and FT-IR spectra of the 7-aminoflavone have been recorded and analysed. The detailed interpretation of the vibrational spectra has been carried out with the aid of normal coordinate analysis following the scaled quantum mechanical force field methodology. The various intramolecular interactions that are responsible for stabilisation of the molecule were revealed by natural bond orbital analysis. The obtained vibrational wavenumbers and optimised geometric parameters were observed to be in good agreement with the experimental data. The carbonyl stretching vibrations have been lowered due to conjugation and hydrogen bonding in the molecules.

Effects of hazardous pollutants on the walls of Valence Aqueduct (Istanbul) by Raman spectroscopy, SEM-EDX and Geographical Information System.

This study involves Raman spectroscopic (176-2900cm(-1)), SEM-EDX and Geographical Information System studies of the pollutants on the walls of Valence Aqueduct (Bozdoğan Kemeri), Istanbul, Turkey. Raman spectroscopy is a useful analytical method in characterization of painting materials and corrosion products. Especially, when it is not possible to take the samples from the place they exist, handheld Raman spectrometers play an important role to identify the materials in these samples. Furthermore, more information could be gathered when it is combined with SEM-EDX studies. On the other hand, regarding the cultural heritage, it is crucial to determine precise coordinates of the historical peninsula and the samples which have been exposed to pollutants, by Geographical Information Systems in order to study them and take precautions for the future. Handheld Raman spectrometer (NanoRam by B&WTek) allows recording of acceptable and good quality spectra of a large majority of minerals outdoors. Raman spectra of minerals and pollutants in this study were obtained using 785nm laser excitation source. Observed Raman bands are found at correct wavenumber positions within ±3cm(-1) compared to reference values in the literature. Taking into account the resolution of the spectrometer (9cm(-1)), the results are still reliable and applicable on such systems. Areas of potential applications of these instruments include all kind of common geoscience work outdoors.

Micro-Raman, Mid-IR, Far-IR and DFT studies on 2-[4-(4-Fluorobenzamido)phenyl]benzothiazole

Molecular structure of 2-[4-(4-Fluorobenzamido)phenyl]benzothiazole was determined by quantum chemical calculations. MidIR and FarIR spectra were recorded at room temperature, with 4 cm(-1) resolution in the 4000-400 cm(-1) and 700-30 cm(-1) regions, respectively for the first time. Raman spectrum was recorded in the 4000-100 cm(-1) range. Optimized molecular structure and vibrational wavenumbers of the compound in its ground state have been calculated by using Density Functional Theory using B3LYP functional with 6-311++G(d,p) basis set. Vibrational wavenumbers were seen to be in good agreement with the experimental IR data. Furthermore, assignments of each vibrational mode were interpreted in terms of potential energy distributions in detail.

Kütüphanelerdeki El Yazması Eserlere Yönelik Bir Belgeleme Önerisi: İstanbul Üniversitesi Edebiyat Fakültesi Nadir Eserler Kitaplığı Örneği

Libraries are important institutions which transferred unique cultural heritage from past to present. The role of conservation works is essential in transmitting of the books, manuscripts and documents which reflect near past to the next generations in a healthy way. Bringing into the ideal levels of indoor comfort (climatic) conditions is one of the protection studies in the library environments. Temperature, relative humidity, light, radiation, dust, vibration; microbiological activity, biological factors: insects and rodents, intentional / unintentional acts of human-induced factors and disaster factors affect library buildings and collections. The collections which have their vulnerable chemical structure nature are faced with a very quick deterioration or extinction. Due to the all of these reasons, necessary precautions should be taken by measurement, assessment and continuous monitoring of the library materials for indoor environment before any kind of deterioration. In this study, proposal of solution based on Geographic Information Systems (GIS) and Raman Spectroscopic Analysis, which provides fast data analysis for the diagnosis of deterioration occurring over time, has been proposed. It is aimed that deterioration in the manuscripts in the libraries depending on the ambient conditions, by using digital and optical imaging such as Raman Spectroscopy method, GIS and to collect a database of these records for the future studies. Using of data obtained from this study as base in the diagnosis and restoration works and as tool in development of conservation policies are emphasized. Spectroscopic analysis were performed by Raman spectroscopic techniques. According to the Raman spectroscopy results, it was determined that pigments were used for manuscripts. On the other hand, deterioration levels were defined by GIS with high precision.

FTIR spectroscopic and quantum-chemical studies on some tribromoindenes and their isomers

Combined experimental and computational studies on molecular structure of newly synthesised transtirans 1,2,3-tribromo-1,2,3-trihydro-1H-benz[f]indene (TTTBI) were reported. Also, only computational studies were done for cis-trans-1,2,3-tribromo-1,2,3-trihydro-1H-benz[f]indene (CTTBI) and cis-cis-1,2,3-tribromo-1,2,3-trihydro-1H-benz[f]indene (CCTBI) in order to understand the vibrational spectra and molecular parameters of them. The geometry optimization and vibrational wave numbers of the title molecules were carried out with the Gaussian98 program package by using Hartree-Fock (HF) and Density Functional Theory (DFT) with B3LYP functional and 6–31G (d) basis set. All calculations were done for the title compounds in their ground states. Especially for CTTBI and CCTBI, which could not be synthesized yet, these kind of pre-calculations take an important role for their synthesis process. Also crystal structural parameters of TTTBI by single-crystal X-ray diffraction method was used as input for computational study of it. Observed and calculated vibrational wave numbers were compared. Because the use of benz[f]indene as a cyclopentadienyl ligand attracted much attention because an annulated benzo ring might increase both the stereocontrol and productivity of catalytic system, TTTBI and other computationally studied and modeled two molecules may play an important role of other types of compounds as a starting structures.