Gulsiye Ozturk

Crystal Structure and Conformational Analysis of 4-[(p-N,N-Dimethylamino) benzylidene]-2-(3,5-dinitrophenyl)oxazole-5-one

ABSTRACT An azlactone derivative, 4-[(p-N,N-dimethylamino)benzylidene]-2-(3,5-dinitrophenyl)oxazol-5-one (DNPO), C18H14N4O6, has been synthesized, and its crystal structure has been investigated by single crystal X-ray analysis and ab initio method. DNPO is monoclinic, with a = 9.3628(4) Å, b = 13.5148(9) Å, c = 13.7701(6) Å, β = 92.921(4)°, Z = 4, Dx = 1.46 g/cm3, μ(MoKα) = 0.112 mm−1, and space group P 121/c1. The whole molecule is almost planar. The crystal structure is stabilized by C–H · · · N type intramolecular, C–H · · · O type intermolecular interactions. To determine the flexibility of DNPO, the selected torsion angle is varied from − 180° to 180° in steps of 10°, and the molecular energy profile is calculated and analyzed.

Photophysical and Complexation Properties of Benzenesulfonamide Derivatives with Different Donor and Acceptor Moieties

Pyrrolobenzosulfonamide, indolobenzosulfonamide and carbazolobenzosulfonamide derivatives with different acceptor groups were synthesized and their photophysical properties were compared. The electron donor linking sites are found to influence the emission characteristics of these compounds while acceptor linking sites have no noticeable effects on the spectral properties. P2-A5 which is a C–C linked pyrrole derivative exhibited different spectral properties from the C–N linked pyrrole derivatives. The complexation properties of the molecules were also investigated employing Na (I), Ca (II), Li (I), Mg (II), Zn (II) and Cu (II) ions.

Optical Determination of Glucose with Glucose Oxidase Immobilized in PVC together with Fluorescent Oxazol‐5‐One Derivatives

Abstract Fully reversible biosensors for glucose monitoring based on solid polyvinylchloride (PVC) films where the enzyme glucose oxidase (GOx) was incorporated together with 2‐phenyl‐4‐[4‐(1,4,7,10‐tetraoxa‐13‐azacyclopentadecyl)benzylidene]‐5‐oxazolone (CPO‐1), 2‐(3,5‐dinitrophenyl)‐4‐[4‐(1,4,7,10‐tetraoxa‐13‐azacyclopentadecyl)benzylidene]‐5‐oxazolone (CPO‐2), 2‐(4‐nitrophenyl)‐4‐[4‐(1,4,7,10‐tetraoxa‐13‐azacyclopentadecyl)benzylidene]‐5‐oxazolone (CPO‐3) and 2‐(4‐tolyl)‐4‐[4‐(1,4,7,10‐tetraoxa‐13‐azacyclopentadecyl)benzylidene]‐5‐oxazolone (CPO‐4) derivatives have been developed. The limit of detection (LOD) values for glucose were found to be 1.47×10−5 M, 2.01×10−5 M, 0.89×10−5 M, and 0.12×10−5 M for CPO‐1, CPO‐2, CPO‐3, and CPO‐4, respectively (n=7). Sensor films were found to have excellent photostability.

Tuning Photoinduced Intramolecular Electron Transfer by Electron Accepting and Donating Substituents in Oxazolones

The solvatochromic and spectral properties of oxazolone derivatives in various solvents were reported. Fluorescence spectra clearly showed positive and negative solvatochromism depending on substituents. The solvatochromic plots and quantum chemical computations at DFT-B3LYP/6-31 + G(d,p) level were used to assess dipole moment changes between the ground and the first excited singlet-states. The electron accepting nitro substituent at the para-position increased the π-electron mobility, however, the 3,5-dinitro substituent decreased the π-electron mobility as a result of inverse accumulation of the electronic density as compared with that of its ground state. Experimental and computational studies proved that the photoinduced intramolecular electron transfer (PIET) is responsible for the observed solvatochromic effects. We demonstrate that PIET can be finely tailored by the position of the electron accepting and donating substituents in the phenyl ring of the oxazolone derivatives. We propose that the photoactive CPO derivatives are new molecular class of conjugated push-pull structures using azlactone moiety as the π-conjugated linker and may find applications in photovoltaic cells and light emitting diodes.

Structural and photophysical characterization, topological and conformational analysis of 2-o-tolyl-4-(3-N,N-dimethylaminophenyl-methylene)-oxazol-5-one

A novel oxazole-5-one derivative 2-o-tolyl-4-(3-N,N-dimethylaminophenylmethylene)-oxazol-5-one (TDPO) C19H18N2O2 is synthesized and characterized and the crystal structure is determined by X-ray crystallography. TDPO is monoclinic in the P21/c space group. The molecule adopts the Z configuration. To enlighten the flexibility of TDPO, the selected torsion angle is varied from −180° to 180° in each 10° separately, and the molecular energy profile is calculated and analyzed by density functional calculations. In addition, Bader’s QTAIM analysis is performed to investigate the intramolecular weak interactions.

Design and application of a sol-gel based fluorescent glucose arrays

Here we present a new sol-gel based fluorescent glukoz biosensor. The sensor is based on the pH sensitive fluorescent dye entrapped in a tetraethoxysilane (TEOS) based sol-gel together with glukoz oxidase. Micro-analytic sustem which can measure the pH induced chance in the fluorescens intensity due to the enzymatic reaction in spotted layer on the glass surface was used as a measuring system. The system was calibrated to glukoz. As well as characterization, glukoz biosensing in such fruit juice samples were carried out.