Nilgun Ozpozan Kalaycioglu

Experimental and molecular modeling investigation of (E)-N-{2-[(2-hydroxybenzylidene)amino]phenyl}benzenesulfonamide

The Schiff base compound (E)-N-{2-[(2-hydroxybenzylidene)amino]phenyl}benzenesulfonamide has been synthesized and characterized by IR, NMR and Uv-vis spectroscopies, and single-crystal X-ray diffraction technique. In addition, quantum chemical calculations employing density functional theory (DFT) method with the 6–311++G(d,p) basis set were performed to study the molecular, spectroscopic and some electronic structure properties of the title compound, and the results were compared with the experimental findings. There exists a good correlation between experimental and theoretical data. Enol-imine/keto-amine tautomerization mechanism was investigated in the gas phase and in solution phase using the polarizable continuum model (PCM) approximation. The energetic and thermodynamic parameters of the enol-imine → keto-amine transfer process show that the single proton exchange is thermodynamically unfavored both in the gas phase and in solution phase. However, the reverse reaction seems to be feasible with a low barrier height and is supported by negative values in enthalpy and free energy changes both in the gas phase and in solution phase. The solvent effect is found to be sizable with increasing polarity of the solvents for the reverse reaction. The predicted nonlinear optical properties of the compound are found to be much greater than those of urea.

Synthesis and luminescence properties of BaTiO3:RE (RE = Gd3+, Dy3+, Tb3+, Lu3+) phosphors

Gd3+, Dy3+, Tb3+ and Lu3+ doped BaTiO3-based phosphors were synthesized with modified solid-state technique at 1000 °C. The optimization of reaction conditions were carried out by thermogravimetry and differential thermal analysis methods (DTA/TG). The reaction products obtained in an air atmosphere were characterized by X-ray powder diffraction (XRD). Surface and elemental analyses were performed by using an SEM instrument. The excitation and emission spectra were recorded by photoluminescence spectrophotometer (PL). The thermoluminescence (TL) properties of BaTiO3 samples doped with Gd3+, Dy3+, Tb3+ and Lu3+ were investigated.

Measurement and Properties of the Oxide Ionic Conductivity of β- and δ-Phases in the Binary (Bi2O3)1−x (Tb4O7) x System

The total conductivity (σT) in the β-phase and δ-Bi2O3 doped with Tb4O7 system was measured in the composition range between 1 and 30 mol% Tb4O7 at different temperatures. According to the DTA/TG results, this tetragonal type solid solution was stable up to about ∼740°C, and the solubility limit was found at ∼5 mol% Tb4O7 in the β-phase; this fcc type solid solution was stable up to about ∼740°C, and the solubility limit was found at ∼30 mol% Tb4O7 in the δ-phase. All phases showed predominant oxide ionic conduction. It has been proposed that β- and δ-Bi2O3 phases contain a large number of oxide anion vacancies and incorporated terbium cations at tetrahedral sites that affect the oxygen sublattice of the crystal structure.

MgAl2Si2O8:Mn4+ Systems Doped with Co-Activator for Optoelectronic Applications

Mn4+ doped and Pr3+,4+, Sm3+, Gd3+, Tb3+,4+, Ho3+, Er3+, Tm3+ and Yb3+ co-doped MgAl2Si2O8-based phosphors were prepared by conventional solid state synthesis at 1300 °C. They were characterized by thermogravimetry (TG), differential thermal analysis (DTA), X-ray powder diffraction (XRD), photoluminescence (PL) and scanning electron microscopy (SEM). The luminescence mechanism of the phosphors, which showed broad red emission bands in the range of 600-715 nm and had a different maximum intensity when activated by UV illumination, was discussed. Such a red emission can be attributed to the intrinsic 2E→4A2 transitions of Mn4+.

Synthesis of imine and reduced imine compounds containing aromatic sulfonamide: Use as catalyst for in situ generation of ruthenium catalysts in transfer hydrogenation of acetophenone derivatives

Three imine and three reduced imine ligands containing aromatic sulfonamide (2-7) were isolated by a simple method and characterized by FT-IR, NMR, and elemental analysis. Meanwhile, the interaction of 2-7 ligands with [(p-cymene)RuCl2]2 was analyzed in situ by UV-vis spectrophotometer. The in situ generated catalytic system derived from N-(2-(benzylideneamino)phenyl)-2,4,6-trimethyl-benzenesulfonamides and N-(2-(benzylamino)phenyl)-2,4,6-trimethyl-benzenesulfonamides with [(p-cymene)RuCl2]2 was used as a catalyst in the transfer hydrogenation (TH) of p-substituted acetophenone derivatives. The catalytic systems displayed high activities, which increased in the order 7<4<5<6<1<2<3. The best activity for the TH of 4-chloroacetophenone was provided with the [(p-cymene)RuCl2]2/ligand (3) catalytic system (turnover frequency values: 720 h(-1) for 10 min on S/C: 500/1).

Comparison of MgAl 2 Si 2 O 8 :Mn 4+ systems doped with co-activator ions in terms of long lifetime for optoelectronic applications

Mn⁴⁺ doped and Pr^3+,4+, Sm³⁺, Gd³⁺, Tb^3+,4+, Ho³⁺, Er³⁺, Tm³⁺ and Yb³⁺ co-doped MgAl₂Si₂O₈-based phosphors were prepared by conventional solid state synthesis at 1300 °C. They were characterized by thermogravimetry (TG), differential thermal analysis (DTA), X-ray powder diffraction (XRD), photoluminescence (PL) and scanning electron microscopy (SEM). The luminescence mechanism of the phosphors, which showed broad red emission bands in the range of 600-715 nm and had a different maximum intensity when activated by UV illumination, was discussed. Such a red emission can be attributed to the intrinsic ²E→⁴A₂ transitions of Mn⁴⁺.