Osman Dayan

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, spectroscopic characterization, X-ray structure and DFT studies on 2,6-bis(1-benzyl-1H-benzo[d]imidazol-2-yl)pyridine

The title molecule, 2,6-bis(1-benzyl-1H-benzo[d]imidazol-2-yl)pyridine (C(33)H(25)N(5)), was synthesized and characterized by elemental analysis, FT-IR spectroscopy, one- and two-dimensional NMR spectroscopies, and single-crystal X-ray diffraction. In addition, the molecular geometry, vibrational frequencies and gauge-independent atomic orbital (GIAO) (1)H and (13)C NMR chemical shift values of the title compound in the ground state have been calculated using the density functional theory at the B3LYP/6-311G(d,p) level, and compared with the experimental data. The complete assignments of all vibrational modes were performed by potential energy distributions using VEDA 4 program. The geometrical parameters of the optimized structure are in good agreement with the X-ray crystallographic data, and the theoretical vibrational frequencies and GIAO (1)H and (13)C NMR chemical shifts show good agreement with experimental values. Besides, molecular electrostatic potential (MEP) distribution, frontier molecular orbitals (FMO) and non-linear optical properties of the title compound were investigated by theoretical calculations at the B3LYP/6-311G(d,p) level. The linear polarizabilities and first hyper polarizabilities of the molecule indicate that the compound is a good candidate of nonlinear optical materials. The thermodynamic properties of the compound at different temperatures were calculated, revealing the correlations between standard heat capacity, standard entropy, standard enthalpy changes and temperatures.

Concomitant polymorphism of a pyridine-2,6-dicarboxamide derivative in a single space group: experimental and molecular modeling study.

The title compound, N(2),N(6)-bis{2-[(Z)-2-hydroxybenzylideneamino]phenyl}pyridine-2,6-dicarboxamide (3), has been synthesized by the reaction of 2-{(2-aminophenylimino)methyl}phenol (1) with pyridine-2,6-dicarbonyl dichloride (2), and characterized by elemental analysis, FT-IR and NMR spectroscopies and thermal analysis. Compounds 1 and 3 were evaluated for their antibacterial activities against Gram-positive and Gram-negative bacteria. The catalytic activity of 3 was also studied, and as a result, the in situ prepared three component system Ru(II)/3/KOH is shown to be an efficient catalyst for the transfer hydrogenation reaction of various ketones under mild conditions. Compound 3 has been crystallized in two polymorphic forms under the same conditions, and their crystal structures have been determined using single crystal X-ray diffraction technique. The molecular geometry, vibrational frequencies and gauge-independent atomic orbital (GIAO) (1)H and (13)C NMR chemical shift values of 3 in the ground state have been calculated using the density functional theory (DFT/B3LYP) method with the 6-31G(d) basis set, and compared with the experimental data. The results are in good agreement with experimental data. The effect of different solvents on the geometry, vibrational frequencies, total energies and dipole moments was also studied using the same method by applying the Onsager Model. There are subtle differences in the conformations and packing of the two polymorphs as a consequence of intermolecular hydrogen bonding interactions. Therefore, DFT calculations for the hydrogen bond interactions in the polymorphs were carried out using same basis set. The changes of thermodynamic properties from the monomers to 3 with the temperature ranging from 200 K to 400 K have been obtained using the statistical thermodynamic method.

Synthesis of Tetranuclear Ruthenium (Ii) Complex of Pyridyloxy-Substituted 2,2′-Dioxybiphenyl-Cyclotriphosphazene Platform and its Catalytic Application in the Transfer Hydrogenation of Ketones

GRAPHICAL ABSTRACT Abstract Cyclophosphazene was reacted with biphenyl-2,2’- diol to afford the N3P3Cl4(O2C12H8) (1). Then, pyridyloxy cyclophosphazene, spiro N3P3(O2C12H8)(O‒C5H4N-3)4 (2) was synthesized from the reaction of 3-hydroxy pyridine and compound 1. The reaction of 2 with [RuCl2(p-cymene)]2 afforded Ru(II) complex (3). The structures of the ligand and complex are characterized by elemental analysis, FT-IR, 1H-, and 31P-NMR spectroscopy. Ru(II) complex has been employed as catalysts for the transfer hydrogenation of acetophenone in the presence of KOH using 2-propanol as a hydrogen source. The complex has demonstrated good catalytic activity in transfer hydrogenation of ketones.

COPPER(II) AND COBALT(II) COMPLEXES OF 2,6-DIACETYLPYRIDINE BIS(O-METHYLOXIME): A THEORETICAL INVESTIGATION

AbstactThe molecular geometries and vibrational frequencies of the title compounds in the ground state are calculated using the Hartree-Fock (HF) and density functional theory (DFT/B3LYP) methods with the LANL2DZ basis set and compared with the experimental data. The calculated results show that the optimized geometries can well reproduce the crystal structural parameters, and the theoretical vibrational frequencies show good agreement with the experimental values. The energetic behavior of the title compounds in solvent media is examined using the B3LYP method with the LANL2DZ basis set by applying the Onsager and polarizable continuum model (PCM). In addition, molecular electrostatic potential (MEP) and frontier molecular orbital (FMO) analyses of the title compounds are investigated by theoretical calculations.

Palladium(II) Complexes Containing 2,6-Bis(Imino)Pyridines: Synthesis, Characterization, Thermal Study, and Catalytic Activity in Suzuki Reactions

A series of palladium complexes: [(Pydim)PdCl](PdCl3) (Pydim (1): pyridine-2,6-diimine) have been synthesized from palladium dichloride and the corresponding pydim. The Pd (II) complexes have been used as catalyst in the Suzuki reaction of aryl halides. Moreover, thermal behaviors of palladium complexes have been studied in nitrogen atmosphere using TG/DTG and DTA techniques. The values of activation energy Ea, and reaction order n, the entropy change Δ S*, enthalpy change Δ H#, and Gibbs free energy change Δ G# of the thermal decomposition were calculated by means of several methods based on the single heating rate.

Synthesis and photovoltaic properties of new Ru(II) complexes for dye-sensitized solar cells

Two groups Ru(II) complexes, (1A-C and 2A) (A-C = 2,6-bis(2-benzimidazolyl)pyridines, bbpy, with various substituents at 2-, 5-, and 6-positions) have been prepared and applied for dye–sensitized solar cells (DSSC). The compounds were characterized by various techniques. The optical and electrical properties of sensitizers were investigated with UV–Vis absorption spectroscopy and cyclic voltammetry. High power conversion efficiencies up to 5.16%, have been achieved with 2Ae. Current–voltage characteristics of DSSCs clearly affected by the changing of the ligands at sensitizers. Additionally, computational studies show that locations of frontier molecular orbitals are significantly important for power–conversion efficiencies in DSSCs.

Synthesis and Characterization of Ruthenium(II) Complexes Bearing Benzimidazole Ligands: For Transfer Hydrogenation Catalysis

Ru(II) complexes with the general formula [RuCl2(p-cymene)(L1-3)], K1–3, (L1–3: monodentate benzimidazole ligands), [RuCl2(L5–6)(S)], K4–7, (L5–6: tridentate benzimidazole ligands, S: Solvents [methanol or acetonitrile]), and [RuCl2(L5)(L1–2)], K8–9, were synthesized from [RuCl2(p–cymene)]2 dimer and mono- and tridentate benzimidazole ligands. The compounds were characterized by elemental analysis, IR, UV-Vis, and NMR. The synthesized Ru(II) complexes (K1–9) were tested as catalysts for the transfer hydrogenation (TH) of acetophenone to secondary alcohols in the presence of KOH using 2–propanol as a hydrogen source at 82°C. All complexes were active catalysts for TH of acetophenone with good yields under mild conditions (after 60 minutes, yields of up to 97%).

Bis{2,6-bis[1-(4-fluorophenylimino)ethyl]pyridine}-1κ3N,N′,N′′;3κ3N,N′,N′′-di-μ-chlorido-1:2κ2Cl:Cl;2:3κ2Cl:Cl-trichlorido-1κCl,2κCl,3κCl-2-copper(I)-1,3-dicopper(II)

The title complex, [Cu3Cl5(C21H17N3F2)2], is the first reported copper trimer including both Cu(I) and Cu(II) ions. The two Cu(II) ions are five-coordinate in a significantly distorted square-pyramidal arrangement, with the bridging Cl atom located in the apical position, and the pyridine (py) N atom, the two imine N atoms and the other Cl atom located in the basal plane. The Cu(I) ion is in a trigonal planar configuration surrounded by three Cl atoms. The structure is stabilized by intra- and intermolecular C-H...Cl and C-H...pi(py) hydrogen bonds.

Dichloro[(1E,1'E)-1,1'-(pyridine-2,6-diyl)diethanone bis(O-methyloxime)-kappa(3)N(1),N(2),N(6)]copper(II).

In the title compound, [CuCl(2)(C(11)H(15)N(3)O(2))], the Cu(II) ion is five-coordinated in a strongly distorted trigonal-bipyramidal arrangement, with the two methyloxime N atoms located in the apical positions, and the pyridine N and the Cl atoms located in the basal plane. The two axial Cu-N distances are almost equal (mean 2.098 A) and are substantially longer than the equatorial Cu-N bond [1.9757 (15) A]. It is observed that the N(oxime)-M-N(pyridine) bond angle for five-membered chelate rings of 2,6-diacetylpyridine dioxime complexes is inversely related to the magnitude of the M-N(pyridine) bond. The structure is stabilized by intra- and intermolecular C-H...Cl hydrogen bonds which involve the methyl H atoms, except for one of the two acetylmethyl groups.