Pyridine-2,5-dicarboxylic acid complexes of nickel(II) with 2,2′-bipyridine and 1,10-phenanthroline coligands; syntheses,crystal structures,spectroscopic and thermal studies

Two pyridine-2,5-dicarboxylic acid (pydcH₂) complexes of nickel(II) with 2,2′-bipyridine and 1,10-phenanthroline were synthesized and characterized by elemental, spectroscopic, thermal analysis, magnetic measurements and single crystal X-ray diffraction techniques. Both [Ni(pydc)(bipy)₂]·7H₂O and [Ni(pydc)(phen)₂]·6.5H₂O crystallize in the monoclinic system and P2₁/c space group. The Ni(II) ions are coordinated by two bidentate bipy or phen ligands and one pydc dianion in a distorted octahedral geometry. The pydc ligand is coordinated through the pyridine nitrogen atom and oxygen atom of carboxyl group as a bidentate ligand. Both carboxylate groups of pydc are deprotonated but only the 2-carboxylate is coordinated to the metal. Thermal decompositions of the complexes have been studied over the range 30–600 °C on heating in a static air atmosphere.     

A new donor–acceptor double‐cable carbazole polymer with perylene bisimide pendant group: Synthesis,electrochemical, and photovoltaic properties

We report here electrochemical synthesis of novel soluble donor–acceptor (D–A) polymer with suitably functionalized perylenetetracarboxylic diimide dye derivative covalently linked to carbazole moiety (Cbz‐PDI). The band gap, E_g was measured using UV–Vis spectroscopy and compared with that obtained by cyclic voltammetry (CV). Efficient intramolecular electron transfer from carbazole‐donor to perynediimide‐acceptor leads to remarkable fluorescence quenching of the perylene core. Furthermore, spectroelectrochemical property and surface morphology of the polymer film were investigated. Characteristic monoanion and dianion radical bands on the UV–Vis absorption spectra attributed to the electrochemical reduction of the neutral polymer were observed. During the reduction process, red color of the film turned into blue and violet, respectively. Finally, the photovoltaic performance of the D–A double‐cable polymer was checked and nearly 0.1% electrical conversion efficiency is obtained under simulated AM 1.5 solar light with 100 mW/cm² radiation power. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6280–6291, 2009     

A novel nonreflecting boundary condition for unsteady flow

A novel nonreflecting boundary condition, which converges to the specified time‐dependent boundary condition within any degree of accuracy, is introduced for the numerical simulation of hyperbolic systems and validated against the solution of two fundamental boundary value problems in fluids. First, transonic nozzle flow with backward acoustic disturbance is considered. Using high‐order aeroacoustic numerical schemes, the proposed nonreflecting boundary condition yields results that are in excellent agreement with those obtained using conventional nonreflecting boundary conditions based on the method of characteristics as well as with the results of the exact solution. The novel nonreflecting boundary condition, implemented into a semi‐analytical solution algorithm of unsteady bubbly cavitating nozzle flows, is also validated against results obtained using a Lagrangian finite volume scheme. Copyright © 2013 John Wiley & Sons, Ltd.     

Basic sequences in some regular Köthe spaces

In this paper (closed, linear) subspaces of nuclear Köthe spaces are investigated. This has been the topic of various papers by E. Dubinsky, D. Vogt, M. Alpseymen etc. We give complete characterizations for subspaces with basis of unstable Köthe spaces of type D₁, in particular unstable L_f (Drafilev) spaces of type d₁, and regular subspaces of L_f spaces of infinite type without any assumptions on the defining exponent sequence. The method used depends on applying a stability theorem on embeddings of L. Schwartz [17] and the Hall-Koenig theorem [10] on selection of distinct representatives as well as some construction methods of E. Dubinsky [9].     

Synthesis, spectral and thermal properties, and crystal structure of catena-poly-μ-ethylenediamine(dipicolinato)zinc(II) trihydrate, {[Zn(dipic)(μ-en)]·3H2O}n

A novel metal–organic coordination polymer framework formulated as {[Zn(dipic)(μ-en)]·3H₂O} _n (1) (catena-poly-μ-ethylenediamine(dipicolinato)zinc(II) trihydrate) has been synthesized and characterized by spectral method (IR), elemental analysis, thermal analysis (TG, DTG, DTA) and single crystal X-ray diffraction techniques. It crystallizes in the triclinic system, space group P−1. The asymmetric unit contains three hydrogen-bonded water molecules and the Zn atom is five-coordinated by three N and two O atoms. In fact, it is a new one-dimensional zinc complex with the peculiarity of having the ethylenediamine ligand very unusually acting as bridge to form polymeric chains. In the crystal structure, intramolecular O–H···O and intermolecular O–H···O and N–H···O hydrogen bonds result in the formation of a supramolecular structure, in which they seem to be effective in the stabilization of the structure.     

Calculating the matrix exponential of a constant matrix on time scales

We propose a method which simplifies the main result obtained in [A. Zafer, The exponential of a constant matrix on time scales, ANZIAM J. 48 (2006) 99–106] to calculate the matrix exponential of a constant matrix on a time scale.     

Modification of glassy carbon electrode by the electrochemical oxidation of 3‐aminophenylcalix[4]pyrrole in nonaqueous media

3‐Aminophenylcalix[4]pyrrole (3APCP) was grafted to a glassy carbon (GC) surface during the electrochemical oxidation process in 0.1 M tetrabutylammoniumtetra‐fluoroborate (TBATFB) containing acetonitrile solution. The presence of a surface film was confirmed electrochemically by comparing voltammograms of dopamine and ferricyanide redox probes at the bare and modified electrodes. Reflection‐absorption infrared spectroscopy (RAIRS), XPS, atomic force microscopy (AFM), ellipsometry and the contact angle measurements were also employed to characterize 3APCP film on GC electrode. RAIRS analysis revealed that calix[4]pyrrole was bonded to the glassy carbon surface via the etheric linkage. The stability of the modified GC electrode was also studied. Copyright © 2011 John Wiley & Sons, Ltd.     

One-dimensional coordination polymers of Co(II) and Cd(II)-squarate with 2-methylimidazole and 4(5)-methylimidazole ligands

Two new mixed-ligand coordination polymers, {[Co(μ_1,3-sq)(H₂O)₂(2-Meim)₂]·2(2-Meim)}_n (1) and [Cd(μ_1,3-sq)(H₂O)₂(4(5)-Meim)₂]_n (2), (sq = squarate, 2-Meim = 2-methylimidazole, 4(5)-Meim = 5-methylimidazole) have been synthesized and structurally characterized by X-ray crystallography. The spectral (IR and UV–Vis) and thermal analyses are also reported. The Co(II) and Cd(II) ions are distorted octahedrally coordinated by four oxygen atoms of two O¹–O³-bridging squarate ligands and two trans-aqua ligands, and by two nitrogen atoms of the trans-imidazole (2-Meim or 4(5)-Meim) ligands. The structures of 1 and 2 consist of one-dimensional chains of μ-1,3-squarato bridged metal(II) complex units. These chains are held together by hydrogen bonding interactions, forming three-dimensional framework.     

An unprecedented coordination mode of the orotate ligand in novel polynuclear cadmium(II)–orotate complexes

Two novel carboxylate-bridged Cd(II)–orotate polynuclear complexes with 2-(2-ethylamino)pyridine (2-etapy), [Cd(μ-HOr)(2-etapy)]_n (1), and N,N-diethylethylenediamine (N,N-eten) ligands, {[Cd(μ-HOr)(H₂O)(N,N-eten)]·H₂O}_n (2) (H₃Or = orotic acid), have been synthesized and characterized by TGA–evolved gas analysis (TGA–EGA), IR spectroscopy and single crystal X-ray diffraction techniques. The orotate ligand acts as a bridging ligand with two different coordination modes, showing an unprecedented tetradentate coordination mode. The HOr ligand simultaneously chelates Cd(II) ions through the carboxylate oxygen, deprotonated pyrimidine nitrogen atoms and carboxyl oxygen atoms as a tetradentate ligand in 1. In complex 2, the HOr ligand bridges two Cd(II) ions through the carboxylate oxygen and deprotonated pyrimidine nitrogen atoms and oxygen atom of a carboxylate group of a neighbouring complex unit. Three-dimensional (3D) supramolecular structures are generated by hydrogen-bonding, and π···π and C–H···π interactions between the closest chains in both complexes.