Isolation and characterization of a novel multibridged tetradentate dianionic form of pyridoxic acid. Crystal structure of tetranuclear [Cu4(PAA)2(Bipyam)4(H2O)2Cl2](NO3)2·CH3OH·10H2O

The X-ray analysis of the tetranuclear copper(II) complex formed from pyridoxic acid and 2,2′-dipyridylamine reveals a novel metal binding mode of pyridoxic acid as a multibridged tetradentate dianion. Here the pyridoxic acid moiety uses all possible sites except the pyridine nitrogen for metal coordination.

Structure of bovine prothrombin fragment 1 refined at 2.25 Å resolution

The structure of bovine prothrombin fragment 1 has been refined at 2.25 Å resolution using high resolution measurements made with the synchrotron beam at CHESS. The synchrotron data were collected photographically by oscillation methods (R-merge = 0.08). These were combined with lower order diffractometer data for refinement purposes. The structure was refined using restrained least-squares methods with the program PROLSQ to a crystallographic R-value of 0.175. The structure includes 105 water molecules with occupancies of >0·6. The first 35 residues (Ala1-Leu35) of the N-terminal ?-carboxy glutamic acid-domain (Ala1-Cys48) of fragment 1 are disordered as are two carbohydrate chains of Mr ? 5000; the latter two combine to render 40% of the structure disordered. The folding of the kringle of fragment 1 is related to the close intramolecular contact between the inner loop disulfide groups. Half of the conserved sequence of the kringle forms an inner core surrounding these disulfide groups. The remainder of the sequence conservation is associated with the many turns of the main chain. The Pro95 residue of the kringle has a cis conformation and Tyr74 is ordered in fragment 1, although nuclear magnetic resonance studies indicate that the comparable residue of plasminogen kringle 4 has two positions. Surface accessibility calculations indicate that none of the disulfide groups of fragment 1 is accessible to solvent.

Synthesis and electrical properties of the (PVA)(0.7)(Kl)(0.3)center dot xH(2)SO(4) (0 <= x <= 5) polymer electrolytes and their performance in a primary Zn/MnO2 battery

Solid acid polymer electrolytes (SAPE) were synthesised using polyvinyl alcohol, potassium iodide and sulphuric acid in different molar ratios by solution cast technique. The temperature dependent nature of electrical conductivity and the impedance of the polymer electrolytes were determined along with the associated activation energy. The electrical conductivity at room temperature was found to be strongly depended on the amorphous nature of the polymers and H2SO4 concentration. The ac (100 Hz to 10 MHz) and dc conductivities of the polymer electrolytes with different H2SO4 concentrations were analyzed. A maximum dc conductivity of 1.05 x 10(-3) S cm(-1) has been achieved at ambient temperature for electrolytes containing 5 M H2SO4. The frequency and temperature dependent dielectric and electrical modulus properties of the SAPE were studied. The charge transport in the present polymer electrolyte was obtained using Wagner's polarization technique, which demonstrated the charge transport to be mainly due to ions. Using these solid acid polymer electrolytes novel Zn/SAPE/MnO2 solid state batteries were fabricated and their discharge capacity was calculated. An open circuit voltage of 1.758V was obtained for 5 M H2SO4 based Zn/SAPE/MnO2 battery. (C) 2010 Elsevier Ltd. All rights reserved.

Arene ruthenium complexes of N,N′- and N,O-donor schiff base ligands: an X-ray structure of [(η6-p-cymene) RuCl(C5,H4N-2-CH=NC6H4-p-Me)Cl·C6H6·H2O

Arene ruthenium(II) Schiff base complexes of formulations [(η -p-cymene)RuCl(C5H4N-2-CH=NC6H4-p-X)](ClO4) (1) and [(η6-p-cymene)RuCl(O-o-C6H4CH=NC6H4-p-X)] (2) (X = H, Me, OMe, NO2, Cl) were prepared by reacting [(η6-p-cymene)RuCl2]2 with corresponding pyridine-2-carboxaldimines and sodium salts of salicylaldimines in dry THF, respectively. Complex 1 is isolated as a perchlorate salt. The molecular structure of [(η6-p-cymene)RuCl(C5H4 N-2-CH=NC6H4-p-Me)]Cl·C6H6·H2O has been determined by X-ray crystallography. The complex contains an η6-p-cymene group, a chloride and a bidentate chelating Schiff base ligand.

Structural phase transitions in Bi2V1-xGexO5.5-x/2 (x=0.2, 0.4, and 0.6) single crystals: X-ray crystallographic study

Single crystals of Bi2V1-xGexO5.5-x/2 (x = 0.2, 0.4, and 0.6) were grown by slow cooling of melts. Bismuth vanadate transforms from an orthorhombic to a tetragonal structure and subsequently to an orthorhombic system when the Ge4+ concentration was varied from x = 0.2 to x = 0.6. All of these compositions crystallized in polar space groups (Aba2, F4mm, and Fmm2 for x = 0.2, 0.4, and 0.6, respectively). The structures were fully determined by single crystal X-ray diffraction studies, (C) 1999 Elsevier Science Ltd.

A layered chlorophosphate, Na-3[Cd4Cl3(HPO4)(2)(H2PO4)(4)], containing Na+ ions in the interlamellar space

Reaction between CdCl2.H2O and NaH2PO4.H2O Under hydrothermal conditions gives rise to a new cadmium chlorophosphate of the formula Na-3[Cd4Cl3(HPO4)(2)(H2PO4)(4)] I. This material crystallizes in the orthorhombic system with space group Fmm2(no. 42). I has macroanionic layers of [Cd4Cl3(HPO4)(2)(H2PO4)(4)](3-) with Na+ ions in the interlamellar space. The discovery of such compounds suggests that metathetic reactions carried out under hydrothermal conditions may provide a novel route for the synthesis of new open-framework structures.

Halogen Bonding and Structural Modularity in 2,3,4-and 3,4,5-Trichlorophenol

The crystal structure of 3,4,5-trichlorophenol contains hydrogen bonded domains that occur respectively in the structures of 4-chlorophenol and 3,5-dichlorophenol. Such modularity is also seen in 2,3,4-trichlorophenol. These structures, and those of the six isomeric dichlorophenols, illustrate the importance of halogen bonding as a structure determining interaction.

Effect of oxygen pressure on the grain and domain structure of polycrystalline 0.85PbMg(1/3)Nb(2/3)O(3)-0.15PbTiO(3) thin films studied by scanning probe microscopy

0.85PbMg(1/3)Nb(2/3)O(3)-0.15PbTiO(3) ferroelectric-relaxor thin films have been deposited on La(0.5)nSr(0.5)CoO(3)/(1 1 1) Pt/TiO(2)/SiO(2)/Si by pulsed laser ablation at various oxygen partial pressures in the range 0.05 to 0.4 Torr. All the films have a rhombohedral perovskite structure. The grain morphology and orientation are drastically affected by the oxygen pressure, studied by x-ray diffraction and scanning electron microscopy. The domain structure investigations by dynamic contact electrostatic force microscopy have revealed that the distribution of polar nanoregions and their dynamics is influenced by the grain morphology, orientation and more importantly, oxygen vacancies. The correlation length extracted from autocorrelation function images has shown that the polarization disorder decreases with oxygen pressure up to 0.3 Torr. The presence of polarized domains and their electric field induced switching is discussed in terms of internal bias field and domain wall pinning. Film deposited at 0.4 Torr presents a curious case with unique triangular grain morphology and large polarization disorder.

2-{[{2-Hydroxy-3-[2-methyl-5-(propan-2-yl)phenoxy]propyl}(pyridin -2-ylmethyl)amino]methyl}phenol

In the title racemic compound, C(26)H(32)N(2)O(3), an intramolecular O-H center dot center dot center dot N hydrogen bond is formed between the phenolic OH group and the tertiary amine N atom. Another O-H center dot center dot center dot N hydrogen bond that is formed between the OH group and the pyridine N atom links the molecules into a polymeric chain extending along the a axis. The structure is further stabilized by intramolecular and intermolecular C-H center dot center dot center dot O interactions.

ZnFe(2)O(4): Rapid and sub-100 degrees C synthesis and anneal-tuned magnetic properties

Nanocrystalline zinc ferrite (ZFO) has been synthesized from metal acetylacetonates by microwave irradiation for 5 min in the presence of a surfactant. The as-prepared material is ZFO and has been subjected in air to conventional furnace annealing and to rapid annealing at different temperatures. Both annealing protocols lead to well-crystallized ZFO, with crystallite sizes in the range similar to 8-20 nm, which is ferrimagnetic, even at room temperature, with magnetization attaining saturation. While the magnetization M(S) of conventionally annealed ZFO varies with crystallite size in the expected manner, rapid annealing leads to high M(S) even when the crystallite size is relatively large. The coercivity is greater in the conventionally annealed ZFO. Thermal and magnetic measurements suggest that the inhomogeneous site cationic distribution within each crystallite caused by rapid annealing can be used to tailor the magnetic behaviour of nanocrystalline ferrites.

Synthesis and an Evaluation of Molecular Conformation and Crystal Packing in Two Substituted 4-Phenylquinolines

The title compounds, namely Methyl 2-methyl-4 -phenylquinoline-3-carboxylate (I), C18H15NO2, and (2E)-3-(3,4-dimethoxyphenyl)-1-(2-methyl-4 -phenylquinolin-3-yl)prop-2-en-1-one (II), C27H23NO3, comprising of the phenyl ring, exhibit differences in conformational behaviour with respect to the plane of the quinoline fragment. (I) contains the methyl ester moiety whereas (II) contains the chalcone fragment, consisting of a double bond and phenyl group containing dimethoxy groups as substituents. The dihedral angles between the phenyl group and the quinoline ring is 82.77 (7)A degrees in (I), and 79.02 (8)A degrees in (II) respectively. It is the weak C-H center dot center dot center dot O=C H-bond and C-H center dot center dot center dot pi interactions which dictate packing of molecules in (I). In (II), it is C-H center dot center dot center dot N and C-H center dot center dot center dot pi, involving the dimethoxy ring, which controls packing of molecules in the crystal lattice. In addition, pi center dot center dot center dot pi aromatic stacking interactions involving the quinoline fragment is present in all the molecules. The title compounds, namely methyl-2-methyl-4 -phenylquinoline-3-carboxylate (I), C18H15NO2, and (2E)-3-(3,4-dimethoxyphenyl)-1-(2-methyl-4 -phenylquinolin-3-yl)prop-2-en-1-one (II), C27H23NO3, comprising of the phenyl ring, exhibit differences in conformational behaviour with respect to the plane of the quinoline fragment. (I) contains the methyl ester moiety whereas (III) contains the chalcone fragment, consisting of a double bond and phenyl group containing dimethoxy groups as substituents. The dihedral angles between the phenyl group and the quinoline ring is 82.77 (7)A degrees in (I), and 79.02 (8)A degrees in (II) respectively. It is the weak C-H center dot center dot center dot O=C H-bond and C-H center dot center dot center dot pi interactions which dictate packing of molecules in (I). In (II), it is C-H center dot center dot center dot N and C-H center dot center dot center dot pi, involving the dimethoxy ring, which controls packing of molecules in the crystal lattice. In addition, pi center dot center dot center dot pi aromatic stacking interactions involving the quinoline fragment is present in all the molecules.

Imaging Intracellular Zinc by Using a Glyoxal Bis(4-methyl-4-phenyl-3-thiosemicarbazone) Ligand

The ligand glyoxal bis(4-methyl-4-phenyl-3-thiosemicarbazone) (GTSCH2) is shown to be a selective fluorescence turn-on sensor for zinc ions (Zn2+). This sensor is easy to synthesize, exhibits excellent sensitivity and selectivity towards Zn2+ over other physiologically relevant cations, and has sub-nanomolar binding affinity. It displays maximum fluorescence response to Zn2+ when the metal/ligand ratio is 1:1 and displays stable fluorescence over a broad pH range. The potential of GTSCH2 to image Zn2+ inside the cell was demonstrated in MCF-7 cells (human breast cancer cell line) by using flow cytometry and confocal fluorescence microscopy. Cell viability studies reveal that the probe is biocompatible and suitable for cellular applications.

Stepwise Crystallization: Illustrative Examples of the Use of Metalloligands Cu-6(mna)(6)](6-) and (Ag-6(Hmna)(2)(mna)(4)](4-) (H(2)mna=2-Mercapto Nicotinic Acid) in the Formation of Heterometallic Two- and Three-Dimensional Assemblies with brucite, pcu, and sql Topologies

Three new inorganic coordination polymers, {Mn(H2O)(6)]-Mn-2(H2O)(6)](Cu-6(mna)(6)]center dot 6H(2)O}, 1, {Mn-4(OH)(2)(H2O)(10)] (Cu-6(mna)6]center dot 8H(2)O}, 2, and {Mn-2(H2O)(5)]Ag-6(Hmna)(2)(mna)(4)]center dot 20H(2)O}, 3, have been synthesized at room temperature through a sequential crystallization route. In addition, we have also prepared and characterized the molecular precursor Cu-6(Hmna)(6)]. Compounds 1 and 3 have a two-dimensional structure, whereas 2 has a three-dimensional structure. The formation of 2 has been achieved by minor modification in the synthetic composition, suggesting the subtle relationship between the reactant composition and the structure. The hexanudear copper and silver duster cores have Cu center dot center dot center dot Cu and Ag center dot center dot center dot Ag distances close to the sum of the van der Waals radii of Cu1+ and Ag1+, respectively. The connectivity between Cu-6(mna)(6)](6-) cluster units and Mn2+ ions gives rise to a brucite related layer in 1 and a pcu-net in 2. The Ag-6(Hmna)(2)(mna)(4)](4-) cluster in 3, on the other hand, forms a sql-net with Mn2+. Compound 1 exhibits an interesting and reversible hydrochromic behavior, changing from pale yellow to red, on heating at 70 degrees C or treatment under a vacuum. Electron paramagnetic resonance studies indicate no change in the valence states, suggesting the color change could be due to changes in the coordination environment only. The magnetic studies indicate weak antiferromagnetic behavior. Proton conductivity studies indicate moderate proton migrations in 1 and 3. The present study dearly establishes sequential crystallization as an important pathway for the synthesis of heterometallic coordination polymers.

New low band gap 2-(4-(trifluoromethyl)phenyl)-1H-benzod]imidazole and benzo1,2-c; 4,5-c `]bis1,2,5]thiadiazole based conjugated polymers for organic photovoltaics

Two new low band gap D-A structured conjugated polymers, PBDTTBI and PBDTBBT, based on 2-(4-(trifluoromethyl)phenyl)-1H-benzod]imidazole and benzo1,2-c; 4,5-c']bis1,2,5]thiadiazole acceptor units with benzo1,2-b; 3,4-b']dithiophene as a donor unit have been designed and synthesized via a Stille coupling reaction. The incorporation of the benzo1,2-c; 4,5-c']bis1,2,5]thiadiazole unit into PBDTBBT has significantly altered the optical and electrochemical properties of the polymer. The optical band gap estimated from the onset absorption edge is similar to 1.88 eV and similar to 1.1 eV, respectively for PBDTTBI and PBDTBBT. It is observed that PBDTBBT exhibited a deeper HOMO energy level (similar to 4.06 eV) with strong intramolecular charge transfer interactions. Bulk heterojunction solar cells fabricated with a configuration of ITO/PEDOT: PSS/PBDTBBT: PC71BM/Al exhibited a best power conversion efficiency of 0.67%, with a short circuit current density of 4.9 mA cm(-2), an open-circuit voltage of 0.54 V and a fill factor of 25%.

Ligand 5,10,15,20-Tetra(N-methyl-4-pyridyl)porphine (TMPyP4) Prefers the Parallel Propeller-Type Human Telomeric G-Quadruplex DNA over Its Other Polymorphs

The binding of ligand 5,10,15,20-tetra(N-methyl-4-pyridyl)porphine (TMPyP4) with telomeric and genomic G-quadruplex DNA has been extensively studied. However, a comparative study of interactions of TMPyP4 with different conformations of human telomeric G-quadruplex DNA, namely, parallel propeller-type (PP), antiparallel basket-type (AB), and mixed hybrid-type (MH) G-quadruplex DNA, has not been done. We considered all the possible binding sites in each of the G-quadruplex DNA structures and docked TMPyP4 to each one of them. The resultant most potent sites for binding were analyzed from the mean binding free energy of the complexes. Molecular dynamics simulations were then carried out, and analysis of the binding free energy of the TMPyP4-G-quadruplex complex showed that the binding of TMPyP4 with parallel propeller-type G-quadruplex DNA is preferred over the other two G-quadruplex DNA conformations. The results obtained from the change in solvent excluded surface area (SESA) and solvent accessible surface area (SASA) also support the more pronounced binding of the ligand with the parallel propeller-type G-quadruplex DNA.