Synthesis,crystal structure and catalytic activity for H2O2 disproportionation of the manganese(II) coordination polymer {[Mn(O2C(CF2)8CO2)(phen)2]H2O}n (phen = 1,10-phenanthroline)

The title polymeric complex {[Mn(O₂C(CF₂)₈CO₂)(phen)₂]H₂O}_n was synthesized through the reaction of 1,10-phenanthroline, perfluorosebacic acid and MnCO₃ · H₂O. The molecular structure was characterized by X-ray diffraction, elemental analysis, thermal gravimetry, IR and UV–Vis spectroscopy and its catalytic activity has been studied. X-ray structure analysis shows that each Mn(II) ion is octahedrally coordinated by two bidentate phenanthroline ligands and the carboxylate oxygen atoms from two symmetry related perfluorosebacate ligands, which are coordinated in cisoid positions. The structure consists of polymeric chains, with the perfluorosebacato ligand bridging the Mn(II) ions in a monodentate fashion. Crystallographic characterization shows a supramolecular structure involving hydrogen bonds, π–π and π-ring interactions. The catalytic results indicated that the complex has reasonably good activity towards the disproportionation of hydrogen peroxide into water and dioxygen in methanol and it does not exhibit saturation kinetics with the substrate. The initial reaction rates and their temperature and base dependencies were investigated by monitoring the dioxygen evolution. Kinetic studies revealed a first-order dependence on the catalyst concentration. Activation parameters have been calculated at 301 K.     

The binding of Ca2+ and Mg2+ to human serium albumin: A calorimetric study

The binding of calcium and magnesium to human serum albumin has been studied in the pH region 2.5–8.0 by a calorimetric procedure. Both metal ions bind to the carboxylate groups of albumin. 36 and 44 carboxylate groups appear to be involved in the binding of Ca²⁺ and Mg²⁺, respectively. Based on previously reported results that twelve Ca²⁺ ions are the maximum which can bind to albumin, the results given here support previous X-ray crystallographic evidence that three carboxylate groups can be involved in the binding of a Ca²⁺ by a protein. The data also confirm that Ca²⁺ and Mg²⁺ binding is competitive. Binding of the cations to the carboxylate groups appears to involve the breaking of carboxylate-imidazole hydrogen bonds in the protein. Log K, ΔH and ΔS values obtained for the binding of metal ions to albumin in aqueous solution at 25°C are 2.72 ± 0.02, 0.0 ± 0.1 kcal/mole, and 12.4 ± 0.3 cal/mole K for Ca²⁺ and 1.12 ± 0.05, ?0.2 ± 0.1 kcal/mole, and 4.5 ± 0.3 cal/mole K for Mg²⁺, respectively.     

Structural diversification of the coordination mode of divalent metals with 1,3-propanediaminetetraacetate (1,3-pdta): The missing crystal structure of the s-block metal complex [Sr2(1,3-pdta)(H2O)6]·H2O

This paper reports the synthesis and X-ray characteristics of the missing homonuclear s-block metal complex {[Sr₂(1,3-pdta)(H₂O)₆]·H₂O}_n. In the title compound, the hexadentate 1,3-propanediaminetetraacetate (1,3-pdta) ligand joins to two Sr(II) centers via the diamine chain. Moreover, each Sr(II) is bridged through two carboxylate O atoms and a water molecule to two neighboring Sr(II) ions. The coordination sphere around each Sr(II) ion consists of one diamine nitrogen, four carboxylate oxygens and four water molecules. Comparison with the previously reported M(II)-1,3-pdta complexes reveals that increasing of the ion size results in the incorporation of water molecules into its first coordination sphere and consequent increase of the coordination number (C.N.) from six to seven or eight, while keeping the hexadentate coordination mode of the ligand. Further increase of the metal ion size leads to the loss of the chelating properties of the diamine and formation of a bis-tridentate complex. Associated with it is the change in the binding mode of the carboxylate groups. This forms the basis for classification of divalent metal 1,3-pdta complexes into five distinct structural classes. Additionally, in the present study X-ray powder diffraction and IR spectroscopy were used to distinguish the different structural types of M(II)-1,3-pdta complexes, including Ba[Ba(1,3-pdta)]·2H₂O which has been used for their preparation.     

Synthesis,Characterization, and DNA Binding Properties of Dinuclear Copper（Ⅱ） Complex [Cu2（TATP）2（L-Leu）2（CIO4）2]2·2H2O

A dinuclear copper（Ⅱ） complex[Cu2（TATP）2（L-Leu）2（CIO4）2]2·2H2Owas synthesized and characterized, where, TATP=1,4,8,9-tetraazatriphenylene, and L-Leu=L-leucinate. The complex was crystallized in the triclinic space group P1, with two independent molecules in a unit cell. Two Cu（Ⅱ） ions in each complex [Cu2（TATP）2（L-Leu）2（CIO4）2] molecule were found to be in different coordination geometries, i.e., Cu2 or Cu4 of a distorted square-pyramidal geometry coordinated with two nitrogens of TATP, the amino nitrogen and one carboxylate oxygen of L-Leu and one oxygen of perchlorate, and Cul or Cu3 with an octahedral geometry coordinated with the above stated similar coordinated atoms, and another carboxylate oxygen of L-Leu coordinating to Cu2 or Cu4. The complex can interact with CT-DNA by an intercalative mode and cleave pBR322 DNA in the presence of ascorbate.     

不同基底对TiO2和SiO2薄膜的光学性能的影响

采用溶胶-凝胶法分别在K9玻璃、单晶硅和石英玻璃基底上制备了纳米TiO₂和SiO₂薄膜。利用SEM、UV-Vis及反射式椭圆偏振光谱仪对薄膜的微观结构及光学特性进行了表征和分析。结果表明:3种基底中, 单晶硅基底上TiO₂和SiO₂薄膜折射率最大;在非晶态K9玻璃和石英玻璃基底上TiO₂薄膜折射率和透光率差异较大;SiO₂薄膜在非晶态基底上折射率、透光率相近;3种基底上薄膜的折射率和消光系数都有随波长增大而减小的趋势, 同时Cauchy模型能较好的描述单晶硅基底上两种薄膜在400~800 nm波段的光学性能。     

不同基底对TiO2和SiO2薄膜的光学性能的影响

采用溶胶-凝胶法分别在K9玻璃、单晶硅和石英玻璃基底上制备了纳米TiO₂和SiO₂薄膜。利用SEM、UV-Vis及反射式椭圆偏振光谱仪对薄膜的微观结构及光学特性进行了表征和分析。结果表明：3种基底中, 单晶硅基底上TiO₂和SiO₂薄膜折射率最大;在非晶态K9玻璃和石英玻璃基底上TiO₂薄膜折射率和透光率差异较大;SiO₂薄膜在非晶态基底上折射率、透光率相近;3种基底上薄膜的折射率和消光系数都有随波长增大而减小的趋势, 同时Cauchy模型能较好的描述单晶硅基底上两种薄膜在400~800 nm波段的光学性能。     

二聚体有机锡配合物{[n-Bu2Sn(O2CCH2CS2NC4H8)]2O}2的合成，表征及晶体结构(英)

The title compound, {[n-Bu₂Sn(O₂CCH₂CS₂NC₄H₈)]₂O}₂, has been synthesized by the reaction of (tetrahydro-pyrrodithiolocarbamoylthio)acetic acid with the di-n-bubyltin oxide in 1∶1 molar ratio. The complex has been characterized by elemental analysis, IR and NMR. The crystal structure of it has been determined by X-ray single crystal diffraction. And the results showed that the crystal belongs to triclinic system with space group P1 and some crystal parameters: a=1.220 2(9) nm, b=1.315 8(10) nm, c=1.380 4(10) nm, α=111.215(9)°， β=99.357(9)°， γ=96.075(10)°, V=2.006(2) nm³, Z=1, F(000)=908, μ=1.489 mm^-1, D_c=1.474 g·cm^-3, R₁=0.037 5, wR₂=0.0839. The complex has a centrosymmetric dimer structure mode with a four-membered central endo-cyclic Sn₂O₂ unit in which two bridged oxygen atoms both connect with an exo-cyclic tin atom which has a distorted octahedron. Each of the endo-cyclic tin atoms exhibits a distorted trigonal bipyramid coordination geometry with an additional weak coordination carboxylate oxygen. Four carboxylate ligands are divided into two types. And two of them are bidentate and connecting to each of exo-cyclic tin atoms by using both oxygen atoms, whereas the others bridge to each pair of exo-and endo-cyclic tin atoms utilizing one oxygen atom only. CCDC: 220513.     

N,N-Ethylene-bridged flavinium salts derived from l-valinol: synthesis and catalytic activity in H2O2 oxidations

Three chiral N¹,N¹⁰-ethylene-bridged flavinium salts with a stereogenic centre derived from l-valinol are prepared and investigated as oxidation catalysts. These salts efficiently catalyse chemoselective H₂O₂ oxidation of sulfides to sulfoxides and the oxidation of 3-phenylcyclobutanone to the corresponding lactone at room temperature. The flavinium salts react with hydrogen peroxide to form flavin-10a-hydroperoxide, which is the agent responsible for oxidation of the substrate.     

Thermal decomposition of polymeric aminoborane (H2BNH2)x under hydrogen release

Polymeric aminoborane (H₂BNH₂)_x has been isolated during the thermal decomposition of solid borazane H₃BNH₃ at temperatures below 370 K. Polymeric aminoborane is a white noncrystalline solid, stable at room temperature and up to 380 K. In the temperature range of 380–500 K polymeric aminoborane undergoes a thermal decomposition, which was studied by differential scanning calorimetry (DSC), by thermogravimetry (TG) and by volumetric measurements. The solid residue was characterized by IR spectroscopy, by powder X-ray diffraction (XRD) analysis and by solid state ¹¹B NMR spectroscopy.

The thermal decomposition of polymeric aminoborane (H₂BNH₂)_x is an exothermic process accompanied by evolution of nearly 1 mol hydrogen per mole H₂BNH₂ unit corresponding to the volumetric measurements. The detected mass loss of the solid phase indicates the formation of further gaseous products beside hydrogen. The final mass loss increases with rising heating rate, in contrast to the final amount of evolved hydrogen, which still remains constant.     

Carbonyl reduction with CaH2 and R3SiCl catalyzed by ZnCl2

Ketones and aldehydes were effectively reduced to the corresponding alcohols (or their silyl ethers) by the reaction with CaH₂ and R₃SiCl in the presence of a catalytic amount of ZnCl₂. In the absence of the carbonyl substrate, the reagent reduced R₃SiCl to the corresponding hydrosilane under mild reaction conditions.     

Scanning Auger analysis for the clarification of oxidation and interdiffusion processes during laser ablation of YBa2Cu3O7-x on alloy/oxide substrates

Scanning Auger investigations are reported on layer systems consisting of a metallic substrate, an oxide buffer layer and the YBa₂Cu₃O_7–x (YBCO) high temperature superconductor. By bending the samples under UHV conditions the internal interfaces have been made accessible for the Auger analysis. The examination of the interfaces have shown that an oxidation of the substrate alloy had taken place during the deposition of the YBCO in spite of the buffer layer already being present. Additionally, segregated sulphur has been found on the substrate/buffer interface, which can lead to a loss of adhesion of the layer system. By line scan investigations on samples prepared by ball cratering a carbon enriched zone of approximately 50 nm thickness has been detected at the interface of buffer and YBCO.     

Effects of Coverage,Water, and Defects on Catechol/TiO2 Interface

Catechol adsorbed on TiO₂ is one of the simplest models to explore the relevant properties of dye-sensitized solar cells. However, the effects of water and defects on the electronic levels and the excitonic properties of the catechol/TiO₂ interface have been rarely explored. Here, we investigate four catechol/TiO₂ interfaces aiming to study the influence of coverage, water, and defects on the electronic levels and the excitonic properties of the catechol/TiO₂ interface through the first-principles many-body Green's function theory. We find that the adsorption of catechol on the rutile (110) surface increases the energies of both the TiO₂ valence band maximum and conduction band minimum by approximately 0.7 eV. The increasing coverage and the presence of water can reduce the optical absorption of charge-transfer excitons with maximum oscillator strength. Regarding the reduced hydroxylated TiO₂ substrate, the conduction band minimum decreases greatly, resulting in a sub-bandgap of 2.51 eV. The exciton distributions in the four investigated interfaces can spread across several unit cells, especially for the hydroxylated TiO₂ substrate. Although the hydroxylated TiO₂ substrate leads to a lower open-circuit voltage, it may increase the separation between photogenerated electrons and holes and may therefore be beneficial for improving the photovoltaic efficiency by controlling its concentration. Our results may provide guidance for the design of highly efficient solar cells in future.     

The dehydration of boehmite, γ-AlOOH,to γ-Al2O3

Electron microscopic observations of microstructure, together with studies of the evolution of X-ray and electron diffraction patterns, have been used to provide mechanistic information on the dehydration of boehmite to γ-Al₂O₃. Firing boehmite in air at 400°C produces slow development of a fine, lamellar, porous microstructure, oriented parallel to (001)_γ, the dimensions of which are consistent with the loss of one-quarter of the oxygen atoms of the boehmite lattice. The mechanism proposed for the dehydration is controlled by diffusion in a direction determined by the hydrogen bond chains in the boehmite structure and involves countermigration of the Al cations and protons with crystallographic formation of voids in a coherent cubic close-packed matrix. Final reorganization to give the spinel structure of γ-Al₂O₃ is suggested to involve gradual filling of the tetrahedral cation sites.     

一维链状配位聚合物[Pb_2(C_8H_7O_2)_4(H_2O)_2]_n的合成、晶体结构及荧光性质

<正>近年来,铅的配位聚合物以其丰富的结构与在离子交换和光学等领域中的应用前景[1-3]而引起了广泛关注。由于铅的原子半径较大,可以形成较高的配位数[4-6];另外,二价铅的6s轨道上有一对孤对     

Selective oxidation of crotyl alcohol and crotonaldehyde on V2O5/MgO: In situ FTIR study

The adsorption of crotyl alcohol, crotonaldehyde and crotonic acid on MgO, V₂O₅ and V₂O₅/MgO mixed oxide was studied under oxidizing conditions by in situ FTIR spectroscopy. The results were further analyzed in order to investigate the surface intermediates of crotonaldehyde oxidative dehydrogenation to maleic anhydride. A stable surface compound, alkoxide, was found during the crotyl alcohol adsorption for all oxides at room temperature (RT). The reaction between the adsorbed crotonaldehyde and the oxygen atom of the catalyst resulted in the formation of carboxylate at higher temperatures (T>373 K). The formation of two different reaction products (furane and maleic anhydride) was detected from IR spectra following the crotonaldehyde adsorption at various oxygen pressures. It can be deduced that crotonic acid easily dissociates to form the surface carboxylate-crotonate, which is further oxidized to maleate and consequently to maleic anhydride at 573 K.     

有机锡配合物{[(n-C8H17)2Sn(O2CCH2CS2NC4H8O)]2O}2的合成，表征及晶体结构

The title complex {[(n-C₈H₁₇)₂Sn(O₂CCH₂CS₂NC₄H₈O)]₂O}₂ has been synthesized by the reaction of (morpholinylthiocarbamoylthio)acetic acid with the di-n-octyltin oxide in 1∶1 molar ratio. The complex was characterized by elemental analysis, IR and ¹H NMR. The crystal and molecular structure of complex was determined by X-ray single crystal diffraction. The crystal belongs to triclinic system with space group P1 and unit cell dimensions: a=1.201 5(9) nm, b=1.481 8(11) nm, c=1.894 1(14) nm, α=72.485(10)°, β=88.586(10)°, γ=66.893(9)°, and Z=1, μ=1.034 mm^-1, V=2.941(4) nm³, D_c=1.295 g·cm^-3, F(000)=1 196, R₁=0.058 8, wR₂=0.155 8. The complex is a centrosymmetric structure with a four-membered central endo-cyclic Sn₂O₂ unit in which two bridged oxygen atoms both connect with an exo-cyclic tin atom. The endo-cyclic tin atoms and the exo-cyclic tin atom are all five-coordinate and have coordination geometry of distorted trigonal bipyramid with an additional weak coordination carboxylate oxygen. Four carboxylate ligands are divided into two types. And two of them are monodentate and connecting to each of exo-cyclic tin atoms by using one oxygen atom, whereas the others bridge to each pair of exo-and endo-cyclic tin atoms utilizing one oxygen atom. CCDC: 277048.     

[Cu(Hsal)2(py)2]n晶体结构和二维堆积网络

０引言水杨酸具有羧基和羟基，是双功能基配体，羧基和羟基可分别脱去氢，因此有多种形式可参与配位（见Scheme１），其中Hsal－１的形式仅见一例报道犤１犦，其可靠性有待更多的研究来确证。对铜／水杨酸／吡啶三元体系的研究已有多篇文献报道犤２～４犦，亦有几种化合物合成，例如Cu（Hsal）２（py）２和Cu（sal）（py）２等。配合物Cu（sal）（py）２的可靠性值得怀疑，原文中无合成和表征犤３犦。铜／水杨酸／吡啶衍生物三元体系已有多个晶体结构报道犤５，６犦，但迄今无铜／水杨酸／吡啶三元体系晶体结构报道。对于配合物Cu（Hsal…     

Formation of the heteropolynuclear complex ([NH2(C4H9)2][Au{S2CN(C4H9)2}2][CdCl4])n during the chemisorption of gold(III) with cadmium dibutyldithiocarbamate: Structure and thermal properties

The chemisorption properties of cadmium dibutyldithiocarbamate with respect to [AuCl₄]⁻ in 2M HCl solutions are studied. The heterogeneous reaction of gold(III) binding affords the heteropolynuclear compound ([NH{₂(C₄H₉)₂][Au{S₂CN(C₄H₉)₂}₂][CdCl₄]) _n (I). The molecular and crystal structures of compound I are determined from the X-ray diffraction data. Each of three ions is presented in the structure by two conformers. The irreversible decomposition of some dibutyldithiocarbamate groups is observed during the chemisorption of gold(III), which noticeably decreases the efficiency of gold binding with the sorbent studied and its sorption capacity. The study of the thermal properties of compound I shows that gold(III) is reduced to the metal during thermolysis.     

Tuning the sulfur-heterometal interaction in organolead(IV) complexes of [Pt2(μ-S)2(PPh3)4]

Reactions of [Pt₂(μ-S)₂(PPh₃)₄] with Ph₃PbCl, Ph₂PbI₂, Ph₂PbBr₂ and Me₃PbOAc result in the formation of bright yellow to orange solutions containing the cations [Pt₂(μ-S)₂(PPh₃)₄PbR₃]⁺ (R₃ = Ph₃, Ph₂I, Ph₂Br, Me₃) isolated as PF₆⁻ or BPh₄⁻ salts. In the case of the Me₃Pb and Et₃Pb systems, a prolonged reaction time results in formation of the alkylated species [Pt₂(μ-S)(μ-SR)(PPh₃)₄]⁺ (R = Me, Et). X-ray structure determinations on [Pt₂(μ-S)₂(PPh₃)₄PbMe₃]PF₆ and [Pt₂(μ-S)₂(PPh₃)₄PbPh₂I]PF₆ have been carried out, revealing different coordination modes. In the Me₃Pb complex, the (four-coordinate) lead atom binds to a single sulfur atom, while in the Ph₂PbI adduct coordination of both sulfurs results in a five-coordinate lead centre. These differences are related to the electron density on the lead centre, and indicate that the interaction of the heterometal centre with the {Pt₂S₂} metalloligand core can be tuned by variation of the heteroatom substituents. The species [Pt₂(μ-S)₂(PPh₃)₄PbR₃]⁺ display differing fragmentation pathways in their ESI mass spectra, following initial loss of PPh₃ in all cases; for R = Ph, loss of PbPh₂ occurs, yielding [Pt₂(μ-S)₂(PPh₃)₃Ph]⁺, while for R = Me, reductive elimination of ethane gives [Pt₂(μ-S)₂(PPh₃)₃PbMe]⁺, which is followed by loss of CH₄.     

Theoretical models for activation of CO2 towards hydration (CO2 + H2O → H2CO3) by cationic binding sites

Theoretical models are studied which illustrate how the hydration reaction CO₂ + H₂O → H₂CO₃ can be catalysed by one or two cationic binding sites (NH₄⁺). In the latter, the arrangement of the two bindings sites is held during the course of the reaction, simulating a rigid molecular receptor. Two different arrangements of the binding sites are studied, and their relative abilities to lower the activation energy of the hydration reaction are studied.