A new dinuclear molybdenum(V)-sulfur complex containing citrate ligand: synthesis and characterization of K2.5Na2NH4[Mo2O2S2(cit)(2)].5H(2)O

The complex, K2.5Na2NH4[Mo2O2S2(cit)(2)]. 5H(2)O (1), was obtained by crystallization from a solution of (NH4)(2)MoS4, potassium citrate (K(3)cit) and hydroxyl sodium in methanol and water under an atmosphere of pure nitrogen at ambient temperature. The crystals are triclinic, space group , a = 7.376 (3)Angstrom, b = 14.620 (2) Angstrom, c = 14.661 (1) Angstrom, alpha = 71.10 (1)degrees, beta = 81.77 (1)degrees, gamma = 78.27(2)degrees, R = 0.0584 for 2545 observed (I > 2 sigma (I)) reflections. Single crystal structure analysis reveals that citrate ligand coordinated to molybdenum atom through two carboxylato oxygens and one deprotonated hydroxyl oxygen together with two bridging sulfur atoms and a terminal oxygen atom completes distorted coordination octahedron around each molybdenum atom. Principal dimensions are: Mo = O-t, 1.707 Angstrom (av); Mo-S-b, 2.341 Angstrom (av); Mo-O-(hydroxyl), 2.021 Angstrom (av); Mo-O(alpha-carboxyl), 2.1290 Angstrom (av) and Mo-O(beta-carboxyl), 2.268(av) Angstrom. IR spectrum is in agreement with the structure.

A ferric molybdenum phosphate with a tunnel: hydrothermal synthesis and structure of (NH3CH2CH2NH3)(2)center dot(NH3CH2CH2NH2)(3)center dot Na center dot[Fe2Mo12O30(PO4)(HPO4)(4)(H2PO4)(3)]center dot 7H(2)O

A new ferric molybdenum phosphate containing a tunnel structure and crystallographically different clusters has been hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction. A probe reaction of the oxidation of acetaldehyde with H2O2 using the tide compound as catalyst was carried out in a liquid-solid system, showing that the title compound had high catalytic activity in the reaction. (C) 1998 Elsevier Science S.A. All rights reserved.

The unique skeleton of siliceous sponges (Porifera; Hexactinellida and Demospongiae) that evolved first from the Urmetazoa during the Proterozoic: a review

Sponges (phylum Porifera) had been considered as an enigmatic phylum, prior to the analysis of their genetic repertoire/tool kit. Already with the isolation of the first adhesion molecule, galectin, it became clear that the sequences of sponge cell surface receptors and of molecules forming the intracellular signal transduction pathways triggered by them, share high similarity with those identified in other metazoan phyla. These studies demonstrated that all metazoan phyla, including Porifera, originate from one common ancestor, the Urmetazoa. The sponges evolved prior to the Ediacaran-Cambrian boundary (542 million years ago [myr]) during two major "snowball earth events", the Sturtian glaciation (710 to 680 myr) and the Varanger-Marinoan ice ages (605 to 585 myr). During this period the ocean was richer in silica due to the silicate weathering. The oldest sponge fossils (Hexactinellida) have been described from Australia, China and Mongolia and are thought to have existed coeval with the diverse Ediacara fauna. Only little younger are the fossils discovered in the Sansha section in Hunan (Early Cambrian; China). It has been proposed that only the sponges possessed the genetic repertoire to cope with the adverse conditions, e.g. temperature-protection molecules or proteins protecting them against ultraviolet radiation. The skeletal elements of the Hexactinellida (model organisms Monorhaphis chuni and Monorhaphis intermedia or Hyalonema sieboldi) and Demospongiae (models Suberites domuncula and Geodia cydonium), the spicules, are formed enzymatically by the anabolic enzyme silicatein and the catabolic enzyme silicase. Both, the spicules of Hexactinellida and of Demospongiae, comprise a central axial canal and an axial filament which harbors the silicatein. After intracellular formation of the first lamella around the channel and the subsequent extracellular apposition of further lamellae the spicules are completed in a net formed of collagen fibers. The data summarized here substantiate that with the finding of silicatein a new aera in the field of bio/inorganic chemistry started. For the first time strategies could be formulated and experimentally proven that allow the formation/synthesis of inorganic structures by organic molecules. These findings are not only of importance for the further understanding of basic pathways in the body plan formation of sponges but also of eminent importance for applied/commercial processes in a sustainable use of biomolecules for novel bio/inorganic materials.

Unprecedented 5,5-connected (4(7)center dot 6(3)) (4(8)center dot 6(2)) structural topology: A lead biphosphonate with double layered structure

A new lead(II) phosphonate, Pb[(PO3)(2)C(OH)CH3]center dot H2O (1) was hydrothermally synthesized and characterized by IR, elemental analysis, UV, TGA, SEM, and single crystal X-ray diffraction analysis. X-ray crystallographic study showed that complex 1 has a two-dimensional double layered hybrid structure containing interconnected 4- and 12-membered rings and shows an unusual (5,5)-connected (4(7) . 6(3)) (4(8) .6(2)) topology. (C) 2008 Elsevier B.V. All rights reserved.

Comparison of quantum chemistry calculation methods of nucleic acid base-quartets

Nine base-quartets were calculated by six semi-empirical methods and ab initio Hartree-Fork method using STO-3G basis set. The results showed that PM3 method can be use to calculate base quartets, the results of PM3 calculations are close to the ab initio

Synthesis and luminescence properties of hybrid organic-inorganic transparent titania thin film activated by in-situ formed lanthanide complexes

Stable transparent titania thin films were fabricated at room temperature by combining thenoyltrifluoroacetone (TTFA)-modified titanium precursors with amphiphilic triblock poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO, P123) copolymers. The obtained transparent titania thin films were systematically investigated by IR spectroscopy, PL emission and excitation spectroscopy and transmission electron microscopy. IR spectroscopy indicates that TTFA coordinates the titanium center during the process of hydrolysis and condensation. Luminescence spectroscopy confirms the in-situ formation of lanthanide complexes in the transparent titania thin film.

New organic-inorganic perovskite materials with different optical properties modulated by different inorganic sheets

New organic-inorganic perovskites with different PbBr perovskite sheets stabilized by 3- or 4-an-tidinopyridine were synthesized and structurally characterized. 4-Amidinopyridine constructs < 001 >-oriented perovskite with inorganic sheets made up of typical corner-sharing octahedra of PbBr2. Analogous chemistry in the presence of 3-amidinopyridine under the same conditions results in an unusual hybrid perovskite with the inorganic sheets showing a novel framework including both corner-sharing and edge-sharing PbBr2, which is different from any previously reported ones.

Synthesis, structure and optical properties of new organic-inorganic haloplumbates complexes (C5H10N3)PbX4 (X = Br, Cl), (C2H2N4)PbBr3

Layered organic-inorganic composite materials (C5H10N3)PbX4 (X = Br 1, Cl 2) containing histaminium dications were grown via a solution-cooling process, and their structure and optical properties were determined. The organic ligand-histaminium introduced into the corner-sharing octahedra of the 'PbX4- layer' contains both primary ammonium and imidazolium different from the traditionally primary amine found in this system. As comparison, another analogous amine of 3-amino-1,2,4-triazol was used as ligand to coordinate with PbBr2 in acid solution. A novel complex (C2H2N4)PbBr3 (3) was obtained with zigzag PbBr2 chains different from the PbX4 layer in compound as 1 and 2. The hybrid (C5H10N3)PbX4 show exciton absorption at 339 nm for X = Cl and 419 nm for X = Br with the corresponding emission at 360 and 436 nm, respectively. The different PbBr2 chain structure of compound 3 does not show photo luminescence.

Enhanced response induced by polyelectrolyte-functionalized ionic liquid in glucose biosensor based on sol-gel organic-inorganic hybrid material

In this work, a polyelectrolyte-functionalized ionic liquid (PFIL) was firstly incorporated into a sol-gel organic-inorganic hybrid material (PFIL/sol-gel). This new composite material was used to immobilize glucose oxidase on a glassy carbon electrode. An enhanced current response towards glucose was obtained, relative to a control case without PFIL. In addition, chronoamperometry showed that electroactive mediators diffused at a rate 10 times higher in the apparent diffusion coefficient in PFIL-containing matrices. These findings suggest a potential application in bioelectroanalytical chemistry.

Barycenter of energy of lanthanide 4f(N)-(1)5d configuration in inorganic crystals

A semiempirical method for the evaluation of the barycenter of energy of 4f(N-1)5d configurations is presented. The environmental factors affecting the barycenter are given to be the bond volume polarization, fractional covalence of the chemical bond between the central ion and the nearest anion, and presented charge of the nearest anion in the chemical bonds. The barycenter energies of 4f(N-1)5d configurations of Eu2+ and Ce3+ are calculated in various crystals, and the results are in good agreement with the experimental values. A relationship is found between the barycenter of energy of the 4f(N-1)5d configuration on Eu2+ method offers the advantage of applicability to a broad class of luminescence materials and initiates a link between macroscopic properties and microscopic structure.

Preparation and the investigation of its electrochemical and photoluminescent characteristics of organic-inorganic hybrid multilayers containing europium-substituted heteropolytung state

Photoluminescent multilayers were fabricated by layer-by-layer deposition between europium-substituted heteropolytungstate K-13 [Eu(SiW11O39)(2)].28H(2)O (denoted ESW) and a cationic polymer of quaternized poly(4-vinylpyridine) partially complexed with osmium bis(2,2'-bipyridine) (denoted as QPVP-Os) on glassy carbon and quartz substrates. The resulting photoluminescent organic-inorganic hybrid multilayers were characterized by electrochemical impedance spectroscopy, UV-Vis absorption spectrometry, cyclic voltammetry and photoluminescence spectra. Electrochemical impedance spectroscopy, UV-Vis absorption spectrometry and cyclic voltammetry results demonstrated that the multilayers were regular growth each layer adsorption. The photoluminescent properties of the films at room temperature were investigated to show the characteristic Eu3+ emission pattern of D-5(0) --> (7) F-j.

Novel < 110 >-oriented organic-inorganic perovskite compound stabilized by N-(3-aminopropyl) imidazole with improved optical properties

In the organic-inorganic perovskites family, the < 100 >-oriented type has been extensively investigated as a result of its unique magnetic, optical, and electrical properties, and only one type of < 110 >-oriented hybrid perovskite stabilized by methylammonium and iodoformamidinium cations or the latter themselves has been known so far. In this paper, another novel < 110 >-oriented organic-inorganic perovskite (C6H13N3)-PbBr4 (compound 1) has been prepared by reacting N-(3-aminopropyl)imidazole (API) with PbBr2 in hydrobromic acid. The crystal structure is determined, which indicates that the perovskite is stabilized by API. The introduction of the optically active organic ligand API into the hybrid perovskite results in a red shift and a great enhancement of photoluminescence in the perovskite with respect to organic ligand API itself. These results have been explained according to calculation based on density-functional theory. Moreover, the excellent film processing ability for the perovskite (C6H13N3)PbBr4 together with the improved optical properties makes it have potential application in optoelectronic devices.