Ab-initio crystal structure of hydroxy adipate of nickel and hydroxy subarate of nickel and cobalt from synchrotron powder diffraction and magnetic properties

Organic-inorganic hybrid compounds Ni(II)₅(OH)₆(C₆H₈O₄)₂(1), Ni(II)₅(OH)₆(C₈H₁₂O₄)₂(2) and Co(II)₅(OH)₆(C₈H₁₂O₄)₂(3) have a similar layered structure as determined ab initio from synchrotron powder diffraction analysis. The metal sites are octahedrally coordinated by O atoms. The slabs are built from edge-sharing octahedra in such a way that channels with an average size of 4 Å are formed. Bis-bidentate and bridging dicarboxylate anions lead to a 3D framework. The compounds (1) and (2) order antiferromagnetically below T_N=26.5 and 19.3 K, respectively, while (3) is ferrimagnetic with T_C=16.2 K. Crystal data for compounds are as follows: (1)a=11.6504(1) Å, b=6.8021(3) Å, c=6.3603(1) Å, α=73.52(1)°, β=99.69(1)°, γ=96.16(1)°, R_B=0.070, 668 reflections; (2)a=13.9325(1) Å, b=6.7893(1) Å, c=6.3534(4) Å, α=73.63(1)°, β=95.14(1)°, γ=91.80(1)°, R_B=0.052, 804 reflections; (3)a=13.9806(1) Å, b=6.9588(1) Å, c=6.3967(1) Å, α=73.05(1)°, β=94.51(1)°, γ=92.19(1)°, R_B=0.048, 410 reflections. The space group is P−1 for the three compounds.     

Halogen Dance on 2-Iodobenzofuran and 2-Iodobenzothiophene and Related Reactions

When 2-iodobenzofuran was treated sequentially with lithium 2,2,6,6-tetramethylpiperidide in tetrahydrofuran at −50 °C and an aldehyde, the 2-substituted 3-iodobenzofuran resulting from the halogen dance was the only isolated product. However, from 2-iodobenzothiophene, these conditions led to mixtures in which the 2-substituted 3-iodobenzothiophene was always accompanied by the 2-substituted benzothiophene. The use of 2-bromobenzothiophene as a catalyst made it possible to significantly reduce this competitive dehalogenation. To confirm the halogen dance reaction, the products were unambiguously synthesized by using direct halogenations and deprotolithiation-trapping sequences as key steps. Our efforts to access 2,7-disubstituted and 7-substituted derivatives of benzofuran and benzothiophene have also been reported.     

Self-assembled monolayers: solidification of carbamazepine in Form II at an interface

A self-assembled monolayer incorporating well-spaced biphenyl moieties initiates solidification of carbamazepine at its interface. A detailed analysis of the resulting crystals using X-ray powder diffraction, FTIR-ATR as well as thermomicroscopy, indicates a preference for its crystallization in trigonal (Form II) polymorph.     

Multi-residue analysis of traces of pesticides and antibiotics in honey by HPLC-MS-MS

The aim of this work was to develop an analytical method for simultaneous assay of residues of two families of antibiotics, and three pesticides, in honey. The assays involved a mixture of five tetracyclines, four sulfamides, and the pesticides coumaphos, carbendazim, and amitraz (two metabolites). All the compounds were extracted from honey and pre-concentrated by optimised solid-phase extraction (SPE). Analysis was by high-performance liquid chromatography-mass spectrometry-mass spectrometry (HPLC-MS-MS) using a triple-quadrupole spectrometer in multiple reaction monitoring (MRM) mode in order to identify and quantify the compounds present (Sheth et al J Agric Food Chem 38:1125–1130, 1990). During development of the analytical method a strong matrix effect was found that depended on the floral origin of the honey. This led to the development of a standard additions method to quantify the contaminants sought.     

Vinyl-triphenylamine dyes, a new family of switchable fluorescent probes for targeted two-photon cellular imaging: from DNA to protein labeling

On the basis of our previous work on vinyl-triphenylamine derived DNA fluorophores we explored the structure space around this core by coupling it to diverse cationic, anionic and zwitterionic groups in the aim of targeting different classes of biomolecules. In parallel core modifications were performed to optimize the photophysical properties (quantum yield, two-photon absorption). The resulting water soluble π-conjugated molecules are called TP dyes and display an exceptional combination of optical properties: high two-photon absorption cross-section, high photostability, no self-quenching, and switchable fluorescence emission when bound to a biopolymer matrix. The linear and nonlinear optical properties of the TP dyes were studied in vitro in presence of DNA and in presence of a model protein (human serum albumin) using complementary absorption and fluorescence spectroscopy characterization tools. Structure modifications enabled to switch from DNA probes (cationic TP-pyridinium series) to protein probes (anionic TP-rhodanine series) without affecting the optical properties. Finally most TP compounds appear cell-permeant and show an intracellular localization consistent with their in vitro target specificity.     

Deproto-metallation and computed CH acidity of 2-aryl-1,2,3-triazoles

2-Aryl-1,2,3-triazoles were synthesized by cyclization of the corresponding glyoxal arylosazones, generated from commercial arylhydrazines. The deproto-metallation of 2-phenyl-1,2,3-triazole was attempted using different 2,2,6,6-tetramethylpiperidino-based mixed lithium-metal (Zn, Cd, Cu, Co, Fe) combinations, giving results in the case of Zn, Cd, and Cu. The lithium-zinc combination was next selected to apply the deprotonation-iodination sequence to all the 2-aryl-1,2,3-triazoles synthesized. The results were analyzed with the help of the CH acidities of the substrates, determined in THF solution using the DFT B3LYP method.     

Evanescent wave cavity ring-down spectroscopy (EW-CRDS) as a probe of macromolecule adsorption kinetics at functionalized interfaces

Evanescent wave cavity ring-down spectroscopy (EW-CRDS) has been employed to study the interfacial adsorption kinetics of coumarin-tagged macromolecules onto a range of functionalized planar surfaces. Such studies are valuable in designing polymers for complex systems where the degree of interaction between the polymer and surface needs to be tailored. Three tagged synthetic polymers with different functionalities are examined: poly(acrylic acid) (PAA), poly(3-sulfopropyl methacrylate, potassium salt) (PSPMA), and a mannose-modified glycopolymer. Adsorption transients at the silica/water interface are found to be characteristic for each polymer, and kinetics are deduced from the initial rates. The chemistry of the adsorption interfaces has been varied by, first, manipulation of silica surface chemistry via the bulk pH, followed by surfaces modified by poly(L-glutamic acid) (PGA) and cellulose, giving five chemically different surfaces. Complementary atomic force microscopy (AFM) imaging has been used for additional surface characterization of adsorbed layers and functionalized interfaces to allow adsorption rates to be interpreted more fully. Adsorption rates for PSPMA and the glycopolymer are seen to be highly surface sensitive, with significantly higher rates on cellulose-modified surfaces, whereas PAA shows a much smaller rate dependence on the nature of the adsorption surface.     

Permanent Polymer Coating for in vivo MRI Visualization of Tissue Reinforcement Prostheses

The clinical advantage of MRI visualization of prostheses in soft tissue prolapses is very appealing as over 1 000 000 MRI‐transparent synthetic meshes are implanted annually, and postoperative complications such as mesh shrinkage and migration are frequent. Here, the synthesis of a new material composed of a DTPA‐Gd complex grafted onto a backbone of PMA via a covalent bond is described (DTPA‐Gd‐PMA). This new polymer is sprayed onto meshes and gives an MR signal for a long period without any significant release of Gd. In vitro cytocompatibility tests on fibroblasts show limited cytotoxicity. Microscopic investigations indicate that vital cells rapidly colonize the material. Finally, coated meshes implanted in rats are easily recognizable using an MR imaging system.

     

Inhibition of histone deacetylase 3 protects beta cells from cytokine-induced apoptosis

Cytokine-induced beta-cell apoptosis is important to the etiology of type-1 diabetes. Although previous reports have shown that general inhibitors of histone deacetylase (HDAC) activity, such as suberoylanilide hydroxamic acid and trichostatin A, can partially prevent beta-cell death, they do not fully restore beta-cell function. To understand HDAC isoform selectivity in beta cells, we measured the cellular effects of 11 structurally diverse HDAC inhibitors on cytokine-induced apoptosis in the rat INS-1E cell line. All 11 compounds restored ATP levels and reduced nitrite secretion. However, caspase-3 activity was reduced only by MS-275 and CI-994, both of which target HDAC1, 2, and 3. Importantly, both MS-275 and genetic knockdown of Hdac3 alone were sufficient to restore glucose-stimulated insulin secretion in the presence of cytokines. These results suggest that HDAC3-selective inhibitors may be effective in preventing cytokine-induced beta-cell apoptosis.