Synthesis and characterization of nano Ag end capped L-cysteine bridged diblock copolymer

The target of the present investigation is synthesis and characterization of an amphiphilic diblock copolymer with antibacterial property. Ring opening polymerization (ROP) of ε-caprolactone (CL) and tetrahydrofuran (THF) was carried out under inert atmosphere by using L-cysteine as a bridging agent in the presence of stannous octoate (SO) as a catalyst. The nano silver end capped diblock copolymer was synthesized by in situ method. Thus obtained nano silver end capped L-cysteine bridged diblock copolymer was characterized by various analytical methods like Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, circular dichroism (CD), fluorescence spectroscopy, gel permeation chromatography (GPC), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM) and zeta potential. The antimicrobial property of the nano silver end capped diblock copolymer against e-coli was tested.     

Size-mediated cytotoxicity of nanocrystalline titanium dioxide, pure and zinc-doped hydroxyapatite nanoparticles in human hepatoma cells

The evolution of the particle size distribution and the surface composition of silicon carbide and titanium carbide nanoparticle (NP) dispersions were studied. The pre-dispersions were prepared using two commonly used protocols for dispersion: stirring and sonication. Two dispersants were investigated (water and Pluronic F108 1?%) at two stages: pre-dispersion and during in vitro assays. Our data show that for each tested condition, different time-dependent results for the surface chemical composition as well as size and percentage of the agglomerates and the primary particles are observed. De-agglomeration and successive or simultaneous cleaning-wrapping cycles of the nanomaterial are observed and are related to the dispersion method and the medium as well as to the chemical stability of the NP surface. Biological response during in vitro assessment was also performed for one given pre-dispersion time condition and demonstrates that the preparation method significantly alters the results.     

Cytocompatible in situ cross-linking of degradable LbL films based on thiol–exchange reaction

Formation of both mechanically durable and programmably degradable layer-by-layer (LbL) films in a biocompatible fashion has potential applications in cell therapy, tissue engineering, and drug-delivery systems, where the films are interfaced with living cells. In this work, we developed a simple but versatile method for generating in situ cross-linked and responsively degradable LbL films, based on the thiol–exchange reaction, under highly cytocompatible conditions (aqueous solution at pH 7.4 and room temperature). The cytocompatibility of the processes was confirmed by coating individual yeast cells with the cross-linked LbL films and breaking the films on demand, while maintaining the cell viability. In addition, the processes were applied to the controlled release of an anticancer drug in the HeLa cells.     

以对二甲苯氧化为对苯二甲酸为例简要综述一级C–H键活化(英文)

The oxidation of para‐xylene to terephthalic acid has been commercialised as the AMOCO process(Co/Mn/Br) that uses a homogeneous catalyst of cobalt and manganese together with a corrosive bromide compound as a promoter. This process is conducted in acidic medium at a high tempera‐ture(175–225 °C). Concerns over environmental and safety issues have driven studies to find mild‐er oxidation reactions of para‐xylene. This review discussed past and current progress in the oxida‐tion of para‐xylene process. The discussion concentrates on the approach of green chemistry in‐cluding(1) using heterogeneous catalysts with promising high selectivity and mild reaction condi‐tion,(2) application of carbon dioxide as a co‐oxidant, and(3) application of alternative promoters. The optimisation of para‐xylene oxidation was also outlined.     

Molecular fibers and wires in solid-state and solution self-assemblies of cyclodextrin [2]rotaxanes

Cyclodextrin [2]rotaxanes have been prepared by coupling dimethylanilines with dicarboxylic acids using DMT-MM, in aqueous solutions of alpha-cyclodextrin, and the example illustrated shows unusual fluorescence emission and other spectroscopic behavior characteristic of the formation of molecular wires in solution, similar to the fibers observed in the solid state.     

Synthesis and Characterization of the Mixed‐Linker Copper(II) Coordination Polymer [Cu(HO3PC6H4SO3)(C10N2H8)]·H2O

A new copper(II) phosphonatobenzenesulfonate incorporating 4,4′‐bipyridine (4,4′‐bipy) as auxiliary ligand has been discovered through systematic high‐throughput (HT) screening of the system Cu(NO₃)₂·3H₂O/H₂O₃PC₆H₄SO₃H/4,4′‐bipy using different solvents. The hydrothermal synthesis of [Cu(HO₃PC₆H₄SO₃)(C₁₀H₈N₂)]·H₂O ( 1 ) was further optimized by screening various copper(II) salts. The crystal structure of 1 was determined by single‐crystal X‐ray diffraction and unveiled the presence of isolated sixfold coordinated Jahn–Teller‐distorted Cu²⁺ ions. The isolated CuN₂O₄ octahedra are interconnected by phosphonate and sulfonate groups to form chains along the c‐axis. The organic groups, namely phenyl rings and 4,4′‐bipy molecules cross‐link the chains into a three‐dimensional framework. Water molecules are found in the narrow voids in the structure which are held by weak hydrogen bonds. Upon dehydration, the structure of 1 undergoes a phase transition, which was confirmed by TG measurements and temperature dependent X‐ray powder diffraction. The new structure of 1‐h was refined with Rietveld methods. Detailed inspection of the structure revealed the directional switching of the Jahn–Teller distortion upon de/rehydration. Weak ferro‐/ferrimagnetic interactions were observed by magnetic investigations of 1 , which switch to antiferromagnetic below 3.5 K. Compounds 1 and 1‐h are further characterized by thermogravimetric and elemental analysis as well as IR spectroscopy.     

A three‐dimensional tin(II) phosphonatobenzenesulfonate with Sn4O12 clusters

The hydrothermal reaction of SnCl₂·2H₂O with 4‐phosphonobenzenesulfonic acid (H₃L) and sodium hydroxide has yielded the title compound, poly[μ‐hydroxido‐μ₇‐(4‐phosphonatobenzenesulfonato)‐ditin(II)], [Sn₂(C₆H₄O₆PS)(OH)]_n. The inorganic building unit is an Sn₄O₁₂ cluster which is composed of edge‐sharing SnO₄ and SnO₅ polyhedra. The clusters are interconnected via P and S atoms from the organic acid to form layers in the ab plane. These layers are linked to each other through pillaring benzene groups parallel to the c axis to form a three‐dimensional structure.     

Investigation of porous Ni-based metal-organic frameworks containing paddle-wheel type inorganic building units via high-throughput methods

In the search of Ni based metal-organic frameworks (MOFs) containing paddle-wheel type building units, three chemical systems Ni(2+)/H(n)L/base/solvent with H(n)L = H(3)BTC (1,3,5-benzenetricarboxylic acid), H(3)BTB (4,4',4',-benzene-1,3,5-triyl-tris(benzoic acid)), and H(2)BDC (terephthalic acid) were investigated using high-throughput (HT) methods. In addition to the conventional heating, for the first time HT microwave assisted synthesis of MOFs was carried out. Six new compounds were discovered, and their fields of formation were established. In the first system, H(3)BTC was employed and a comprehensive HT-screening of compositional and process parameters was conducted. The synthesis condition for the Ni paddle-wheel unit was determined and two compounds [Ni(3)(BTC)(2)(Me(2)NH)(3)]·(DMF)(4)(H(2)O)(4) (1a) and [Ni(6)(BTC)(2)(DMF)(6)(HCOO)(6)] (1b) were discovered (Me(2)NH = dimethylamine, DMF = dimethylformamide). In the second system, the use of the extended tritopic linker H(3)BTB and the synthesis conditions for the paddle-wheel units led to the porous MOF, [Ni(3)(BTB)(2)(2-MeIm)(1.5)(H(2)O)(1.5)]·(DMF)(9)(H(2)O)(6.5) (2), (2-MeIm = 2-methylimidazole). This compound shows a selective adsorption of H(2)O and H(2) with a strong hysteresis. In the third system, H(2)BDC was used, and the base (DABCO) was incorporated as a bridging ligand into all structures. Thus, two pillared layered porous MOFs [Ni(2)(BDC)(2)(DABCO)]·(DMF)(4)(H(2)O)(1.5) (3a) and [Ni(2)(BDC)(2)(DABCO)]·(DMF)(4)(H(2)O)(4) (3b) as well as a layered compound [Ni(BDC)(DABCO)]·(DMF)(1.5)(H(2)O)(2) (3c) were isolated. The 3a and 3b polymorphs of the [Ni(2)(BDC)(2)(DABCO)] framework can be selectively synthesized. The combination of microwave assisted heating, low overall concentration, stirring of the reaction mixtures, and an excess of DABCO yields a highly crystalline pure phase of 3b. The fields of formation of all compounds were established, and scale-up was successfully performed for 1b, 2, 3a, 3b, and 3c. All compounds were structurally characterized. In addition to IR, elemental and TG analyses, gas and vapor sorption experiments were carried out.     

Pyrolysis of residual palm oil in spent bleaching clay by modified tubular furnace and analysis of the products by GC–MS

In this study, spent bleaching clay containing 26.6 wt.% of residual palm oil was pyrolyzed using a tubular furnace. Carboxylic acids ranging from C₉-C₁₈ and alkanes ranging from C₁₆-C₄₄ were the major classes of compounds found in the pyrolytic products analyzed using GC-MS. Significant amounts of monoaromatic compounds, alkenes, alcohols, ketones, aldehydes, esters, nitrogenated compounds, and polycyclic aromatic hydrocarbons (PAHs) were found in the bio-oil produced in this study. The bio-oil resulting from the pyrolysis process gave n-hexadecanoic acid as the major compound. Decomposition temperature of the adsorbed oil determined using TGA was found to be in the range of 573-683 K. Topographical and elemental analyses of the clay was done using SEM-EDX. The functional groups were determined using FTIR.