Synthesis, crystal structures and luminescent properties of two one-dimensional cadmium(II) coordination polymers generated from polydentate Schiff-base ligand.

Two new one-dimensional coordination polymers {[CdL(2)(H(2)O)(2)](NO(3))(2)(H(2)O)(6)}(n) (1) and {[CdLI(2)](H(2)O)(CH(3)OH)}(n) (2) have been synthesized and characterized by IR, elemental analysis, TG technique, XRPD and complete single crystal structure analyses, where L is bis(pyridin-4-ylmethylene)biphenyl-2,2'-dicarbohydrazide. The Cd(II) atom has a distorted octahedral coordination geometry with N(4)O(2) donors from four ligands and two water molecules in 1 and a distorted tetrahedral coordination geometry with NOI(2) donors from two ligands and two I(-) anions in 2, respectively. Polymer 1 shows a 1D framework structure containing bimetallic 42-membered quadrangular ring units. The adjacent 1D chains are interacted forming a 3D supramolecular network structure through multiform hydrogen bond interactions. In comparison with 1, polymer 2 is a new rampart-type chain and each chain is interacted with each other through hydrogen bond interactions to lead a 2D layer. The luminescent properties of the polymers 1 and 2 were investigated in the solid state at room temperature.

Optimization of fatty alcohol biosynthesis pathway for selectively enhanced production of C12/14 and C16/18 fatty alcohols in engineered Escherichia coli.

BACKGROUND: With the increasing stress from oil price and environmental pollution, aroused attention has been paid to the microbial production of chemicals from renewable sources. The C12/14 and C16/18 alcohols are important feedstocks for the production of surfactants and detergents, which are widely used in the most respected consumer detergents, cleaning products and personal care products worldwide. Though bioproduction of fatty alcohols has been carried out in engineered E. coli, several key problems have not been solved in earlier studies, such as the quite low production of C16/18 alcohol, the lack of optimization of the fatty alcohol biosynthesis pathway, and the uncharacterized performance of the engineered strains in scaled-up system. RESULTS: We improved the fatty alcohol production by systematically optimizing the fatty alcohol biosynthesis pathway, mainly targeting three key steps from fatty acyl-acyl carrier proteins (ACPs) to fatty alcohols, which are sequentially catalyzed by thioesterase, acyl-coenzyme A (CoA) synthase and fatty acyl-CoA reductase. By coexpression of thioesterase gene BTE, acyl-CoA synthase gene fadD and fatty acyl-CoA reductase gene acr1, 210.1 mg/L C12/14 alcohol was obtained. A further optimization of expression level of BTE, fadD and acr1 increased the C12/14 alcohol production to 449.2 mg/L, accounting for 75.0% of the total fatty alcohol production (598.6 mg/L). In addition, by coexpression of thioesterase gene 'tesA, acyl-CoA synthase gene fadD and fatty acyl-CoA reductase gene FAR, 101.5 mg/L C16/18 alcohol was obtained, with C16/18 alcohol accounting for 89.2% of the total fatty alcohol production. CONCLUSIONS: To our knowledge, this is the first report on selective production of C12/14 and C16/18 alcohols by microbial fermentation. This work achieved high-specificity production of both C12/14 and C16/18 alcohols. The encouraging 598.6 mg/L of fatty alcohols represents the highest titer reported so far. In addition, the 101.5 mg/L 89.2% C16/18 alcohol suggests an important breakthrough in C16/18 alcohol production. A more detailed optimization of the expression level of fatty alcohol biosynthesis pathway may contribute to a further improvement of fatty alcohol production.

Two copper(II) complexes with 4-benzoylpyridine ligand: synthesis, crystal structure and luminescent properties.

Two new copper(II) complexes Cu(NCS)2(4-Bzpy)2 (1) and Cu(NO3)2(4-Bzpy)4 (2) (4-Bzpy=4-benzoylpyridine) have been synthesized and characterized by IR, UV, elemental analysis and X-ray crystallography. Cu(II) atom has a square planar environment for 1 and an distorted octahedral environment for 2, respectively. In solid state there are C-H⋯π interactions and C-H⋯S hydrogen bonds between adjacent molecules in complex 1. The molecule of complex 2 is further connected by multiform π-π interactions, C-H⋯π interactions and C-H⋯O hydrogen bonds to form a three-dimensional supramolecular structure. The luminescent properties of the complexes 1 and 2 were both investigated in H2O solution and in solid state at room temperature, respectively.

Problems with the microbial production of butanol.

With the incessant fluctuations in oil prices and increasing stress from environmental pollution, renewed attention is being paid to the microbial production of biofuels from renewable sources. As a gasoline substitute, butanol has advantages over traditional fuel ethanol in terms of energy density and hygroscopicity. A variety of cheap substrates have been successfully applied in the production of biobutanol, highlighting the commercial potential of biobutanol development. In this review, in order to better understand the process of acetone-butanol-ethanol production, traditional clostridia fermentation is discussed. Sporulation is probably induced by solvent formation, and the molecular mechanism leading to the initiation of sporulation and solventogenesis is also investigated. Different strategies are employed in the metabolic engineering of clostridia that aim to enhancing solvent production, improve selectivity for butanol production, and increase the tolerance of clostridia to solvents. However, it will be hard to make breakthroughs in the metabolic engineering of clostridia for butanol production without gaining a deeper understanding of the genetic background of clostridia and developing more efficient genetic tools for clostridia. Therefore, increasing attention has been paid to the metabolic engineering of E. coli for butanol production. The importation and expression of a non-clostridial butanol-producing pathway in E. coli is probably the most promising strategy for butanol biosynthesis. Due to the lower butanol titers in the fermentation broth, simultaneous fermentation and product removal techniques have been developed to reduce the cost of butanol recovery. Gas stripping is the best technique for butanol recovery found so far.