Initial Analysis on the Characteristics and Synthesis of Exopolysaccharides from Sclerotium rolfsii with Different Sugars as Carbon Sources.

Scleroglucan is widely used in the food and chemical industries because of its good rheological property, stability, and emulsification activity. To investigate the influence of different carbon sources on the properties and synthesis of exopolysaccharides (EPS), the three EPSs (GEPS, glucose was used as the carbon source; LEPS, lactose was used as the carbon source; and SEPS, sucrose was used as the carbon source) were determined, respectively. It was found that the yield and viscosity of exopolysaccharides were different. When sucrose and glucose were used as the carbon sources, the viscosity and yield of EPS were both higher than lactose. The scanning electron microscopy (SEM) images showed that the three EPSs had different morphologies, but the monosaccharide analysis showed that they were all composed of glucose units. Fourier transform infrared spectroscopy (FT-IR) proved that there were no additional substituents for the three EPSs. Furthermore, the high performance liquid chromatography (HPLC) results showed that SEPS and LEPS had two fractions. Through the analysis of proteomics data, there were few differences in the metabolic pathways between GEPS and SEPS, but a significant difference between LEPS and SEPS. Our study provides a theoretical basis and reference for understanding the biosynthesis of exopolysaccharides and the development of different types of EPS products.

Mechanistic insights into the role of PC- and PCP-type palladium catalysts in asymmetric hydrophosphination of activated alkenes incorporating potential coordinating heteroatoms.

The impact of the structural attributes of chiral PC- and PCP-palladium catalysts was investigated in the asymmetric hydrophosphination of various heterocycle-functionalized enone substrates. Due to the architecture of the catalysts, they are confronted with potential catalyst deactivation arising from the coordination of the electron-rich heteroatoms (P, O, N and S) to the metal center. A systematic variation of the location and identity of the heteroatoms demonstrated the impact of structural modifications on the substrates, which have a significant influence on both yields (16-99%) and enantioselectivities (0-99%). A detailed discussion on the distinct catalytic mechanisms (intra- vs. inter-molecular addition) provides important information to explain the results obtained.

Computational and carbon-13 NMR studies of Pt-C bonds in P-C-P pincer complexes.

A (13)C{(1)H} NMR based investigation was conducted to examine the electronic properties of C(aryl)-M bonds and their trans influence in P-C(aryl)-P pincer complexes. A series of structurally related platinum pincer complexes were rationally designed and their corresponding (13)C-(195)Pt coupling constants were systematically examined. By methodical substitution of the ligand trans to the organometallic C(aryl)-Pt bond, this study revealed the significant influence of the ligands on the nature of the C(aryl)-M bonds. The single crystal X-ray analysis of the complexes and computational studies further confirmed the observations that the C-M bond exhibits significant π-character.

Palladacycle promoted base controlled regio- and enantioselective hydrophosphination of 2-pyridylacrylate/amide and the cytotoxicity of their gold complexes.

The regioselective asymmetric hydrophosphination of pyridine-functionalized alkenes can be achieved in the presence of stoichiometric amounts of the chiral palladium complex (R)-1. The presence or absence of base affords the respective ß- and α-adducts with excellent regiocontrol. Chiral gold-phosphine complexes incorporating the adducts exhibited good in vitro anticancer activity against the breast cancer cell line MDA-MB-231. Selectivity between the cancer cell line and normal cells was also observed.

A zero-liquid-discharge scheme for vanadium extraction process by electrodialysis-based technology.

The sharp increase of demand for vanadium makes the treatment of the wastewater generated from its extraction process become an urgent problem. In this study, a hybrid process coupling the electrodialysis with the cooling crystallization is put forward for upgrading the conventional vanadium extraction process to zero discharge. Accordingly, the objective of this work lies in evaluating the feasibility of the proposed scheme on the basis of a systematic study on the influences of membrane types and operating parameters on the electrodialysis performance. The results indicate that the relative importance of osmosis and electro-osmosis to overall water transport is closely related to the applied current density. The increase in the applied current density and the decrease in the mole ratio of water and salt flux will contribute to the concentration degree. Moreover, it is worth noting that a relatively large concentration ratio can result in the remarkable decrease of current efficiency and increase of energy consumption. In general, the reclamation scheme can easily achieve the recovered water with relatively low salt content and the highly concentrated Na2SO4 solution (e.g., 300 g/L) for producing high-purity sodium sulphate crystals.

Highly selective anti-cancer properties of ester functionalized enantiopure dinuclear gold(I)-diphosphine.

Two chiral (-)-diphosphine-digold(I) complexes containing mono- and di-methylester substituted diphosphine ligands have been prepared and structurally characterized. Both complexes are highly potent against breast cancer cell line MDA-MB-231 but showed much lower cytotoxicity against the normal human breast epithelial cells MCF10A. When compared with its mono-substituted analogue, the di-methylester substituted complex caused markedly lower and relatively insignificant damage to the normal breast cells. The analogous mono- and di-ethylester substituted complexes with the same stereochemistry exhibited similar anti-cancer properties but with noticeably higher cytotoxicity against the MCF10A cells. The enantiomeric complex (+)-diphosphine-digold(I) complexes containing the di-methylester substituted diphosphine ligand exhibited clearly different biological properties from its (-)-enantiomer. Furthermore, a structurally similar diphosphine-digold(I) complex but in the absence of an ester substituent, killed both the cancerous and the healthy cells indiscriminately. The current study thus revealed that the introduction of multi-esters, particularly methylesters, is an efficient approach to suppress the side-effects and to improve the efficiency of potential gold-based anti-cancer reagents. When combined with the biological observations, the chirality of gold complexes may serve as a sensitive probe for the future mechanistic studies.

Palladacycle catalyzed asymmetric P-H addition of diarylphosphines to N-enoyl phthalimides.

The first asymmetric phospha-Michael addition of diarylphosphines to N-enoyl phthalimides has been developed in the presence of a chiral palladacycle catalyst. A library of free chiral tertiary phosphine adducts were directly obtained with excellent yields and enantioselectivities. Products can be subsequently functionalized to afford ß-phosphinoamides, the direct preparation of which from cinnamides has been notoriously challenging.