An unprecedented twofold interpenetrating (3,4)-connected 3-D metal-organic framework

An unprecedented twofold interpenetrating (3,4)-connected topology of the Cu(3)L(4)-type metal-organic framework was prepared using N,N',N'-tris(4-pyridinyl)-1,3,5-benzenetricarboxamide (L) as a trigonal three-connection node and the copper(ii) ion as a square planar four-connection node, where the framework contains remarkably large 1-D solvent channels.     

Vinyl‐Type Polymerization of Norbornene Dicarboxylic Acid Dialkyl Esters

Summary: Poly(cis‐norbornene‐exo‐2,3‐dicarboxylic acid dialkyl esters) (alkyl = Me, Et, Pr, Bu, Pen, and Hex) are synthesized as a vinyl‐type with a palladium(II ) catalyst in high yield from easily prepared, pure exo‐monomers. The polymers show good solubility in common organic solvents and excellent thermal stability up to 330 °C. The polymers with alkyl groups larger than methyl exhibit a two‐step thermal degradation profile of an initial thermal degradation of side‐chains starting at 350 °C, followed by thermal degradation of the norbornene backbone starting at ca. 430 °C. The glass transition temperature decreases and the mechanical flexibility increases as the alkyl length of the side‐chain increases.

Normalized loss shear modulus (G″) versus temperature for polynorbornene dicarboxylic acid dialkyl esters.     

Effects of growth temperature on the properties of ZnO/GaAs prepared by metalorganic chemical vapor deposition

A series of ZnO films were grown on GaAs(0 0 1) substrates at different growth temperatures in the range 250–720°C by metalorganic chemical vapor depostion. Field emission scanning electron microscopy was utilized to investigate the surface morphology of ZnO films. The crystallinity of ZnO films was investigated by the double-crystal X-ray diffractometry. The optical and electrical properties of ZnO films were also investigated using room-temperature photoluminescence and Hall measurements. Arrhenius plots of the growth rate versus reciprocal temperature revealed the kinetically limited growth behavior depending on the growth temperature. It was found that the surface morphology, structural, optical and electrical properties of the films were improved with increasing growth temperature to 650°C. All the properties of the film grown at 720°C were degraded due to the decomposition of ZnO film.     

Relationship between oversulfation and conformation of low and high molecular weight fucoidans and evaluation of their in vitro anticancer activity

Low and high molecular weight fucoidans (F(5-30K) and F(>30K)) were chemically modified through the addition of sulfate groups, and the effect of oversulfation on the in vitro anticancer activity was investigated. After the addition of sulfate groups, a considerable increase of 35.5 to 56.8% was observed in the sulfate content of the F(5-30K) fraction, while the sulfate content of the F(>30K) fraction increased to a lesser extent (from 31.7 to 41.2%). Significant differences in anticancer activity were observed between the oversulfated F(5-30K) and F(>30K) fractions, with activities of 37.3-68.0% and 20.6-35.8%, respectively. This variation in the anticancer activity of oversulfated fucoidan derivatives was likely due to differences in their sulfate content. The results suggest that the molecular conformation of these molecules is closely related to the extent of sulfation in the fucan backbones and that the sulfates are preferably substituted when the fucoidan polymers are in a loose molecular conformation.     

Rapid determination of 95 pesticides in soybean oil using liquid-liquid extraction followed by centrifugation, freezing and dispersive solid phase extraction as cleanup steps and gas chromatography with mass spectrometric detection

A multi-residue method using liquid-liquid extraction (LLE) followed by centrifugation, freezing and dispersive solid phase extraction (dispersive SPE) as clean up steps and gas chromatography with mass spectrometric detection has been developed for the determination of trace levels of 95 pesticides in soybean oil. LLE has been optimized to extract these pesticide residues from soybean oil by studying the effect of different partitions between (i) acetonitrile (MeCN) saturated with petroleum ether and a soybean oil solution dissolved in petroleum ether saturated with MeCN, (ii) partition between MeCN and a soybean oil solution dissolved in petroleum ether saturated with MeCN, (iii) partition between MeCN and a soybean oil solution dissolved in petroleum ether, (iv) partition between MeCN saturated with n-hexane and a soybean oil solution dissolved in n-hexane saturated with MeCN, (v) partition between MeCN and a soybean oil solution, (vi) partition between MeCN and a soybean oil solution dissolved in n-hexane and (vii) partition between MeCN and a soybean oil solution dissolved in mixture of acetone and n-hexane (3:2) to the highest recovery yield of pesticides and the lowest co-extract fat residue in the final extract. Experiments were carried out in order to study the efficiency of using centrifugation and freezing steps as well as the used of primary secondary amine (PSA), florisil, graphite carbon black (GCB) and C18 for dispersive SPE on clean up stages to minimize the co-extract fat. The recoveries obtained ranged from 80 to 114% and the relative standard deviation (RSDs) from 2 to 14% for spiking levels of 0.040, 0.080 and 0.160 mg kg^− 1. The limits of quantification (LOQs) of almost all compounds were below the maximum residue limits (MRLs) established by the Korean legislations for soybean oil.     

Determination of the hyperpolarizability components of hemicyanine dyes by measuring the anisotropic fluorescence and second harmonic of the dyes uniformly aligned within zeolite channels

A unidirectional ensemble of hemicyanine molecules was prepared by inserting the molecules into the vertical channels of a uniformly oriented zeolite (silicalite-1) film grown on a glass substrate. Fluorescence from this sample excited with light polarized along the vertical channel was 50 times larger than that excited with light polarized orthogonal to the vertical channel direction. These vertically aligned hemicyanine dyes were used to determine the ratio of the molecular hyperpolarizability components beta(zxx)/beta(zzz) of hemicyanine.     

Assembly of a heterobinuclear 2-D network: a rare example of endo- and exocyclic coordination of Pd(II)/Ag(I) in a single macrocycle

The S3O2 macrocycle L1 was synthesized by a dithiol-dihalide coupling reaction under high-dilution conditions. The reaction of L1 with K2PdCl4 afforded an exocoordinated complex 1, [cis-Cl2Pd(L1)], which can then be manipulated to provide a heterobinuclear complex 3, {[Pd(L1)Ag(NO3)(2.5)](NO3)(0.5)}n, utilizing endocyclic Pd(II) and exocyclic Ag(I) in a single macrocycle through a successive reaction with AgNO3. The network of 3 contains a unique honeycomb-like 2-D sheet made up of the repeating unit [Ag6(NO3)6].