Inter-molecular hydrogen bonding in N-methyl-N'-(pyridin-2-yl)benzene-1,2-di-amine.

The structure of N-methyl-N'-(pyridin-2-yl)benzene-1,2-di-amine, C12H13N3, at 123 K has ortho-rhom-bic (Pna21) symmetry. The title compound displays an unexpected proton-splitting pattern when studied by 1H NMR spectroscopy. The X-ray crystallography analysis determined this to be caused by strong dual N-H⋯N hydrogen bonding.

Chemical modification of wheat-protein-based natural polymers: formation of polymer networks with alkoxysilanes to modify molecular motions and enhance the material performance.

The mechanical performance of plasticized wheat gluten (WG) materials was significantly modified through the formation of different chemical and network structures with alkoxysilanes. The epoxy-functionalized alkoxysilanes were grafted to segments of WG, and then the condensation reactions between alkoxysilane segments occurred during thermal processing to form WG-siloxane networks. The mechanical properties and molecular motions of the networks were dependent on the amount and type of alkoxysilanes applied. A lower amount of alkoxysilanes caused the alkoxysilane molecules to predominately graft onto WG chains without forming linkages between WG segments, which produced an additional plasticizing effect on the WG systems with a longer elongation value and weaker tensile strength at relative humidity (RH) = 50% as compared to the WG system. However, such grafting improved the hydrostability of the materials and generated an improvement in tensile strength at RH = 85%. Increasing the amount of alkoxysilanes in the systems led to the formation of cross-linked WG-siloxane networks via linkages between alkoxysilane segments. Remarkable strength improvement was obtained for the networks with elongation values still higher than the original plasticized WG due to the flexible nature of the siloxane components. A more significant strength improvement was obtained for the WG-SiA systems at both RH = 50% and 85%, where SiA could form three-dimensional networks from siloxane condensation and generate highly cross-linked network structures with relatively low mobility. For WG-SiB systems, SiB could only form linear linkages, and the higher mobility of the SiB phase caused the systems to display a lower strength improvement with a longer elongation value.

1,4-Bis(piperidin-1-ylcarbon-yl)benzene.

The title compound, C(18)H(20)N(2)O(2), has been synthesized by the reaction of terephthaloyl chloride and 1,2,3,6-tetra-hydro-pyridine. This compound crystallizes as discrete mol-ecular species disposed about a crystallographic centre of symmetry, such that half the mol-ecule constitutes the asymmetric unit. The structure shows an envelope conformation for the dehydro-piperidine ring with the amide carbonyl twisted out of the benzene ring plane by 57.3 (2)°.

Koilands from thiophiles: mercury(II) clusters from thiacalixarenes.

Tetra- and hexa-nuclear mercury(II) complexes have been obtained from tetrathiacalix[4]arene and tetramercaptotetrathiacalix[4]arene, respectively, and structurally characterised in the solid state; the complexes provide new digonal and trigonal receptors of the koiland type.