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Salts of the heteropolytungstates [PW11M(H2O)O39]5-, M=Cu, Co, Mn, with the following complex cations were prepared: [Cu(LL)2(H2O)]2+, [Cu(LL)3]2+, LL= 1,10-phenantroline (phen), 2,2'-bipyridine (bipy), [Cu(phen)2Cl]+, [Co(bipy)2(CO3)]+, and [Co(phen)3]2+, Compounds with [SiW11M(H2O)O39]6-, M=Cu, Co, Mn, and the cations [Co(LL)2(H2O)]2+, and [Co(bipy)2(CO3)]+ were also prepared. Synthesis was carried out in aqueous or nitromethane solutions. The compounds were characterised by elemental and thermal analysis and spectroscopic techniques. Spectroscopic properties and the thermal stability of the polyanions in these compounds could thus be compared with those of simpler salts. BET surface areas were determined. Except for salts of [Cu(bipy)3]2+, the compounds decompose on heating at temperature above 200°C, the exact temperature depending on the cation. Some are stable up to 300°C. For salts of the [Cu(LL)2(H2O)]2+ cations, more detailed thermal studies were performed, based on the infra red spectra of the decomposition products obtained at several temperatures.

AbstractThe increased degree of transformation of leather to a material with thermoplastic properties is shown to increase this material's solubility in both dimethylsulfoxide and in a buffer similar to those used to dissolve high molecular weight proteins. This increase in solubility is controlled by the variable values of the processing parameters, temperature, and pressure, and is interpreted to suggest that this transformation of leather must be accompanied by the destruction of its collagen superstructure into fragments with a much smaller molecular weight. This model is further supported by molecular weight distributions as determined by size exclusion chromatography and by electrophoresis. The results of the investigation at the molecular level are corroborated by scanning electron microscopy of pleathersamples.