The syntheses and crystal structures of a series of zirconium(IV) and hafnium(IV) complexes with Dawson monovacant phosphotungstate [alpha2-P2W17O61](10-) and in situ-generated Keggin monovacant phosphotungstate [alpha-PW11O39](7-), which was obtained by a reaction of [alpha-PW12O40](3-) with Na2CO3, are described. K15H[Zr(alpha2-P2W17O61)2].25H2O (K-1), K16[Hf(alpha2-P2W17O61)2].19H2O (K-2), (Et2NH2)10[Zr(alpha-PW11O39)2].7H2O (Et2NH2-3), and (Et2NH2)10[Hf(alpha-PW11O39)2].2H2O (Et2NH2-4), being afforded by reactions in aqueous solutions of monolacunary Dawson and Keggin polyoxotungstates with ZrCl2O.8H2O and HfCl2O.8H2O followed by exchanging countercations, were obtained as analytically pure, homogeneous colorless crystals. Single-crystal X-ray structure analyses revealed that the Zr(IV) and Hf(IV) ions are in a square antiprismatic coordination environment with eight oxygen atoms, four of them being provided from each of the two monovacant polyanion ligands. Although the total molecular shapes and the 8-coordinate zirconium and hafnium centers of complexes 1-4 are identical, the bonding modes (bond lengths and bond angles) around the zirconium(IV) and hafnium(IV) centers were dependent on the monovacant structures of the polyanion ligands. Additionally, the characterization of complexes 1-4 was accomplished by elemental analysis, TG/DTA, FTIR, and solution (31P and 183W) NMR spectroscopy.
These results demonstrate that hyperhomocysteinemia reduced bone strength via a reduction of enzymatic cross-links and an increase of nonenzymatic cross-links. RLX may ameliorate hyperhomocysteinemia-induced detrimental cross-linking in rabbits with OVX and may improve bone strength via the amelioration of collagen cross-links.
The introduction of optoelectronic functions into viscoelastic polymers can yield highly sophisticated soft materials for biomedical devices and autonomous robotics. However,v iscoelasticity and excellent optoelectronic properties are difficult to achieve because the presence of al arge number of p-conjugated moieties drastically stiffens apolymer. Here,w er eport av ariation of additive-free viscoelastic conjugated polymers (VE-CPs) at room temperature by using an intact p-conjugated backbone and bulky,yet flexible, alkyls ide chains as "internal plasticizers." Some of these polymers exhibit gel-and elastomer-like rheological behaviors without cross-linking or entanglement. Furthermore,b inary blends of these VE-CPs exhibit an ever-seen-before dynamic miscibility with self-restorable and mechanically induced fluorescence color changes.
HighlightCYP71BE5 from grapevine was identified as a sesquiterpene oxidase capable of transforming α-guaiene to (−)-rotundone, responsible for the characteristic spicy aroma in wines.
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