共查询到20条相似文献,搜索用时 31 毫秒
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Iurii L. Malaestean Manfred Speldrich Arkady Ellern Svetlana G. Baca Paul Kögerler 《Polyhedron》2010,29(8):1990-1997
Four hexanuclear coordination clusters containing cores of edge-sharing coordination octahedra exemplify how mixed-spin derivatives of a homonuclear parent structure, [(N–O)4], can be realized by a ligand ‘shrink-wrapping’ approach, resulting in [(N–O)4]- and [(N-O)4]-type clusters (L = isobutyrate, N–O = methyldiethanolamine, n-butyldiethanolamine, or triethanolamine). The resulting core structures are either virtually isostructural to the parent structure or differ in the placement of the peripheral metal ions, depending on the mix of structure-directing carboxylate and alkoxyamine ligands with large, flexible alkyl chains. Whereas the and {} complexes show dominant antiferromagnetic exchange, ferrimagnetic coupling features are exhibited by two {} clusters. 相似文献
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Jin L. Liu Andrew W. Hakin Gavin R. Hedwig 《The Journal of chemical thermodynamics》2009,41(11):1232-1238
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Density and ultrasonic speed of four amino acids (glycine, l-alanine, l-valine, and l-leucine) in aqueous sodium fluoride solutions {(0.1 to 0.5) M} have been measured at T = (308.15, 313.15, and 318.15) K. Apparent molar volumes (Vφ), partial molar volumes , transfer volumes and hydration number (nH) are evaluated using density data. Adiabatic compressibility (βs), change (Δβs), and relative change in compressibility (Δβs/β0), apparent molar compressibility (Kφ), partial molar compressibility , transfer compressibility , and hydration number (nH) have been calculated using ultrasonic speed data. The linear correlation of and for a homologous series of amino acids have been used utilised to calculate the contribution of charged end groups (, COO?), CH2 group and other alkyl chain of the amino acids. The analysis shows that the ion–ion interactions are much stronger than ion–hydrophobic interactions over the entire concentration range of sodium fluoride. It is observed that sodium fluoride has a strong dehydration effect on amino acids. 相似文献
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Ivan Cibulka Lubomír Hnědkovský Josef Šedlbauer 《The Journal of chemical thermodynamics》2010,42(2):198-207
Density data for dilute aqueous solutions of two amino acids (glycine, l-alanine) obtained using a flow vibrating-tube densimeter are presented together with partial molar volumes at infinite dilution (standard molar volumes, ) calculated from the measured data. The experiments were performed at temperatures from (298 up to 443) K at pressures close to the saturation line of water, at pressures in the range from (15 to 17) MPa, and at 30 MPa. Values of an analogue of isothermal compressibility, , are also evaluated. Maxima on the curves and are observed and discussed. The new data along with literature values of standard molar volumes and heat capacities are used for generating the recommended parameterization of an equation of state for standard molar thermodynamic properties of the aqueous amino acids. 相似文献
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