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991.
D. N. Dybtsev I. E. Sokolov E. V. Peresypkina V. P. Fedin 《Russian Chemical Bulletin》2007,56(2):225-230
Two new scaffold-like metal-organic coordination polymers, [Zn2ndc2bpe]·DMF and [Zn2ndc2dedpbp] ·4DMF (ndc is 2,6-naphthalenedicarboxylate, bpe is trans-bis(4-pyridyl)ethylene, and dedpbp is 4,4′-diethynyl-4″,4′″-dipyridylbiphenyl), were synthesized by heating stoichiometric
amounts of zinc(II) nitrate, H2ndc, and bpe or dedpbp in DMF. The structures of the polymers were established by X-ray diffraction. Coordination of linear
dicarboxylate ligands to zinc cations gives rise to planar square-grid networks, and additional coordination of the bifunctional
nitrogen-containing ligands results in the formation of scaffold-like triply interpenetrating structures with a primitive
cubic topology.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 219–223, February, 2007. 相似文献
992.
993.
杂氮硅三环是一类具有特殊生理活性的新型有机硅化合物,有关其合成及性质在近20年中已有大量报道。特别是当R为氯甲基时,该化合物的生理活性很高,用它制成的药膏已用来治疗脱发及伤口愈合。因此,1-氯甲基杂氮硅三环(Ⅰ)的分子结构引起了人们的关注,先后有人报道了(Ⅰ)及1-氯甲基-3,7-二甲基,1-氯甲基-3,7,10-三甲基 相似文献
994.
M. Gdaniec B. T. Ibragimov S. A. Talipov 《Journal of inclusion phenomena and macrocyclic chemistry》1990,9(3):231-242
The crystal structures of the lattice inclusion complexes of gossypol with benzene and chloroform have been determined by X-ray structure analysis. The crystals of (C30H30O8)2 · C6H6 (GPBNZ) are triclinic, space groupPI,a = 11.241(3),b = 14.986(4),c = 17.380(4) Å, = 98.89(2), = 99.86(2), = 98.91(2)°,V = 2800(2) Å3,Z = 2,D
x = 1.32 g cm–3, (CuK
) = 7.35 cm–1. The structure has been refined to a finalR value of 0.050 for 6146 observed reflections. The crystals of C30H30O8·CHCl3 (GPCLF) are monoclinic, space groupC2/c,a = 28.464(4),b = 8.948(1),c = 26.480(4) Å, = 108.93(2)°,V = 6380(2) Å3,Z = 8,D
x = 1.33 g cm–3, (CuK) = 30.42 cm–1. The structure has been refined to a finalR value of 0.100 for 1980 observed reflections.GPCLF forms an intercalate-type structure and GPBNZ a clathrate-type structure. There are, however, some similarities in the packing mode of the host molecules in these two structures. On a basis of comparison of the crystal packing of GPCLF and GPBNZ one can postulate that in the desorption process of the intercalate-type GPCLF complex an intermediate clathrate structure of the GPBNZ-type should be formed. 相似文献
995.
996.
Wolfgang Schattke 《Progress in Surface Science》1997,54(3-4):211-227
Photoemission in the vacuum ultraviolet photon regime has proved to be an effective tool for the investigation of valence band surface electronic structure. The interpretation cannot be exclusively confined to the valence bands but has to consider cross sections with realistic final states consistently designed within the one-step model. Therefore especially in the surface sensitive photoemission, several effects hide the final goal of deducing the energetic and wavefunction structure together with microscopic potential parameters through a convincing agreement of calculated with measured spectra. The final states band structure is much less well understood than the valence band structure under consideration. The optical potential, which controls the surface sensitivity through the underlying damping mechanisms, widely relies on empirical assumptions. Furthermore, the photon field is not only strongly influenced but in the vicinity of the plasma frequency also deteriorated by the electronic response. In view of high resolution spectroscopy the accuracy of the data interpretation is affected, and in fact, band-mapping methods are no longer valid. Examples of recent calculations to account for these effects are reviewed. 相似文献
997.
On vicinal Si(001) surfaces, dependence of growth morphology on the applied strain direction and formation of vacancy lines from Ag-induced missing dimer vacancies are studied. Both phenomena are intimately related to the anisotropic nature of the strain field which originates from the surface dimerization. Strain relief mechanism, reflecting on the surface morphology, is shown to be different in two orthogonal directions. Normal to the steps, step-pair bunching and waving lead to formation of hillocks and pits. Along the step direction, bending of step pairs forms a cusp which later develops into a deep groove. Toward the atomic scale, the formation of the vacancy lines is driven by the short-range attractive interaction between the vacancies in adjacent dimer rows and the long-range repulsive interaction between them in the same dimer row. A full form and magnitudes of the interactions are derived from the thermally-excited wandering of the vacancy lines formed by a nominal amount of Ag depositing onto the surface. 相似文献
998.
由MoO3和(CH3)3N或(C2H5)3N反应合成了两种分子组成分别为[(CH3)3NH]4Mo8O26·2H2O(1)和[(C2H5)3NH]4Mo8O26·2H2O(2)的化合物.单晶X衍射结构分析表明,化合物(1)属三斜晶系,空间群为P1,晶胞参数a=1.0500(2)nm,b=1.0533(2)nm,c=1.0765(2)nm,α=100.21(3)°,β=101.93(3)°,γ=118.47(3)°,V=0.9698(3)nm3,R1=0.0524.化合物(2)属单斜晶系,空间群为P21,晶胞参数a=1.1512(2)nm,b=1.3097(3)nm,c=1.7610(4)nm,β=101.40(3)°,V=2.6028(9)nm3,R=0.0428.结构分析表明,两种化合物中Mo8O264-阴离子均发生畸变,有机阳离子增大,Mo-O键键长缩短,阴离子畸变增大. 相似文献
999.
Introduction Manganeseionsplayanimportantroleinthelight in ducedoxidationofwatertomolecularoxygeninphotosys temII (PSII)ofgreenplants.1 3Inrecentyears ,man ganesecomplexesofpolypyridineligands ,suchasbipyri dine ,1,10 phenanthrolineand 2 ,2′:6′,2″ terpyridine ,havehadconsiderableattentionasthecomplexesformedareusefulmodelsformanganese containingbimolecu lars .4 6 Therefore ,synthesisandcharacterizationofman ganeseinitsvariousoxidationstates ,withvariousligandtypesandnuclearities ,hav… 相似文献
1000.
K. A. Khaldoyanidi 《Journal of Structural Chemistry》2003,44(1):116-129
The paper considers model phase diagrams of binary and ternary systems involving transformations (transitions) of phase equilibria. The relationship between the type of structural solidstate transformation and the type of phase diagram is shown. Topological series of phase diagrams of systems with continuous and limited types of solid solutions are considered, including phase diagrams with polymorphic transitions between intermediate solid phases of variable composition. 相似文献