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991.
992.
The microwave-mediated self-assembly of [W(V)(CN)(8)](3-) with Cu(II) in the presence of pyrazole ligand resulted in the formation of three novel assemblies: Cu(II)(2)(Hpyr)(5)(H(2)O)[W(V)(CN)(8)](NO(3))·H(2)O (1), {Cu(II)(5)(Hpyr)(18)[W(V)(CN)(8)](4)}·[Cu(II)(Hpyr)(4)(H(2)O)(2)]·9H(2)O (2), and Cu(II)(4)(Hpyr)(10)(H(2)O)[W(V)(CN)(8)](2)(HCOO)(2)·4.5H(2)O (3) (Hpyr =1H-pyrazole). Single-crystal X-ray structure of 1 consists of cyanido-bridged 1-D chains of vertex-sharing squares topology. The structure of 2 reveals 2-D hybrid inorganic layer topology with large coordination spaces occupied by {Cu(Hpyr)(2)(H(2)O)(4)}(2+) ions. Compound 3 contains two types of cyanido-bridged 1-D chains of vertex-sharing squares linked together by formate ions in two directions forming hybrid inorganic-organic 3-D framework (I(1)O(2)). The magnetic measurements for 1-3 reveal a weak ferromagnetic coupling through Cu(II)-NC-W(V) bridges.  相似文献   
993.
The 16-(3-trifluoromethyl)phenoxy PGF analogue travoprost (8a) has potent topical ocular activity. A novel convergent synthesis of 13,14-en-15-ol PGF analogues was developed employing Julia–Lythgoe olefination of the structurally advanced prostaglandin phenylsulfone (5Z)-(+)-15 with a new enantiomerically pure aldehyde ω-chain synthon (S)-(?)-16a. Subsequent hydrolysis of protecting groups and final esterification of fluprostenol (7a) yielded travoprost (8a). The main advantages are the preparation of high purity travoprost (8a) and the application of comparatively cheap reagents. The novel convergent strategy allows the synthesis of a whole series of 13,14-en-15-ol PGF analogues from a common and structurally advanced prostaglandin intermediate 15. The preparation and identification of two synthetic impurities, 15-epi isomer (8b) of travoprost and a new prostaglandin related ester (5Z)-(+)-18, are also described.  相似文献   
994.
The self-assembly of [Cu(II)(dien)(H(2)O)(2)](2+) and [W(V)(CN)(8)](3-) in aqueous solution leads to the formation (H(3)O){[Cu(II)(dien)](4)[W(V)(CN)(8)]}[W(V)(CN)(8)](2)·6.5H(2)O (1). The crystal structure of 1 consists of an unprecedented {[Cu(II)(dien)](4)[W(V)(CN)(8)]}(5+)(∞) chain of (2,8) topology, nonbridging [W(CN)(8)](3-) anions, and crystallization water molecules. The analysis of magnetic behavior of 1 was performed by the density functional theory (DFT) method and magnetic susceptibility measurements. The DFT broken symmetry approach gave two J(CuW) coupling constants: J(ax) = +2.9 cm(-1) assigned to long and strongly bent W-CN-Cu linkage, and the J(eq) = +1.5 cm(-1) assigned to short and less bent W-CN-Cu linkage, located at the axial and the equatorial positions of square pyramidal Cu(II) centers, respectively, in the hexanuclear {W(2)Cu(4)} chain subunit. The dominance of weak-to-moderate ferromagnetic coupling within the chain was confirmed by magnetic calculations. Zero-field susceptibility of the full chain segment {WCu(4)}(n) was calculated by a semiclassical analytical approach assuming that only one W(V) out of five ? spins of the chain unit WCu(4) is treated as a classical commuting variable. The calculation of the field dependence of the magnetization was performed separately by replacing the same spin with the Ising variable and applying the standard transfer matrix technique. The intermolecular coupling between the chain segments and off-chain [W(CN)(8)](3-) entities was resolved using the mean-field approximation set to be of antiferromagnetic character. The magnetic coupling parameters are compared with those of other low dimensional {Cu(II)-[M(V)(CN)(8)]} systems.  相似文献   
995.
Internal solution free ion-selective electrodes were prepared applying for the first time gold nanoparticles as a solid contact layer. The presence of a layer of gold nanoparticles stabilized with aliphatic thiols at the back side of the membrane resulted in highly stable potentiometric responses of the sensors, good selectivities and close to Nernstian slopes. Electrochemical studies have confirmed that the applied material is effectively working as capacitive solid contact, yielding high stability sensors.  相似文献   
996.
Hydrogen peroxide was incorporated into silica xerogel matrix over the concentration range from 3.8 to 68.0 wt% via the sol–gel route. The obtained composites were characterized by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The release rates of H2O2 from the composites into the aqueous phase were examined. In most cases, a 90% release was attained after ca. 10 min, and it was only slightly dependent on H2O2 concentration and particle size. The antimicrobial activity of the composite containing 3.59% H2O2 was evaluated against Escherichia coli and Micrococcus luteus. A comparative assay was carried out for aqueous solution of H2O2 of the same concentration. The results demonstrated a potent microbicidal efficacy of the composite. Furthermore, diffusion range of the hydrogen peroxide from the solid composite into an agar medium matched that of the H2O2 in aqueous solution. The stability tests with the xerogels containing 3.8, 26.4, and 68.0% of H2O2 showed that after 63 days respective losses of the H2O2 at 3 °C were 8.8, 9.7, and 6.2%. Both the DSC results and the stability tests have shown that the molecular water present in the pores stabilizes the composite, probably through improving the binding of the H2O2 molecules onto the silica surface.  相似文献   
997.
Using the ARGUS detector at thee + e storage ring DORIS II at DESY, we have measured the inclusive production ofD 0,D + andD *(2010)+ mesons inB decays and in nonresonante + e annihilation around 10.6 GeV. The inclusive branching ratios forB decays toD 0,D + andD *+ mesons are found to be (52.2±8.2±3.5)%, (27.2±6.3±3.5)% and (34.8±6.0±3.5)% respectively. Thus,D 0 andD + production account for about 70% of the charm produced inB decays, neglectingbu contributions to the total width. The production cross sections and momentum spectra for continuume + e annihilation are also presented.Supported by the German Bundesministerium für Forschung und Technologie, under contract number 054DO51P  相似文献   
998.
999.
Nonradiative electronic energy migration between identical fluorophores is studied numerically in uniaxially oriented polymer films. The reorientation effect of dipole moments induced by film stretching leads to extremely different concentration- and time-courses of emission anisotropy compared to those in disordered system. In particular, the effect of a much weaker concentration depolarization of fluorescence is due to the fact that not only primarily excited molecules contribute to emission anisotropy in oriented films.  相似文献   
1000.
A natural topic of algebraic graph theory is the study of vertex transitive graphs. In the present article, we investigate locally 3‐transitive graphs of girth 4. Taking our former results on locally symmetric graphs of girth 4 as a starting point, we show what properties are retained if we weaken the requirement of local symmetry to local 3‐transitivity.  相似文献   
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