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951.
Dominique Armspach Dominique Matt Laurent PoortersRafael Gramage-Doria Peter JonesLoïc Toupet 《Polyhedron》2011,30(4):573-578
The X-ray crystal structures of trigonal silver(I) cyclodextrin complexes of introverted bidentate sulfur (1) and phosphorus (2) ligands give a clear indication on how a cyclodextrin-included ligand may bind in a ditopic fashion both the encapsulated metal ion and the cyclodextrin inner wall. In the solid state, the silver-coordinated water molecule of complex [Ag(H2O)(1)]BF4 induces a major distortion of the macrocyclic structure, along with dramatic conformational changes in the two opposite glucose units with which it is hydrogen bonded. In complex [AgBr(2)], the included bulky bromide anion, which lacks hydrogen bonding capability, does not affect the overall circular shape of the cyclodextrin receptor. A 1H-19F HOESY experiment conducted on the silver(I) complex of 1 in CDCl3 showed that in this solvent, the water molecule is displaced by the BF4 counterion at the metal coordination site, the cavity being here no longer distorted. 相似文献
952.
Inès Ouerfelli Rafik Gatri Mohamed Lotfi Efrit Johann Perruchon Loïc Toupet 《Journal of organometallic chemistry》2011,696(3):670-675
A series of systematically varied ’rigid-rod’ octahedral ruthenium-acetylide complexes, bearing conjugated bis(acylamino)triazine (DAT) substituents capable of ADAD-DADA pairing, of general formula trans-[(dppe)2Ru(Cl)(CC-C6H4-DAT(R)2)] (R = Et, i-Pr, t-Bu, n-C5H11) have been synthesized and thoroughly characterized in solution by 1H NMR and in the solid state. trans-[Ru(-CC-C6H4-DAT(R)2)2(dppe)2] (R = n-C5H11) has also been designed to form discrete oligomeric chains in solution. 相似文献
953.
This work is aimed to show that various problems from different fields can be modeled more efficiently using multiplicative
calculus, in place of Newtonian calculus. Since multiplicative calculus is still in its infancy, some effort is put to explain
its basic principles such as exponential arithmetic, multiplicative calculus, and multiplicative differential equations. Examples
from finance, actuarial science, economics, and social sciences are presented with solutions using multiplicative calculus
concepts. Based on the encouraging results obtained it is recommended that further research into this field be vested to exploit
the applicability of multiplicative calculus in different fields as well as the development of multiplicative calculus concepts. 相似文献
954.
A two-state oscillator in a viscous liquid is composed of a micron-scale particle whose intrinsic dynamics is defined by linear potentials that undergo configuration-coupled transitions and is externally driven by a piecewise constant periodic force of varying amplitude and frequency. This elementary example of "active matter" has the minimal elements that allow us to study synchronization in the presence of thermal fluctuations. Experiments reveal the presence of synchronized states (and Arnol'd tongues), which we explain using analytical and numerical calculations. The system maintains synchronization by adjusting the phase between the bead and the clock. We discuss the relevance of this model to synchronization in real-world systems, including the role of thermal noise. 相似文献
955.
Govindasamy Chandrasekar Karine MouginHamidou Haidara Loïc VidalEnrico Gnecco 《Applied Surface Science》2011,257(9):4175-4179
The anisotropic shape transformation of gold nanorods (GNRs) with H2O2 was observed in the presence of “cethyl trimethylammonium bromide” (CTAB). The adequate oxidative dissolution of GNR is provided by the following autocatalytic scheme with H2O2: Au0 → Au+, Au0 + Aun+ → 2Au3+, n = 1 and 3. The shape transformation of the GNRs was investigated by UV-vis spectroscopy and transmission electron microscopy (TEM). As-synthesised GNRs exhibit transverse plasmon band (TPB) at 523 nm and longitudinal plasmon band (LPB) at 731 nm. Upon H2O2 oxidation, the LPB showed a systematic hypsochromic (blue) shift, while TPB stays at ca. 523 nm. In addition, a new emerging peak observed at ca. 390 nm due to Au(III)-CTAB complex formation during the oxidation. TEM analysis of as-synthesised GNRs with H2O2 confirmed the shape transformation to spherical particles with 10 nm size in 2 h, whereas centrifuged nanorod solution showed no changes in the aspect ratio under the same condition. Au3+ ions produced from oxidation, complex with excess free CTAB and approach the nanorods preferentially at the end, leading to spatially directed oxidation. This work provides some information to the crystal stability and the growth mechanism of GNRs, as both growth and shortening reactions occur preferentially at the edge of single-crystalline GNRs, all directed by Br− ions. 相似文献
956.
New pyrimidine nucleoside derivatives with nitric oxide(NO) donor were systematically synthesized.The antivirus activities of these nucleoside analogues against vesicular stomatitis virus(VSV) in Wish cell were evaluated.It was demonstrated that most of compounds had stronger antiviral acitivity than acyclovir,while their toxicities were similar or lower to acyclovir. 相似文献
957.
(3S,4R)-Bengamide E(2) was synthesized starting from D-glucono-δ-lactone(3) and the key deoxygenation step from 13 to 15 was achieved by the application of NaBH3CN and ZnI2.Compared with natural bengamide E(1),the synthetic compound(35,4R)-bengamide E(2) was inactive against the cell growth of HUVEC and cancer cells.These data represent the significance of the stereochemistry at C-3 and C-4 of bengamides for structural recognition and binding with the target(s). 相似文献
958.
Two new phenethanol glycosides,named ligurobustoside P(1),ligurobustoside Q(2) have been isolated from the leaves of Ligustrum robustum,together with the known compound angoroside A(3) which was firstly isolated from this species.The structures of the two new phenethanol glycosides(1-2) were elucidated by a combination of high-resolution electron ionization mass spectrometry(HR-ESI-MS),1H NMR,13C NMR,HMQC,and HMBC spectra for the first time. 相似文献
959.
We report on the electrochemical behaviour and electropolymerization of self‐assembled monolayers (SAMs) of methylene blue (MB) on gold electrodes. The SAMs of MB on gold electrodes were prepared by immersing the substrates into a solution of 1.0 mM MB in absolute ethanol for different times at room temperature. Cyclic voltammetry experiments exhibited that reductive desorption of MB monolayer takes place at three different potentials on polycrystalline gold electrodes, while reductive desorption of MB monolayer consists of only one peak on single crystal Au(111) substrates. Calculated charge densities for different immersion times indicated that optimal immersion time for self‐assembly of MB is 96 h. Electropolymerization of SAMs of MB on gold electrode was achieved by applying 0.95 V for 1 s in 0.1 M borate buffer solution (pH: 9.0). It was observed that poly(MB) monolayers are highly stable in acidic media. ATR‐FTIR and UV‐vis spectra exhibited differences between monomer and polymer monolayers, which are attributed to surface‐confined electropolymerization. STM image of poly(MB) monolayer on Au(111) substrate revealed a surface that is covered by well‐ordered, collateral nanowires with an average size of 3 nm. 相似文献