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11.
Amrita Chakraborty Ann Candice Fernandez Dr. Anirban Som Biswajit Mondal Dr. Ganapati Natarajan Dr. Ganesan Paramasivam Dr. Tanja Lahtinen Prof. Hannu Häkkinen Dr. Nonappa Prof. Thalappil Pradeep 《Angewandte Chemie (International ed. in English)》2018,57(22):6522-6526
The self‐assembled structures of atomically precise, ligand‐protected noble metal nanoclusters leading to encapsulation of plasmonic gold nanorods (GNRs) is presented. Unlike highly sophisticated DNA nanotechnology, this strategically simple hydrogen bonding‐directed self‐assembly of nanoclusters leads to octahedral nanocrystals encapsulating GNRs. Specifically, the p‐mercaptobenzoic acid (pMBA)‐protected atomically precise silver nanocluster, Na4[Ag44(pMBA)30], and pMBA‐functionalized GNRs were used. High‐resolution transmission and scanning transmission electron tomographic reconstructions suggest that the geometry of the GNR surface is responsible for directing the assembly of silver nanoclusters via H‐bonding, leading to octahedral symmetry. The use of water‐dispersible gold nanoclusters, Au≈250(pMBA)n and Au102(pMBA)44, also formed layered shells encapsulating GNRs. Such cluster assemblies on colloidal particles are a new category of precision hybrids with diverse possibilities. 相似文献
12.
Kirk ML Shultz DA Depperman EC Brannen CL 《Journal of the American Chemical Society》2007,129(7):1937-1943
A Valence Bond Configuration Interaction (VBCI) model is used to relate the intraligand magnetic exchange interaction (J) to the electronic coupling matrix element (HAB) in Tp(Cum,MeZn)(SQNN), a compound that possesses a Donor-Acceptor (D-A) SemiQuinone-NitronylNitroxide (SQNN) biradical ligand. Within this framework, an SQ --> NN charge transfer state mixes with the ground state and stabilizes the spin triplet (S = 1). This charge-transfer transition is observed spectroscopically and probed using resonance Raman spectroscopy. In addition, the temperature-dependent electronic absorption spectrum of the Ni(II) complex, Tp(Cum,MeNi)(SQNN), has been studied. Exchange coupling between the S = 1 Ni(II) ion and S = 1 SQNN provides a mechanism for observing the formally spin-forbidden, ligand-based 3GC --> 1CTC transition. This provides a means of determining U, the mean GC --> CTC energy, and a one-center exchange integral, K(0). The experimental determination of J, U, and K(0) permits facile calculation of HAB, and we show that this methodology can be extended to determine the electronic coupling matrix element in related SQ-Bridge-NN molecules. As magnetic susceptibility measurements are easily acquired in the solid state, H(AB) may be effectively determined for single molecules in a known geometry, provided a crystal structure exists for the biradical complex. Thus, SQ-Bridge-NN molecules possess considerable potential for probing both geometric and electronic structure contributions to the magnitude of the electronic coupling matrix element associated with a given bridge fragment. 相似文献
13.
G. Ghiringhelli A. Piazzalunga X. Wang A. Bendounan H. Berger F. Bottegoni N. Christensen C. Dallera M. Grioni J.-C. Grivel M. Moretti Sala L. Patthey J. Schlappa T. Schmitt V. Strocov L. Braicovich 《The European physical journal. Special topics》2009,169(1):199-205
Resonant inelastic x-ray scattering in the soft x-ray
regime has been profiting much from technical advances that have
lowered considerably the instru- mental linewidth. At the ADRESS beam
line of the Swiss Light Source the SAXES spectrometer can be used to
measure RIXS spectra at the L edges of the 3d transition metals
with unprecedented energy resolution, of the order of 100 meV for
Mn, Ni and Cu. We present here some preliminary spectra on CuO,
malachite, NiO, NiCl2, MnO and LaMnO3. The dd excitations
are very well resolved allowing accurate experimental evaluation of
3d state energy splitting. The low energy scale becomes
accessible opening the way to the study of collective excitations in
strongly correlated electron systems, like magnons and orbitons. 相似文献
14.
Marion Musielak Mark L. Brusseau Manuel Marcoux Candice Morrison Michel Quintard 《Transport in Porous Media》2014,104(1):77-90
Experiments have been performed to investigate the sorption of trichloroethene (TCE) vapor by concrete material or, more specifically, the cement mortar component. Gas-flow experiments were conducted using columns packed with small pieces of cement mortar obtained from the grinding of typical concrete material. Transport and retardation of TCE at high vapor concentrations (500 mg L \(^{-1})\) was compared to that of a non-reactive gas tracer (Sulfur Hexafluoride, SF \(_{6})\) . The results show a large magnitude of retardation (retardation factor \(=\) 23) and sorption (sorption coefficient \(=\) 10.6 cm \(^{3}\) g \(^{-1})\) for TCE, compared to negligible sorption for SF \(_{6}\) . This magnitude of sorption obtained with pollutant vapor is much bigger than the one obtained for aqueous-flow experiments conducted for water-saturated systems. The considerable sorption exhibited for TCE under vapor-flow conditions is attributed to some combination of accumulation at the air-water interface and vapor-phase adsorption, both of which are anticipated to be significant for this system given the large surface area associated with the cement mortar. Transport of both SF \(_{6}\) and TCE was simulated successfully with a two-region physical non-equilibrium model, consistent with the dual-medium structure of the crushed cement mortar. This work emphasizes the importance of taking into account sorption phenomena when modeling transport of volatile organic compounds through concrete material, especially in regard to assessing vapor intrusion. 相似文献
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16.
A simple Pd-catalyzed aerobic oxidation of benzylic and aliphatic alcohols to the corresponding aldehydes and ketones at room temperature is described. 相似文献
17.
[reaction: see text] Ruthenium alkylidene complexes 1-3 mediate hydrosilylation of alkynes with silanes. When triethoxy- or triphenylsilanes are used as silylating agents, the reaction affords alpha-substituted vinylsilanes as major products. 相似文献
18.
R.David Crouch Candice A. Romany Anna C. Kreshock Karina A. Menconi Jennifer L. Zile 《Tetrahedron letters》2004,45(6):1279-1281
TES- and TBS-protected alcohols undergo deprotection in good to excellent yield upon heating with 1 equiv of BiOClO4-xH2O in CH2Cl2. TBDPS- and TIPS-protected 2° alcohols are more resistant to deprotection. The use of this method in selective desilylation is, however, limited to the deprotection of alkyl silyl ethers in the presence of TBDPS-protected phenols. 相似文献
19.
The molecular structure of Al(tBu)3(NH2CH2CH2Ph) is determined by the crystal packing of the phenyl rings and the pseudo spherical Al(tBu)3 units, and may be viewed as a layered structure consisting of double sheets of the phenyl rings and the Al(tBu)3 units. The Al–N–C–C linkage shows severe disorder as a result of its flexibility. The structure of Al(tBu)3 (NH2CH2CH2Ph) can be likened to a molecular slinky, in which the rigid ends are fixed in space by molecular packing forces, leaving the interior link to adopt multiple orientations. Crystal data: orthorhombic, Cmca,a=13.282(9),b=25.01(1),c=13.210(9), Å,V=4388(10) Å3,Z=4,R=0.0957,R
w=0.0957. 相似文献
20.