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101.
102.
Back Cover: Yoctoliter Thermometry for Single‐Molecule Investigations: A Generic Bead‐on‐a‐Tip Temperature‐Control Module (Angew. Chem. Int. Ed. 13/2014) 下载免费PDF全文
103.
Reaction of N,N'-bis(phosphonomethyl)-1,10-diaza-18-crown-6 (H(4)L) with copper(II) acetate in 1:1 ethanol/water mixed solvents afforded a new crystal-engineered supramolecular metal phosphonate, Cu(H(2)L) (complex 1). By reaction of the same ligand with cadmium(II) nitrate in a 2:1 (M/L) ratio in methanol, a cadmium(II) complex with a 3D network structure was isolated, Cd(2.75)(L)(H(2)O)(7) x 1.5NO(3) x 7H(2)O x MeOH (complex 2). The copper(II) complex crystallized in the monoclinic space group P2(1)/c, with a =10.125(4), b = 14.103(6), and c = 14.537(6) A, beta = 91.049(8) degrees, V = 2075.4(16) A(3), and Z = 2. The Cu(II) ions in complex 1 are 6-coordinated by two phosphonate oxygen atoms, two nitrogen, and two oxygen atoms from the crown ether ring. Their coordination geometry can be described as Jahn-Teller-distorted octahedral, with elongated Cu-O(crown) distances (2.634(4) and 2.671(4) A for Cu(1) and Cu(2), respectively). The other two crown oxygen atoms remain uncoordinated. Neighboring two Cu(H(2)L) units are further interlinked via a pair of strong hydrogen bonds between uncoordinated phosphonate oxygen atoms, resulting in a one-dimensional supramolecular array along the a axis. The cadmium(II) complex is tetragonal, P4(2)/n (No. 86) with a = 20.8150(9) and c = 18.5846(12) A, V = 8052.0(7) A(3), and Z = 8. Among four cadmium(II) atoms in an asymmetric unit, one is 8-coordinated by four chelating phosphonate groups, the second one is 8-coordinated by 6 coordination atoms from a crown ring and two oxygen atoms from two phosphonate groups, the third Cd(II) atom is octahedrally coordinated by three aqua ligands and three phosphonate oxygen atoms from three phosphonate groups, and the fourth one is 6-coordinated by four aqua ligands and two oxygen atoms from two phosphonate groups in a distorted octahedral geometry. These cadmium atoms are interconnected by bridging phosphonate tetrahedra in such a way as to form large channels along the c direction, in which the lattice water molecules, methanol solvent, and nitrate anions reside. The effect of extent of deprotonation of phosphonic acids on the type of complex formed is also discussed. 相似文献
104.
Langlet A Latypov NV Wellmar U Bemm U Goede P Bergman J Romero I 《The Journal of organic chemistry》2002,67(22):7833-7838
Nitration of some 2-substituted pyrimidine-4,6-diones in sulfuric acid was studied, which afforded previously unknown 5,5-gem-dinitropyrimidine-4,6-diones in high yields. The gem-dinitro products were easily attacked by nucleophiles with concomitant formation of gem-dinitroacetyl derivatives, which in turn could be further hydrolyzed to salts of dinitromethane and triureas. 相似文献
105.
A microscopic, driven lattice gas model is proposed for the dynamics and spatiotemporal fluctuations of the precursor film observed in spreading experiments. Matter is transported both by holes and particles, and the distribution of each can be described by driven diffusion with a moving boundary. This picture leads to a stochastic partial differential equation for the shape of the boundary. Explicit analytic results are obtained which agree with the simulations of the lattice gas. 相似文献
106.
If the potential of a scalar field phi which currently provides the "dark energy" of the Universe has a minimum at phi = -M(0)(4)<0, then quantum-mechanical fluctuations could nucleate a bubble of phi at a negative value of the potential. This bubble would then expand at the speed of light. Given that no such bubble enveloped us in the past, we find that any minimum in V(phi) must be separated from the current phi value by more than min[1.5M(0),0.21M(Pl)], where M(Pl) is the Planck mass. We also show that vacuum decay renders a cyclic or ekpyrotic universe with M(0)(4) > or approximately 10(-10)M(4)(Pl) untenable. 相似文献
107.
108.
Equations for the solubility of gases and vapours into dry alcohols from methanol to decan‐1‐ol and into water‐saturated alcohols from butan‐1‐ol to decan‐1‐ol have been compared through the use of the Abraham solvation equation. It is shown that there are noticeable differences in solvation into the dry and wet alcohols, and that these differences become larger as the alcohols become smaller and take up more water. The two main factors that lead to the differences in solvation are the solute hydrogen‐bond basicity, B, and solute size, L. Increase in solute hydrogen‐bond basicity favours the wet alcohols and increase in solute size favours the dry alcohols. Solute hydrogen‐bond acidity plays no part, because the hydrogen‐bond basicity of water, wet alcohols and dry alcohols is almost the same. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
109.
110.
Maryam I. Daneshvar Guillermo A. Casay Gabor Patonay Malgorzata Lipowska Lucjan Strekowski Lawrence Evans III Leila Tarazi Abraham George 《Journal of fluorescence》1996,6(2):69-75
The design and application of a fluorescent fiber-optic immunosensor (FFOI) are reported. The FFOI is utilized for the detection of antibody/antigen binding within the near-infrared (NIR) spectral region. The technique is developed through the combined use of fiber-optic, semiconductor laser-excitation, fluorescence detection, NIR dye, and immunochemical techniques. The antibody is immobilized on the FFOI and utilized as a recognition component for trace amounts of specific antigen. The FFOI is constructed to utilize an antibody sandwich technique. The assay involves the immobilization of the capture antibody on the sensing tip of the FFOI followed by the exposure of the immobilized sensing tip to the antigen. The antigen-coated FFOI is then introduced to a second antibody previously labeled with the NIR dye. Typical measurements are performed in about 15 min. A semiconductor laser provides the excitation (780 nm) of the immune complex. The resulting emission is detected by a silicon photodiode detector (820 nm). The intensity of the resulting fluorescence is directly proportional to the concentration of the antigen. The sensitivity of the analysis reaches 10 ng/ml and the response time is 10–15 min. 相似文献