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101.
102.
The equilibrium quotients for the formation of Co(NH3)5Cl2+ from Co(NH3)5OH23+ and Cl? were 3.74±0.25 M?1 and 6.07±0.54 M?1 at 45.0°C in 10:1 mole ratio water: dimethyl sulfoxide and in 25 w/w % aqueous ethanol, respectively, and those forthe formation of the ion pair Co(NH3)5OH23+ . Cl? were 1.21±0.20 M?1 and 1.58±0.17 M?1, respectively, in the same solvents. The aquation and anation rateconstants were determined at 45.0°C for these two solvents over the range of chloride-ion concentrations 0.0 ≤ [Cl?] ≤ 0.9 M. The aquation rate constant was essentially independent of chloride-ion concentration in each solvent over this range. The inverse of the pseudo-first-order anation rate constant was linearly dependent on the inverse of the chloride-ion concentration in each solvent. The least squares relationships between (1/kan) and (1/[Cl?]) gave intercepts and ratios of intercept to slope which were analyzed interms of Id and D mechanisms. It was concluded that the data were not satisfied by a D mechanism, but that they were consistent with an Id mechanism. 相似文献
103.
Molecular orbital calculations using CNDO/S parameters are employed to determine bond-orders, charge-densities and the shielding of the 15N and 13C nuclei of a series of ureas and thioureas. For the sterically uncrowded molecules a linear relationship is noticed between the 15N chemical shifts and C---N bond-orders. When steric crowding occurs this simple relationship is no longer applicable. 相似文献
104.
D.C. Reynolds K.K. Bajaj G. Peters C. Leak W.M. Theis P.W. Yu H. Morkoc K. Alavi C. Colvard I. Shidlovsky 《Superlattices and Microstructures》1988,4(6)
Sharp-line structure associated with both the light-hole free exciton (LHFE) and heavy-hole free exciton (HHFE) transitions has been observed in multi-quantum-well (MQW) structures of four well sizes in photoluminescence (PL) and reflection spectra. These spectra have been deconvulated using photoluminescence excitation spectroscopy (PLE). The LHFE and HHFE sharp-line structure is associated with interface structure composed of growth islands at the interface between the barriers and the wells. Estimates of the average interface island sizes for the four different MQW structures are made based on theoretical modelling. A correlation is established between particular LHFE fine structure components and specific HHFE fine structure components. A model is developed to account for the LHFE and HHFE fine structure based on a non-random distribution of the interface structure. The physical location of the excitons is demonstrated to be in regions of the wells with essentially identical interfacial microstructure. Evidence for diffusion of excitons from effectively narrow well regions to wider well regions is presented. 相似文献
105.
106.
To enhance the UV detectability of hydroxy fatty acids, p-nitrobenzyl (PNB) esters of twenty-two different monohydroxy fatty acids of various chain-lengths (C16-C22) and differing positional isomers were formed using O-(p-nitrobenzyl)-N,N-(diisopropyl)-isourea (PNBDI) as alkylating agent. Reversed-phase and adsorption high-performance liquid chromatography (HPLC) of the twenty-two monohydroxy fatty acid PNB esters were studied. The PNB group did not dominate the chromatographic properties of monohydroxy fatty acids and it did not interfere with the HPLC separation of positional isomers. PNBDI was, however, found to be less than ideal for formation of PNB derivatives of monohydroxy fatty acids because UV absorbing contaminants of PNBDI interfered with the HPLC analyses. 相似文献
107.
DiVittorio KM Johnson JR Johansson E Reynolds AJ Jolliffe KA Smith BD 《Organic & biomolecular chemistry》2006,4(10):1966-1976
The appearance of anionic phosphatidylserine (PS) in the outer monolayer of the plasma membrane is a universal indicator of the early/intermediate stages of cell apoptosis. The most common method of detecting PS on a cell surface is to use the protein annexin V; however, in certain applications there is a need for alternative reagents. Recent research indicates that rationally designed zinc 2,2'-dipicolylamine (Zn2+-DPA) coordination complexes can mimic the apoptosis sensing function of annexin V. Here, a series of fluorescently-labelled, tri- and pentapeptides with side chains containing Zn2+-DPA are prepared and shown to selectively bind to anionic vesicle membranes. Fluorescein-labelled versions of the peptides are used to detect apoptotic cells by fluorescence microscopy and flow cytometry. 相似文献
108.
Platinum-acetylide polymer based solar cells: involvement of the triplet state for energy conversion
Guo F Kim YG Reynolds JR Schanze KS 《Chemical communications (Cambridge, England)》2006,(17):1887-1889
Relatively efficient photovoltaic devices were fabricated using blends of a phosphorescent platinum-acetylide polymer and a fullerene (PCBM); involvement of the triplet excited state of the platinum-acetylide polymer in photoinduced charge transfer is believed to contribute to the device efficiency. 相似文献
109.
110.