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41.
D. R. Phillips V. T. Hamilton D. J. Jamriska M. A. Brzezinski 《Journal of Radioanalytical and Nuclear Chemistry》1995,195(2):251-261
Heteropolymolybdic acid species of a variety of elements bind to Sephadex (dextran cross-linked by epichlorohydrin). Solution pH can be used as a variable to influence the formation of heteropolymolybdates and thus their affinity for Sephadex. Therefore this material may be used to chromatographically separate certain elements which have been reacted with molybdate in solution. In this paper we report the measurement of distribution coefficients on Sephadex for heteropolymolybdates of As, P, Ge, Si, and Se for solutions of varying pH. We also describe the application of the technique to the recovery of32Si from proton-irradiated KCl targets and68Ge from proton-irradiated molybdenum targets. 相似文献
42.
Bogumil Brzezinski 《Magnetic resonance in chemistry : MRC》1979,12(8):450-453
The 1H NMR spectra of perchlorates of N-(pyridyl)amides of 6-methylpicolinic acid N-oxide (PYAP) in CD3CN at 100 MHz show two proton signals belonging to two distinct intramolecular hydrogen bonds. The position of these signals is independent of concentration and temperature. That of the proton of the N? H ?O bond in PYAP is shifted to still lower field than in N-(pyridyl)amides of 6-methylpicolinic acid N-oxide (PYA) due to the inductive effect of the pyridine cation and the formation of another intramolecular hydrogen N+? H ?O bond. The proton of the N+? H ?O bond interacts strongly with its environment and is highly sensitive to traces of water. Presumably, water leads to dissociation of the intramolecular bond. 相似文献
43.
44.
G. Schroeder B. Gierczyk V. Rybachenko B. Brzezinski 《Journal of Molecular Structure》2000,526(1-3):159-163
The heats of reactions between the acyclic and cyclic macro-compounds are determined. The values can be used as a measure of the donor abilities of the macro ligands. Formation of two types of complexes between the macro compounds and SbCl5 is established. The acyclic macro-compounds form 1:1 complexes, whereas the macrocyclic compounds only 1:2 complexes. 相似文献
45.
46.
Zbigniew Burdak Marek Kosiek Patryk Pagacz Marek Słociński 《Integral Equations and Operator Theory》2014,79(1):107-122
Pairs (V, V′) of commuting, completely non doubly commuting isometries are studied. We show, that the space of the minimal unitary extension of V (denoted by U) is a closed linear span of subspaces reducing U to bilateral shifts. Moreover, the restriction of V′ to the maximal subspace reducing V to a unitary operator is a unilateral shift. We also get a new hyperreducing decomposition of a single isometry with respect to its wandering vectors which strongly corresponds with Lebesgue decomposition. 相似文献
47.
Garcia A Bakus RC Zalar P Hoven CV Brzezinski JZ Nguyen TQ 《Journal of the American Chemical Society》2011,133(8):2492-2498
The properties and function of an anionic conjugated polyelectrolyte (CPE)-containing ion-conducting polyethylene oxide pendant (PF(PEO)CO(2)Na) as electron injection layers (EILs) in polymer light-emitting diodes (PLEDs) are investigated. A primary goal was to design a CPE structure that would enable acceleration of the device temporal response through facilitation of ion motion. Pristine PLEDs containing PF(PEO)CO(2)Na exhibit luminance response times on the order of tenths of seconds. This delay is attributed to the formation of ordered structures within the CPE film, as observed by atomic force microscopy. Complementary evidence is provided by electron transport measurements. The ordered structures are believed to slow ion migration within the CPE EIL and hence result in a longer temporal response time. It is possible to accelerate the response by a combination of thermal and voltage treatments that "lock" ions within the interfaces adjacent to PF(PEO)CO(2)Na. PLED devices with luminance response times of microseconds, a 10(5) fold enhancement, can therefore be achieved. Faster luminance response time opens up the application of PLEDs with CPE layers in display technologies. 相似文献
48.
Corrigendum: Highly Enantioselective Hydrogenation of 1‐Alkylvinyl Benzoates: A Simple,Nonenzymatic Access to Chiral 2‐Alkanols
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49.
Przybylski P Kira J Schroeder G Brzezinski B Bartl F 《The journal of physical chemistry. A》2008,112(35):8061-8069
Stability constants of complexes formed by gossypol and by ten of its Schiff bases with Ag (+) cations were determined by the potentiometric method. The potentiometric and ESI MS experiments indicate the formation of AgL (+) and Ag 2L (2+) complexes between the Schiff bases G1-G7 and Ag (+) cations as well as the formation of AgL (+), Ag 2L (2+), AgL 2 (+) and Ag 3L 2 (3+) complexes between the Schiff bases G8-G10 and Ag (+) cations. The highest stability constant was found for the AgL (+) complex of G8 Schiff base and the lowest one for the AgL (+) complex of G molecule. The (13)C NMR spectra of mixtures between G and AgClO 4 as well as G1-G10 and AgClO 4 indicate that the complexation of the Ag (+) cations is exclusively realized by the aldehyde-aldehyde tautomer of gossypol and by the enamine-enamine form of gossypol Schiff bases, respectively. We show that the main coordination sites for the Ag (+) metal cations are either the oxygen or the nitrogen atoms of the amine parts of the Schiff bases of gossypol. The energetically most favorable structures of the Ag (+) complexes with gossypol (G) or with the gossypol Schiff bases (G1-G10) were calculated and visualized by the AM1d method at an semiempirical level of theory. 相似文献
50.
Lasalocid acid is an ionophore able to carry protons and cations through the cell membrane. Its 2-naphthylmethyl ester (NAFB) and its complexes with Li+, Na+ and K+ cations were synthesized and their structures were studied by ESI-MS, 1H NMR, 13C NMR, FTIR and PM5 methods. The ESI-MS spectra indicate that NAFB forms stable complexes with Li+, Na+ and K+ cations of exclusively 1:1 stoichiometry and that the complexation of Li+ cations by NAFB is favoured. The NMR and FTIR spectra indicate that the oxygen atom of the ketone group of the NAFB molecule is involved in the coordination of the cations, and the strength of this process is dependent on the type of cation. We find that the intramolecular O(3)?CH···O(2) hydrogen bond in NAFB and its complexes is partially broken in acetonitrile solution and that this process is independent of the type of cation. The PM5 semiempirical calculations allow visualisation of all structures and determination of the hydrogen bond parameters. 相似文献