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171.
Bojarski AJ Mokrosz MJ Duszyńska B Kozioł A Bugno R 《Molecules (Basel, Switzerland)》2004,9(3):170-177
Two sets of new o-methoxyphenylpiperazine (MPP; series a) and 1,2,3,4-tetrahydroisoquinoline (THIQ; series b) derivatives, containing various imide moieties derived from NAN190, were synthesized and evaluated in vitro for their ability to bind to the serotonin 5-HT(1A) and 5-HT(2A) receptors. All new derivatives from series a demonstrated high 5-HT(1A) affinities, whereas THIQ analogues were much less active. With respect to 5-HT(2A) receptors, three MPP derivatives presented moderate activity but the rest of the investigated compounds were practically inactive. The influence of changes in terminus geometry on 5-HT(1A) receptor affinity was analyzed in regard to model compounds NAN190and MM199. 相似文献
172.
173.
Stanislaw Penczek Ryszard Szymanski Andrzej Duda Jolanta Baran 《Macromolecular Symposia》2003,201(1):261-270
Polymerization of cyclic esters leads to (bio)degradable polymers of the increasing industrial importance. These polymerizations are of the living nature, although chain transfer to polymer with chain scission may cause deviations from the livingness and introduce structural differences (e.g. in end-groups), important for physical properties. Two different systems are discussed. In the first one two living macromolecules react one with another and reproduce two living macromolecules, retaining the same reactivities and the same end-groups. Polymerizations of ϵ-caprolactone and lactide belong to this category. On the other hand, polymerization of cyclic carbonates proceeds with chain transfer, in which disproportionation of the living chains takes place: from two living macromolecules one “dead” and one “doubly active” can be formed. Conditions of retaining the livingness in terms of the ratios of the rate constants of transfer, reinitiation, and propagation are discussed. 相似文献
174.
The absolute configuration of an α‐P stereogenic center in two diastereomeric O,O‐dialkyl α‐aminophosphonates ( 3 ), arising from an induced 1,3‐asymmetric phosphite addition to the CN bond of furfural‐derived Schiff bases ( 1 ), was established from single product 1H NMR data. Such spectra were interpreted with anisotropic shielding in relation to the AM1 and MNDO/d structures of 3 ; the former ones turned out to be closer to the obtained experimental results (1H NMR spectra of 3 , crystallographic database study). Since favored 3‐21G geometries of starting imines 1 were modeled as well, it was inferred that a stereochemical outcome of this reaction is governed by Cram selectivity. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:120–125, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10005 相似文献
175.
Two new chelating sorbents for metal ions were prepared by the impregnation of chemically modified silicas LiChroprep RP-8
and RP-18 with ion pairs composed of the cation of Aliquat 336 and the anion of Calcon. The sorbents were compared with an
analogous sorbent with a plain silica carrier containing the same ion pairs. A hypothesis for binding this ion pair by the
surfaces of the applied carriers was presented. A higher stability of the two sorbents in comparison with that of the plain
silica chelating sorbent was demonstrated. The sorbents obtained were applied for chromatographic separations of some chosen
mixtures of some metal ions and for additional purification of aqueous solutions of alkali metals from trace amounts of heavy
metals. The multiple use of the sorbents based on RP-8 and RP-18 in sorption–desorption processes of metal ions without deterioration
of their sorption capacities was demonstrated.
Received March 8, 2000. Revision March 5, 2001. 相似文献
176.
Alkyl 2‐chloro‐2,3‐epoxyalkanoates react with trialkyl phosphites to give mixtures of (E) and (Z) alkyl 2‐diethoxyphosphoryloxy‐2‐alkenoates instead of the expected alkyl 2‐oxo‐3‐dialkoxyphosphorylalkanoates. Thermal isomerization of the alkyl 2‐chloro‐2,3‐epoxyalkanoates to alkyl 3‐chloro‐2‐oxoalkanoates and subsequent Perkow reaction of the latter with trialkyl phosphites yields the same products but usually in different (E) to (Z) ratios. A likely mechanism for the unexpected reaction is discussed. © 2000 John Wiley & Sons, Inc. Heteroatom Chem 11:115–119, 2000 相似文献
177.
178.
A review of the results of studies on the structure, phase transitions and physical properties of alkylammonium halogenoantimonates (III) and bismuthates (III) is presented. The crystals of these compounds are characterized by a variety of anionic structures and show a number of phase transitions including those to polar phases. We concentrate here mainly on dielectric and pyroelectric properties, spontaneous polarization and DSC studies. The mechanism of the phase transitions is discussed based on the results of X-ray, dielectric relaxation, PMR, IR and R spectra studies gathered so far. A particular role is played by a reorientational motion of the alkylammonium cations. 相似文献
179.
This paper presents an investigation of the phase transitions and molecular dynamics of radicals in pyridinium tetrafluoroborate single crystals by CW-EPR combined with the Computer Resolution Enhancement Method. We present the advantages following from the computer method for enhancement of resolution by the example of applying it in the analysis of complex CW-EPR spectra of organic radicals. The method enabled determination of basic parameters such as spectroscopic splitting factor, hyperfine coupling constants and widths of individual spectral lines in CW-EPR spectra of pyridinium tetrafluoroborate recorded in a wide range of temperatures. Phase transitions and changes in molecular dynamics of radicals may imply changes in their electronic structure, which may affect the above-mentioned parameters of CW-EPR spectra. 相似文献
180.