排序方式: 共有197条查询结果,搜索用时 15 毫秒
41.
Irmukhametova GS Fraser BJ Keddie JL Mun GA Khutoryanskiy VV 《Langmuir : the ACS journal of surfaces and colloids》2012,28(1):299-306
PEGylated organosilica nanoparticles have been synthesized through self-condensation of (3-mercaptopropyl)trimethoxysilane in dimethyl sulfoxide into thiolated nanoparticles with their subsequent reaction with methoxypoly(ethylene glycol) maleimide. The PEGylated nanoparticles showed excellent colloidal stability over a wide range of pH in contrast to the parent thiolated nanoparticles, which have a tendency to aggregate irreversibly under acidic conditions (pH < 3.0). Due to the presence of a poly(ethylene glycol)-based corona, the PEGylated nanoparticles are capable of forming hydrogen-bonded interpolymer complexes with poly(acrylic acid) in aqueous solutions under acidic conditions, resulting in larger aggregates. The use of hydrogen-bonding interactions allows more efficient attachment of the nanoparticles to surfaces. The alternating deposition of PEGylated nanoparticles and poly(acrylic acid) on silicon wafer surfaces in a layer-by-layer fashion leads to multilayered coatings. The self-assembly of PEGylated nanoparticles with poly(acrylic acid) in aqueous solutions and at solid surfaces was compared to the behavior of linear poly(ethylene glycol). The nanoparticle system creates thicker layers than the poly(ethylene glycol), and a thicker layer is obtained on a poly(acrylic acid) surface than on a silica surface, because of the effects of hydrogen bonding. Some implications of these hydrogen-bonding-driven interactions between PEGylated nanoparticles and poly(acrylic acid) for pharmaceutical formulations are discussed. 相似文献
42.
Andriy V. Tymtsunik Vitaliy A. BilenkoYevhen M. Ivon Oleksandr O. Grygorenko Igor V. Komarov 《Tetrahedron letters》2012,53(30):3847-3849
The synthesis of the Boc derivative of a novel member of the cyclopropane-modified proline library, Boc-protected 5-azaspiro[2.4]heptane-6-carboxylic acid, is reported. The synthesis was performed in six steps starting from (2S,4R)-4-hydroxyproline using a modified Simmons-Smith reaction as the key step. The reaction conditions for all the steps were carefully selected to avoid racemization at the chiral centers in the intermediates and the final product. 相似文献
43.
Wickrama Arachchilage AP Wang F Feyer V Plekan O Prince KC 《The Journal of chemical physics》2012,136(12):124301
We have investigated the electronic structure of three cyclic dipeptides: cyclo(Histidyl-Glycyl) (cHisGly), cyclo(Tyrosyl-Prolyl) (cTyrPro), and cyclo(Phenylalanyl-Phenylalanyl) (cPhePhe) in the vapor phase, by means of photoemission spectroscopy and theoretical modeling. The last compound was evaporated from the solid linear dipeptide, but cyclised, losing water to form cPhePhe in the gas phase. The results are compared with our previous studies of three other cyclopeptides. Experimental valence and core level spectra have been interpreted in the light of calculations to identify the basic chemical properties associated with the central diketopiperazine ring, and with the additional functional groups. The valence spectra are generally characterized by a restricted set of outer valence orbitals separated by a gap from most other valence orbitals. The theoretically simulated core and valence spectra of all three cyclic dipeptides agree reasonably well with the experimental spectra. The central ring and the side chains act as independent chromophores whose spectra do not influence one another, except for prolyl dipeptides, where the pyrrole ring is fused with the central ring. In this case, significant changes in the valence and core level spectra were observed, and explained by stronger hybridization of the valence orbitals. 相似文献
44.
Tymtsunik AV Bilenko VA Kokhan SO Grygorenko OO Volochnyuk DM Komarov IV 《The Journal of organic chemistry》2012,77(2):1174-1180
An approach to the synthesis of 1-alkyl-5-((di)alkylamino)tetrazoles by nucleophilic substitution in 1-alkyl-5-sulfonyltetrazoles with anions generated from the primary or secondary amines was developed. Tolerance of the method to the presence of some functional groups (i.e., protected amine) in both components of the reaction was demonstrated. Obtained tetrazoles are promising building blocks for the design of peptide surrogates, in particular, for replacement approaches of alkyl urea derivatives. 相似文献
45.
Joseph P. Cook Glenn W. Goodall Olga V. Khutoryanskaya Vitaliy V. Khutoryanskiy 《Macromolecular rapid communications》2012,33(4):332-336
It has been found that hydrogels may be formed by microwave irradiation of aqueous solutions containing appropriate combinations of polymers. This new method of hydrogel synthesis yields sterile hydrogels without the use of monomers, eliminating the need for the removal of unreacted species from the final product. Results for two particularly successful combinations, poly(vinyl alcohol) with either poly(acrylic acid) or poly(methylvinylether‐alt‐maleic anhydride), are presented. Irradiation using temperatures of 100–150 °C was found to yield hydrogels with large equilibrium swelling degrees of 500–1000 g g−1. Material leached from both types of hydrogel shows little cytotoxicity towards HT29 cells. 相似文献
46.
M Ahmed A Ganesan F Wang V Feyer O Plekan KC Prince 《The journal of physical chemistry. A》2012,116(33):8653-8660
X-ray photoelectron spectra of the core and valence levels of the fundamental building blocks of β-lactam antibiotics have been investigated and compared with theoretical calculations. The spectra of the compounds 2-azetidinone and the 2- and 4-isomers of thiazolidine-carboxylic acid are interpreted in the light of theoretical calculations. The spectra of the two isomers of thiazolidine-carboxylic acid are rather similar, as expected, but show clear effects due to isomerization. Both isomers are analogues of proline, which is well-known to populate several low energy conformers in the gas phase. We have investigated the low energy conformers of thiazolidine-4-carboxylic acid theoretically in more detail and find some spectroscopic evidence that multiple conformers may be present. The measured valence levels are assigned for all three compounds, and the character of the frontier orbitals is identified and analyzed. 相似文献
47.
Ivanets Andrei Milyutin Vitaliy Shashkova Irina Kitikova Natalja Nekrasova Natalya Radkevich Artsiom 《Journal of Radioanalytical and Nuclear Chemistry》2020,324(3):1115-1123
Journal of Radioanalytical and Nuclear Chemistry - In this paper, we studied the features of stable and radioactive Cs(I), Sr(II) and Co(II) ions sorption on Ti–Ca–Mg phosphates. The... 相似文献
48.
Yanilkin Vitaliy V. Fazleeva Rezeda R. Nasretdinova Gulnaz R. Osin Yury N. Gubaidullin Aidar T. Ziganshina Аlbina Yu 《Journal of Solid State Electrochemistry》2020,24(4):829-842
Journal of Solid State Electrochemistry - Efficient two-step electrosynthesis of xCoO–yCo(OH)2 (CoOxHy)-supported silver nanoparticles (AgNPs) is carried out in N,N-dimethylformamide (DMF)... 相似文献
49.
Grigoriy A. Mun Vitaliy V. Khutoryanskiy Zauresh S. Nurkeeva Perizat I. Urkimbaeva Daulet Zhunuspaev 《Journal of Polymer Science.Polymer Physics》2004,42(14):2625-2632
Amphiphilic random copolymers based on vinyl ether of ethylene glycol and vinyl butyl ether as well as their polycomplexes with poly(acrylic acid) were studied as polymeric reagents for the stabilization of water/n‐hexane emulsions. The emulsion stability strongly depended on the content of vinyl butyl ether in the copolymers as well as their concentration in solution. The more hydrophobic copolymers stabilized emulsions more efficiently. An increase in the temperature and the addition of inorganic salts reduced the emulsion lifetime. The formation of interpolymer complexes between the copolymers and poly(acrylic acid) significantly influenced the stability of the emulsions. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2625–2632, 2004 相似文献
50.
Julia I. Nelina-Nemtseva Anna V. Gulevskaya Vitaliy V. Suslonov Alexander D. Misharev 《Tetrahedron》2018,74(10):1101-1109
π-Deficient ethynyl hetarenes were used as dipolarophiles in a 1,3-dipolar cycloaddition reaction with azomethine imines (2-arylidene-5-oxopyrazolidin-2-ium-1-ides). Both CuI-catalyzed and catalyst-free thermally induced reactions proceeded with high regioselectivity providing 6-hetaryl-5-aryl-2,3-dihydropyrazolo[1,2-a]pyrazol-1(5H)-ones in moderate to excellent yields. The ethynyl hetarenes (pyridines, pyrazines, quinoxalines, pteridines and pyrimido[4,5-c]pyridazines) with ortho-methyl, ortho-cyano and ortho-alkynyl substituents were applicable to this reaction. 1,3-Dipolar cycloaddition reactions of alkynyl hetarenes with azomethine imines or other 1,3-dipole reagents can be considered as an alternative synthetic approach to heterobiaryls. 相似文献