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排序方式: 共有212条查询结果,搜索用时 15 毫秒
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Teplý F Stará IG Starý I Kollárovic A Saman D Vyskocil S Fiedler P 《The Journal of organic chemistry》2003,68(13):5193-5197
A nonphotochemical synthetic route to 3-hexahelicenol is reported. It involves a key [2+2+2] cycloisomerization of CH(3)O-substituted triyne that is readily available from 1-methoxy-3-methylbenzene and 1-bromo-2-(bromomethyl)naphthalene. Further functional group transformations led to 3-CO(2)CH(3), 3-NH(2), 3-PPh(2), and 3-SC(O)N(CH(3))(2) substituted hexahelicenes. 相似文献
3.
Vyskocil S Meca L Tislerová I Císarová I Polásek M Harutyunyan SR Belokon YN Stead RM Farrugia L Lockhart SC Mitchell WL Kocovský P 《Chemistry (Weinheim an der Bergstrasse, Germany)》2002,8(20):4633-4648
The title binaphthyls 19 and 26, which are the positional isomers of 2-methoxy-2'-(diphenylphosphino)-1,1'-binaphthyl (MOP, 19) and 2-amino-2'-hydroxy-1,1'-binaphthyl (NOBIN, 26), have been synthesized by Suzuki coupling as the key step (10 + 15-->18), followed by functional group transformations, involving C-P and C-N bond formation (18-->19 and 18-->23). Racemic intermediate 22 was resolved by co-crystallization with N-benzylcinchonidinium chloride and the absolute configuration determined by X-ray crystallography. These novel binaphthyls are configurationally stable and, as such, potentially usable as chiral ligands in asymmetric reactions. Michael addition of the glycine-derived enolate 40 to methyl acrylate, carried out in the presence of (R)-(-)-27 as the chiral phase-transfer catalyst, afforded L-glutamic acid (S)-(+)-43 of 92% ee (after hydrolysis of the primary product). 相似文献
4.
Meersman F Dirix C Shipovskov S Klyachko NL Heremans K 《Langmuir : the ACS journal of surfaces and colloids》2005,21(8):3599-3604
In a cellular environment, the presence of macromolecular cosolutes and membrane interfaces can influence the folding-unfolding behavior of proteins. Here we report on the pressure stability of alpha-chymotrypsin in the ternary system bis(2-ethylhexyl)sodium sulfosuccinate-octane-water using FTIR spectroscopy. The ternary system forms anionic reverse micelles which mimic cellular conditions. We find that inclusion of a single protein molecule in a reverse micelle does not alter its conformation. When pressurized in bulk water, alpha-chymotrypsin unfolds at 750 MPa into a partially unfolded structure. In contrast, in the ternary system, the same pressure increase induces a random coil-like unfolded state, which collapses into an amorphous aggregate during the decompression phase. It is suggested that the unfolding pathway is different in a cell-mimicking environment due to the combined effect of multiple factors, including confinement. A phase transition of the reverse micellar to the lamellar phase is thought to be essential to provide the conditions required for unfolding and aggregation, though the unfolding is not a direct result of the phase transition. Our observations therefore suggest that membranes may cause the formation of alternative conformations that are more susceptible to aggregation. 相似文献
5.
Stepan Boitsov Jon Songstad Karl W. Trnroos 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(2):o66-o68
4‐(Trifluoromethyl)benzonitrile, C8H4F3N, at 123 K contains molecules linked together through one C—H?F bond and two C—H?N hydrogen bonds into sheets that are further crosslinked to form a dense two‐dimensional network without π?π ring interactions. The aromatic ring is slightly deformed due to the two para‐related electronegative groups. 相似文献
6.
Stepan S. Basok Gabriele Bocelli Eduard V. Ganin Marina S. Fonari Yurii A. Simonov 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(1):o50-o52
In the title compound, 2C8H18NO3+·2C7H6NO2−·3H2O, proton transfer occurs from the carboxylic acid group of the 4‐aminobenzoic acid (PABA) molecule to the amine group of the macrocycle, resulting in the formation of a salt‐like adduct. The anions are combined into helical chains which are further bound by the water molecules into sheets. The macrocyclic cations are situated between these layers and are bound to the anions both directly and via bridging water molecules. The structure exhibits a diverse system of hydrogen bonding. 相似文献
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Petr Kluson Stepan Kment Magdalena Morozova Pavel Dytrych Stanislav Hejda Morwenna Slater Zdenek Hubicka Josef Krysa 《Chemical Papers》2012,66(5):446-460
Chemistry and physics of thin semiconducting layers of various types are subjects of intense research. Especially when nanotechnology
methods such as self-assembly are involved, amazing structural and/or functional properties may appear. Also modern physical
methods using variously organized plasma arrangements are able to produce uniform structures with distinctive functionality.
In this review, based virtually on our own work, discussions on the preparation, structure, morphology, and function of titanium(IV)
oxide nanoscopic thin films are presented. It was shown that structurally and functionally similar titanium(IV) oxide films
can be prepared via completely different preparation techniques. Function tests were arranged as “primary”, covering the assessment
of the light induced charge separation efficiency, and “secondary”, based on photocatalytic surface oxidations. 相似文献
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