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11.
Structure Elucidator: a versatile expert system for molecular structure elucidation from 1D and 2D NMR data and molecular fragments 总被引:2,自引:0,他引:2
Elyashberg ME Blinov KA Williams AJ Molodtsov SG Martin GE Martirosian ER 《Journal of chemical information and computer sciences》2004,44(3):771-792
StrucEluc is an expert system that allows the computer-assisted elucidation of chemical structures based on the inputs of a series of spectral data including 1D and 2D NMR and mass spectra. The system has been enabled to allow a chemist to utilize fragments stored in a fragment database as well as user-defined fragments submitted by the chemist in the structure elucidation process. The association of fragments in this way has been shown to dramatically speed up the process of structure generation from 2D NMR data and has helped to minimize or eliminate the need for user intervention thereby further enabling the vision of automated elucidation. The use of fragments has frequently transformed very difficult 2D NMR elucidation challenges into easily solvable tasks. A strategy to utilize molecular fragments has been developed and optimized based on specific challenging examples. This strategy will be described here using real world examples. Experience gained by solving more than 150 structure elucidation problems from a variety of literature sources is also reviewed in this work. 相似文献
12.
A. V. Zaitsev G. V. Kozlova V. Yu. Borovkov A. Yu. Krylova A. L. Lapidus V. B. Kazanskii 《Russian Chemical Bulletin》1990,39(11):2394-2396
Diffuse scattering IR spectroscopy was used to study the 10% Co/Al2O3 catalyst for the synthesis of aliphatic hydrocarbons from CO and H2. Ionic and metallic cobalt forms were identified in the IR spectroscopy. The adsorption of CO on these forms is accompanied by the appearance of linear and bridged complexes. After prolonged treatment of the catalyst by a CO + 2H2 mixture, the ions and surface of metallic cobalt remain available for the adsorption of CO. Modification of the surface of metallic cobalt occurs upon the action of the reaction medium. This modification is seen in a bathochromic displacement of the IR bands for the adsorbed and linear CO forms. This displacement is accompanied by a reduction in the strength of the metal-carbon bond in the Coo-CO complex.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2640–2643, November, 1990. 相似文献
13.
Eneyskaya EV Ivanen DR Shabalin KA Kulminskaya AA Backinowsky LV Brumer Iii H Neustroev KN 《Organic & biomolecular chemistry》2005,3(1):146-151
Transglycosylation catalyzed by a beta-D-xylosidase from Aspergillus sp. was used to synthesize a set of 4-methylumbelliferyl (MU) beta-1-->4-D-xylooligosides having the common structure [beta-D-Xyl-(1-->4)]2-5-beta-D-Xyl-MU. MU xylobioside synthesized chemically by the condensation of protected MU beta-D-xylopyranoside with ethyl 2,3,4-tri-O-acetyl-1-thio-beta-D-xylopyranoside was used as a substrate for transglycosylation with the beta-D-xylosidase from Aspergillus sp. to produce higher MU xylooligosides. The structures of oligosaccharides obtained were established by 1H and 13C NMR spectroscopy and electrospray tandem mass spectrometry. MU beta-D-xylooligosides synthesized were tested as fluorogenic substrates for the GH-10 family beta-D-xylanase from Aspergillus orizae and the GH-11 family beta-D-xylanase I from Trichoderma reesei. Both xylanases released the aglycone from MU xylobioside and the corresponding trioside. With substrates having d.p. 4 and 5, the enzymes manifested endolytic activities, splitting off MU, MUX, and MUX2 primarily. 相似文献
14.
E. Yu. Vol'f T. Yu. Solov'eva M. M. Vartanyan L. Yu. Brezhnev A. L. Lapidus 《Russian Chemical Bulletin》1989,38(11):2356-2358
The synthesis of 3-formyl derivatives of the tetrahydrofuran series was carried out by hydroformylation of 2,3-dihydrofuran and 2,5-dimethoxy-2,5-dihydrofuran in the presence of HRh(CO)(PPh3)3. The influence of the temperature, pressure, catalyst concentration, and the nature of the solvent on the conversion of dihydrofuran, the composition of aldehydes obtained and the selectivity of their formation was investigated.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2569–2571, November, 1989. 相似文献
15.
Kolen'ko YV Kovnir KA Gavrilov AI Garshev AV Meskin PE Churagulov BR Bouchard M Colbeau-Justin C Lebedev OI Van Tendeloo G Yoshimura M 《The journal of physical chemistry. B》2005,109(43):20303-20309
Mesoporous nanosized TiO2 and Zn(x)Ti(1-x)O(2-x) solid solution having a Zn content below 10 mol % with a particles size between 13 and 17 nm are prepared by a template-free sol-gel method followed by high-temperature supercritical drying in 2-propanol. The structural, textural, and electronic properties of the obtained nanomaterials are methodically investigated by using XRD, SEM, TEM, ED, HREM, EDX, ICP-OES, N(2) adsorption-desorption, Raman spectroscopy, and diffuse reflectance UV-vis spectroscopy. It is shown that the proposed synthesis technique leads to the formation of a Zn(x)Ti(1-x)O(2-x) solid solution based on the anatase crystal structure rather than a two-phase sample. High-resolution electron microscopy and electron diffraction indicate that the distribution of zinc atoms over the anatase structure does not lead to a considerable deformation of the crystal structure. 相似文献
16.
A. L. Lapidus S. V. Yushin O. I. Mishchenko A. A. Vedenyapin L. T. Kondrat'ev 《Russian Chemical Bulletin》1991,40(7):1499-1501
The use of an Ni-Pd/Al2O3 catalyst in the synthesis of C1-C4 hydrocarbons from CO and H2 permits us to increase the selectivity and total yield of these products by a factor of 1.5–2.0 relative to the corresponding nickel and palladium catalysts. The optimal temperatures and CO/H2 ratios for obtaining hydrocarbons were determined. A structure was proposed for the active sites of the bimetallic catalyst.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1689–1691, July, 1991. 相似文献
17.
A. L. Lapidus Z. Novak M. M. Savel'ev B. Lyukke T. Zimmerman S. D. Pirozhkov Kh. É. Manek S. D. Sominskii L. F. Rar 《Russian Chemical Bulletin》1990,39(8):1545-1547
Catalysts of 4.5% Co- 0.1% Rh- 5:10% Cu/TiO
2 display high activity in the synthesis from CO and H2 of a mixture of hydrocarbons and alcohols at 250–300°C and pressures of 0.1–6.0 MPa; these catalysts are more selective than traditional Co catalysts with respect to alcohol formation.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1707–1709, August, 1990. 相似文献
18.
Watzke A Brunsveld L Durek T Alexandrov K Rak A Goody RS Waldmann H 《Organic & biomolecular chemistry》2005,3(7):1157-1164
Rab/Ypt guanosine triphosphatases (GTPases) represent a family of key membrane traffic regulators in eukaryotic cells. For their function Rab/Ypt proteins require double modification with two covalently bound geranylgeranyl lipid moieties at the C-terminus. Generally, prenylated proteins are very difficult to obtain by recombinant or enzymatic methods. We generated prenylated RabGTPases using a combination of chemical synthesis and protein engineering. This semi-synthesis depends largely on the availability of functionalized prenylated peptides corresponding to the proteins' native structure or modifications. We developed solution phase and solid phase strategies for the generation of peptides corresponding to the prenylated C-terminus of Rab7 GTPase in preparative amounts enabling us to crystallize the mono-prenylated Ypt1:RabGDI complex. The structure of the complex provides a structural basis for the ability of RabGDI to inhibit the release of nucleotide by Rab proteins and a molecular basis for understanding a RabGDI mutant that causes mental retardation in humans. 相似文献
19.
Metallosilicates as supports of Co catalysts for the synthesis of liquid hydrocarbons from CO and H2
A. Yu. Krylova A. L. Lapidus M. P. Kapur V. I. Vershinin V. B. Mel'nikov 《Russian Chemical Bulletin》1993,42(3):432-434
The effect of the nature of the silicate support on the activity and selectivity of 10%. Co/M silicate catalysts (where M=Cu, Zn, Ce, Ti, Hf, La, Al, Zr, Co, Mg) in the synthesis of hydrocarbons from CO and H2 has been established. Co and Zr catalysts have been shown to provide the highest catalytic efficiency. The yield of liquid hydrocarbons in their presence exceeds 120 g m–3.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 480–482, March, 1993. 相似文献
20.