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991.
Facile H2 heterolysis was found to be mediated by coordinatively unsaturated Cp*Ir and Cp*Rh thiolate complexes. The reaction of iridium complex is reversible, and the formation of an intermediary Ir-H/thiol complex was detected. The reversible conversion between thiolate complex+H2 and hydride complex+thiol provides an intriguing functional model of [NiFe] hydrogenase. 相似文献
992.
Uchiyama M Kobayashi Y Furuyama T Nakamura S Kajihara Y Miyoshi T Sakamoto T Kondo Y Morokuma K 《Journal of the American Chemical Society》2008,130(2):472-480
We present full details of our new methods for preparing functionalized benzynes with lithium di-alkyl(2,2,6,6-tetramethylpiperidino)zincate (R2Zn(TMP)Li) through deprotonative zincation as a key reaction. In this system, by choosing appropriate ligands for the zincate, either regioselective zincation of functionalized haloaromatics or the generation of substituted benzynes can be controlled in good yields with excellent chemoselectivity, using the same substrate. Zincation with (t)Bu2Zn(TMP)Li followed by electrophilic trapping or zincation with Me2Zn(TMP)Li followed by nucleophilic or diene trapping is shown to be a powerful tool for the chemoselective preparation of 1,2,3-/1,2,4-trisubstituted benzene derivatives. These methods offer far greater generality than previous methods for the synthesis of multifunctionalized benzenes. Computational/theoretical studies of the reaction mechanism of this unique benzyne formation indicated that preferential coordination of the dialkylzinc moiety of zincate to halogen is the reason for the reduced activation energy of the elimination, that is, for the formation of the benzyne. The role of the ligands on Zn in accelerating/decelerating the elimination is also discussed. 相似文献
993.
Sakamoto S Putalun W Tsuchihashi R Morimoto S Kinjo J Tanaka H 《Analytica chimica acta》2008,607(1):100-105
Plumbagin (PL; 5-hydroxy-2-methyl-1,4-naphthoquinone) is a natural compound mainly isolated from Plumbago zeylanica. This plant is distributed in Southeast Asia, and well known as Ayurvedic medicine in India for its medicinal properties. PL has been shown to have various pharmacological activities. We have successfully prepared monoclonal antibodies against PL, and developed an enzyme-linked immunosorbent assay (ELISA) system for determination of PL. 3-(5-Hydroxy-2-methyl-1,4-naphthoquinone-3-yl) propanoic acid was synthesized and purified to prepare PL-bovine serum albumin conjugate (PL-BSA), which was used as an immunogen. PL-BSA conjugate was administered into BALB/c male mice for production of monoclonal antibodies against PL. The monoclonal antibody against PL which is secreted from established hybridoma cell line 3A3 (MAb 3A3) has been proven to have highly-specific to PL resulting from cross-reactivities test. The range for calibration of PL by ELISA was 0.2-25 μg mL−1. Based on validation analysis, this analytical method by ELISA is a precise, accurate, and sensitive method for the determination of PL in plant. 相似文献
994.
Maruta T Saito T Inagaki M Shibata O Higuchi R 《Chemical & pharmaceutical bulletin》2005,53(10):1255-1258
A new glucocerebroside, linckiacerebroside A (1) and a known glucocerebroside S-2a-3 (2), have been isolated from the cerebroside molecular species obtained from the less polar fraction of the CHCl3/MeOH extract of the starfish Linckia laevigata, together with three pseudo homogeneous glucocerebroside, 3, 4, and 5. The structures of these cerebrosides were determined on the basis of chemical and spectroscopic evidence. 相似文献
995.
Kobayashi K Kobayashi N Ikuta M Therrien B Sakamoto S Yamaguchi K 《The Journal of organic chemistry》2005,70(2):749-752
The syntheses of various types of hexakis(4-functionalized-phenyl)benzenes 1 and hexakis[4-(4'-functionalized-phenylethynyl)phenyl]benzenes 2 by the cobalt-catalyzed cyclotrimerization of diarylacetylenes and by the Sonogashira coupling reaction of 1e with arylacetylenes, respectively, are described. X-ray crystallographic analysis showed that host 1e or 2f forms a 2-D network by unique I...I or CH...O=C interactions, respectively. 相似文献
996.
997.
998.
The new perovskite cuprate material Sr8CaRe3Cu4O24, which behaves ferrimagnetically and shows an unusually high Curie temperature (T(C) approximately 440 K), is found from density-functional theory calculation to display several surprising properties after hole doping or chemical substitution: (1) Half metal (HM) is realized by replacing Re with W or Mo while T(C) remains high; (2) hole-doped Sr8CaRe3Cu4O24 is also HM with high T(C). Moreover, we find that the O atoms will carry a large magnetic moment after hole doping, which is in sharp contrast to the generally accepted concept that magnetism in solids requires partially filled shells of d or f electrons in cations. The material Sr8CaRe3Cu4O24 is therefore expected to provide a very useful platform for material design and development. 相似文献
999.
A numerical investigation of group birefringence is carried out on a recently reported highly birefringent hollow-core photonic bandgap fiber by use of an efficient vector finite-element method. The hollow fiber core has an area as large as that of approximately four airholes in the cladding region and assumes a rhombic shape with round corners, and the airholes in the cladding region are hexagonal and provide a high air-filling fraction. Numerical results show very high group birefringence of the order of 10(-2) and phase birefringence of the order of 10(-3). 相似文献
1000.
We propose and demonstrate a novel type of bending-insensitive single-mode hole-assisted fiber that has a doped core and two layers of holes with two different airhole diameters. The fiber has a 9.3 microm mode field diameter, a bending loss of 0.011 dB/turn at 1.55 microm for a bending diameter of 10 mm, and a cutoff wavelength below 1.1 microm. The fiber can be fusion spliced to a conventional single-mode fiber with low loss. 相似文献