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931.
The super silyl group governs high diastereoselectivity and yields for a sequential aldol-polyhalomethyllithium addition reaction. This unique silyl group is necessary to obtain the diastereoselectivities associated with this sequential reaction, capable of generating two new stereocenters. Alpha-polyhalomethylcarbinols are generated with the simple and inexpensive dihalomethanes and trihalomethanes. 相似文献
932.
Shimakoshi H Baba T Iseki Y Aritome I Endo A Adachi C Hisaeda Y 《Chemical communications (Cambridge, England)》2008,(25):2882-2884
A heavy atom, bromine, was directly substituted into the porphycene macrocycle to promote intersystem crossing by way of spin-orbit coupling. The singlet oxygen production ability of the porphycene is dramatically enhanced, and the highest value of 0.95 for the quantum yield of singlet oxygen generation (PhiDelta) was obtained for the dibrominated porphycene by visible light excitation. 相似文献
933.
A novel composite of vinyl group functionalized multiwalled carbon nanotubes (MWCNTs) molecularly imprinted polymer (MIP) was synthesized and applied as a molecular recognition element to construct an electrochemical sensor for parathion-methyl in this paper. The special molecular recognition properties of parathion-methyl mainly dominated by π-π, p-π interaction and hydrogen bonding formed among functional monomer, template and matrix. A series of electrochemical experiment results proved that the prepared material had good adsorption capacity and fast mass transfer rate to parathion-methyl. The good selectivity of the sensor allowed fine discrimination between parathion and paraoxon, which had similar structures to parathion-methyl. The response of the MIPs was linearly proportional to the concentration of parathion-methyl over the range of 2.0 × 10(-7) to 1.0 × 10(-5) mol L(-1) with a lower detection limit of 6.7 × 10(-8) mol L(-1) (S/N = 3). This sensor was also applied in the detection of parathion-methyl in pear and cucumber with average recoveries of between 94.9% and 106.2% (RSD < 5%) being obtained. The results mentioned above show that the novel electrochemical sensor is an ideal device for the real-time determination of parathion-methyl in real samples. 相似文献
934.
A one-pot, three-component coupling was accomplished via the nucleophilic addition of an alkylsamarium(III) species to isocyanides and the subsequent addition of the resultant imidoyl samarium(III) species to isocyanates under mild conditions for the formation of α-iminocarboxamides. The developed sequential C-C bond-forming procedure enabled the rapid synthesis of the α-iminocarboxamides in good to excellent yields from readily available starting materials. 相似文献
935.
Hegazy ME Matsuda H Nakamura S Yabe M Matsumoto T Yoshikawa M 《Chemical & pharmaceutical bulletin》2012,60(3):363-370
The methylene chloride-methanol (1?:?1) extract from the air-dried aerial parts of wild Pulicaria undulata collected in North Sinia, Egypt, showed inhibitory effects on lipopolysaccharide (LPS)-induced production of nitric oxide (NO) in RAW264.7 macrophages. From the extract, three new sesquiterpenes named 5α-hydroperoxyivalin, 8-epi-xanthanol, and 8-epi-isoxanthanol were isolated together with four known sesquiterpenes. The structure of each new sesquiterpenes was determined on the basis of physicochemical and chemical evidence. In addition, all the sesquiterpenoids significantly inhibited the production of NO. Ivalin (IC50=2.0?μM) and 2α-hydroxyalantolactone (1.8?μM) showed particularly strong inhibitory effects, but had strong cytotoxic effects as well. Furthermore, ivalin and 2α-hydroxyalantolactone concentration-dependently reduced inducible NO synthase (iNOS) protein levels in RAW264.7 cells. 相似文献
936.
Liu L Sham TK Hayashi H Kanai N Takehara Y Kawamura N Mizumaki M Gordon RA 《The Journal of chemical physics》2012,136(19):194501
We report a resonant inelastic x-ray scattering (RIXS) study of crystalline CeB(6). Ce L(α1,2) RIXS was measured with excitation energies resonant with the Ce L(3)-edge. A lifetime-broadening suppressed x-ray absorption near-edge structure (LBS-XANES), which successfully reproduced the L(α1,2) RIXS spectra over wide ranges of excitation and emission energies, was simulated using the SIM-RIXS program. A pre-edge structure in the LBS-XANES can be resolved, and many-body effects were suggested in the L(α1,2) RIXS around the Ce L(3)-edge energy. No convincing signs of Ce (II) or Ce (IV) states were observed in the LBS-XANES. Ce L(γ4) RIXS was measured at 302 K and 28 K with excitation energies across the Ce L(1)-edge. The interactions of p-valence electrons between Ce and B(6) were found to be considerably small, regardless of temperature. Thus, the electronic state of CeB(6) was concluded to be suitably described as a nominally Ce(4f(1))(3+)(e(-))(B(6))(2-) system with some hybridization among all valence orbitals of Ce and B. 相似文献
937.
Numerous antibodies have been developed and validated in recent years, and show promise for use in novel functional protein assays. Such assays would be an alternative to pre-existing comprehensive assays, such as DNA microarrays. Antibody microarrays are thought to represent those functional protein assays. While a variety of attempts have been made to apply DNA microarray technology to antibody microarrays, a fully optimized protocol has not been established. We have been conducting a project to comprehensively produce antibodies against mouse KIAA ("KI" stands for "Kazusa DNA Research Institute" and "AA" are reference characters) proteins. Using our library of antibodies, we established a novel antibody microarray format that utilizes surface plasmon resonance (SPR) technology. A label-free real-time measurement of protein expression in crude cell lysates was achieved by direct readout of the bindings using SPR. Further refinement of the antibody microarray format enabled us to detect a smaller quantity of target proteins in the lysate without the bulk effect. In this review, we first summarize available antibody array formats and then describe the above-mentioned format utilizing updated SPR technology. 相似文献
938.
The Pd(0)-mediated rapid coupling of methyl iodide with an excess of alkenyltributylstannane was examined with the aim of incorporating a short-lived 11C-labeled methyl group into a biologically significant organic compound with a 1-methylalkene unit for the synthesis of a PET tracer. Four sets of reaction conditions (A-D) were used, all performed in DMF at 60 degrees C for 5 min. Condition B, using CH3I/stannane/Pd2(dba)3/P(o-tolyl)3/CuCl/K2CO3 (1:40:0.5:4-6:2:5), works well in almost all cases. Condition D, using CH3I/stannane/Pd2(dba)3/P(o-tolyl)3/CuX (X = Br, Cl, or I)/CsF (1:40:0.5-5:2-20:2-20:5-50), shows the best results with regard to general applicability to tin substrates, affording the corresponding methylated product in >90% yield based on consumption of methyl iodide. P(t-Bu)2Me was less effective than P(o-tolyl)3, particularly for alpha,beta-unsaturated carbonyl substrates. No regio- or stereoisomerization occurred under these reaction conditions. The efficiency of the protocol was demonstrated by synthesis of an 11C-methylated compound. 相似文献
939.
Preferential destruction of metallic single-walled carbon nanotubes by laser irradiation 总被引:2,自引:0,他引:2
Huang H Maruyama R Noda K Kajiura H Kadono K 《The journal of physical chemistry. B》2006,110(14):7316-7320
Upon laser irradiation in air, metallic single-walled carbon nanotubes (SWNTs) in carbon nanotube thin film can be destroyed in preference to their semiconducting counterparts when the wavelength and power intensity of the irradiation are appropriate and the carbon nanotubes are not heavily bundled. Our method takes advantage of these two species' different rates of photolysis-assisted oxidation, creating the possibility of defining the semiconducting portions of carbon nanotube (CNT) networks using optical lithography, particularly when constructing all-CNT FETs (without metal electrodes) in the future. 相似文献
940.
Yanagimoto Y Negishi Y Fujihara H Tsukuda T 《The journal of physical chemistry. B》2006,110(24):11611-11614
Undecagold cluster compounds [Au11(BINAP)4X2]+ (X = Cl and Br) were synthesized by chemical reduction of the corresponding precursor complexes, Au2X2(BINAP), where BINAP represents the bidentate phosphine ligand 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl. The circular dichroism spectra of Au11 stabilized by the enantiomers [Au11(R-BINAP)4X2]+ and [Au11(S-BINAP)4X2]+ exhibited intense and mirror-image Cotton effect, whereas those of Au11(3+) clusters stabilized by achiral monodentate phosphine ligands did not. The origin of the chiroptical activity of [Au11(BINAP)4X2]+ is discussed in the context of the structural deformation of the Au11(3+) core. 相似文献