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991.
Akiyama M Ikeda A Shintani T Doi Y Kikuchi J Ogawa T Yogo K Takeya T Yamamoto N 《Organic & biomolecular chemistry》2008,6(6):1015-1019
Unmodified [60]fullerenes (C60) were solubilised with high stability using various type of poly(ethylene glycol) (PEG) based block copolymer micelles. Block copolymer micelle-incorporated C60 fullerenes were studied in cultures for biological activities using human cervical cancer HeLa cells. As a result, the cationic block copolymer micelles delivered C60 into the cells depending on their surface densities and showed cytotoxicity under photoirradiation. 相似文献
992.
Manzacidins, a family of bromopyrrole alkaloids, have attracted much attention from the synthetic community due to their intriguing structures, bearing chiral tertiary and secondary stereocentres in a 1,3-relationship, and biological activities. In this article, we summarise the approaches for the preparation of manzacidins using novel synthetic methodologies. Organocatalysis and Lewis acid catalysis, as well as transition-metal catalysis, offered efficient ways to access these molecules. 相似文献
993.
We herein report a new synthetic method for the preparation of α-hydroxyketones by the dioxygenation of alkynes. The reaction proceeds at room temperature under the action of Fe porphyrin and pinacolborane under air as a green oxidant to produce α-hydroxyketones. The mild reaction conditions allow chemoselective oxidation with functional group tolerance. Terminal alkynes in addition to internal alkynes are applicable, affording unsymmetrical α-hydroxyketones that are difficult to obtain by any reported dioxygenation of unsaturated C−C bonds. 相似文献
994.
Fujioka H Okitsu T Ohnaka T Li R Kubo O Okamoto K Sawama Y Kita Y 《The Journal of organic chemistry》2007,72(21):7898-7902
A mild and efficient method for the preparation of O,O-mixed, O,S- and N,O-acetals from symmetrical O,O-acetals has been developed. Thus, the treatment of symmetrical O,O-acetals with TESOTf and 2,4,6-collidine formed weakly electrophilic collidinium salts. The addition of nucleophiles, such as an alcohol, lithium thioxide, and sodium azide, to the salts afforded the corresponding O,O-mixed, O,S- and N,O-acetals in good yields. The reaction proceeded under weakly basic conditions. No overreaction then occurred and many acid-labile functional groups could remain intact. 相似文献
995.
Nanometer-size metal coordination polymers are fascinating to explore, since their unique properties are controlled by a large ratio of surface atoms, which is an entirely different effect from that in a bulk crystal. In this report, we have demonstrated the reaction time-induced structural conversion of nanometer-sized metal coordination nano-polymers (MCNPs). The MCNP selected here was a Prussian blue analogue, cobalt hexacyanoferrate (Fe-CN-Co) with ca. 3 nm. When Fe-CN-Co MCNPs were synthesized in reverse micelles of cationic surfactants, cetyltrimethylammonium halides [CTAX, X=B (bromide), C (chloride)], their color dramatically changed from red to green with increasing the reaction time. We investigated the mechanism of this characteristic color change using XRD, FT-IR, UV-vis spectra, CHN elemental analyses, ICP, and TGA, which indicated that the coordination geometry of Co(II) ions was changed from a 6-coordinate octahedral (Oh) to a 4-coordinate tetrahedral (Td) with clear crystal distortion. The magnetic behavior of the prepared Fe-CN-Co MCNPs was also reaction-time dependent, as illustrated by SQUID and 57Fe M?ssbauer spectra. 相似文献
996.
Yamashita S Shiga T Kurashina M Nihei M Nojiri H Sawa H Kakiuchi T Oshio H 《Inorganic chemistry》2007,46(10):3810-3812
Reactions of quinquedentate Schiff base ligands with Mn and Cu ions afforded icosa- and hexadecanuclear mixed-metal clusters in which dinuclear CuII complexes trapped oxo-bridged [MnIII8MnIV4O12] and [MnIII6O6] cores, respectively. Maximum entropy method analysis for synchrotron X-ray diffraction data was used to determine the oxidation states of the Mn ions. 相似文献
997.
Ikeda A Doi Y Nishiguchi K Kitamura K Hashizume M Kikuchi J Yogo K Ogawa T Takeya T 《Organic & biomolecular chemistry》2007,5(8):1158-1160
Intracellular uptake of a lipid-membrane-incorporated C(60) with a cationic surface into HeLa cells was found to induce cell death under visible light irradiation in high efficiency. 相似文献
998.
Highly stereoselective 1,3-dipolar cycloadditions of methacrolein and nitrones could be realized by the use of bis-titanium chiral Lewis acid catalyst. Key to the success is the introduction of bulky N-substituent on nitrone to attenuate the undesired Lewis acid-nitrone complexation. 相似文献
999.
In this issue of Chemistry & Biology, Kelly and colleagues describe the development of two novel ROS-generating compounds [1] that specifically localize in the nucleus or mitochondrion. Their application reveals that nuclei and mitochondria respond differently to oxidative stress, in terms of gene expression and survival pathway activation. 相似文献
1000.
Electronic absorption spectra and Raman spectra of N,N-dimethyl-p-nitroaniline (DMPNA) have been measured in various fluids from the gaseous-like conditions in supercritical fluids (SCFs) to highly polar room-temperature ionic liquids (RTILs). We found that the S0-S1 absorption band center of DMPNA in RTILs is mostly determined by the molar concentrations of ions. On the other hand, the bandwidth of the absorption spectrum does not follow the expectation from a simple dielectric continuum model. Especially in SCFs, the bandwidth of the absorption spectrum decreases with increasing solvent density, suggesting that the intramolecular reorganization energy is a decreasing function of the solvent density. The Raman shift of the NO2 stretching mode has been proven to be a good indicator of the solvent polarity; i.e., the vibrational frequency of the NO2 stretching mode changes from 1340 cm-1 in mostly nonpolar solvent such as ethane to 1300 cm-1 in water. The linear relationship between the absorption band center and the vibrational frequency of the NO2 mode, which was observed for conventional liquids in a previous paper (Fujisawa, T.; Terazima, M.; Kimura, Y. J. Chem. Phys. 2006, 124, 184503), holds almost well for all fluids including SCFs and RTILs. On the other hand, the vibrational bandwidth does not show a simple relationship with the absorption band center. The vibrational bandwidths in RTILs are generally larger in comparison with those in conventional liquids with similar polarity scales. Among the RTILs we investigated, the vibrational bandwidth loosely correlates with the molecular size of the anion. A similar dependence on the anion size is also observed for the bandwidth of the absorption spectrum. We have also investigated the excitation wavelength dependence of the Raman shift of the NO2 stretching mode in RTILs. The extent of the dependence on the excitation wavelength in all fluids is well correlated with the vibrational bandwidth. 相似文献