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931.
Recent progress in the synthesis of nanostructured silica-based materials through the self-assembly process using well-designed
alkoxysilane precursors is presented. Alkoxysilanes with covalently attached hydrophobic organic tails become amphiphilic
when hydrolyzed to form silanol groups, leading to the formation of various mesostructures upon evaporation of solvents. The
precursors having large oligosiloxane heads are particularly important because of their ability to form cylindrical assemblies,
providing a direct pathway to ordered porous silica by removal of the organic groups. Our recent research includes (i) templated-synthesis
of hierarchically ordered structures and (ii) design of molecules having chemically cleavable bonds to generate pores without
calcination. 相似文献
932.
Doi Y Ikeda A Akiyama M Nagano M Shigematsu T Ogawa T Takeya T Nagasaki T 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(29):8892-8897
Water-soluble fullerenes have attracted attention as promising compounds that have been used to forge new paths in the field of photo-biochemistry. To prepare water-soluble fullerenes, we employed lipid-membrane-incorporated fullerenes (LMICx; x=60 or 70) by using the fullerene exchange method from a gamma-cyclodextrin (gamma-CD) cavity to vesicles. LMIC60 have low toxicity in the dark and engender cell death by photoirradiation (lambda>350 nm). Furthermore, the photodynamic activity of LMIC70 is 4.7-fold that of LMIC60 for the same photon flux (lambda>400 nm). One of the reasons for the higher phototoxicity of LMIC70 is the higher generation of singlet oxygen (1O2) in LMIC70 than in LMIC60. The difference between LMIC60 and LMIC70 is considered to be simply derived from the amount of light absorption in the 400-700 nm region that is suitable for photodynamic therapy (PDT). To the best of our knowledge, this is the first case in which biological activity of C70 and its derivatives toward HeLa cells has been assayed. 相似文献
933.
Taisuke Nakanaga Hidekazu Nagai Atsushi Suzuki Yukio Fujiwara Hidehiko Nonaka 《Journal of photochemistry and photobiology. A, Chemistry》2008,197(2-3):266-272
Multiphoton ionization and the subsequent dissociation process of metal cluster complexes Os3(CO)12 and Ir4(CO)12, prepared in a supersonic jet, were studied by means of multiphoton ionization with time-of-flight (TOF) mass detection. The ionization energies of Os3(CO)12 and Ir4(CO)12 were determined to be 7.95 and 8.3 eV, respectively, from the laser wavelength at the ionization threshold. The coordination energies of Os3(CO)12+ and Ir4(CO)12+ ions were also determined to be 1.6 and 1.2 eV, respectively, from the excitation energy needed to cause the appearance of fragment ions. The observed values agreed reasonably well with the ones calculated by using the density functional theory method. 相似文献
934.
Meier DM Urakawa A Turrà N Rüegger H Baiker A 《The journal of physical chemistry. A》2008,112(27):6150-6158
Molecular interactions between cinchonidine (CD) and 2-methyl-2-hexenoic acid (MHA) have been studied by means of NMR, ATR-IR MES, DFT, and ab initio molecular dynamics. These interactions are of particular interest due to their pivotal role in the chiral induction occurring in the heterogeneous catalytic asymmetric hydrogenation of alpha,beta-unsaturated acids. The population density of the Open(3) conformer of CD, the most populated one at room temperature in apolar solvents, considerably increased to a maximum by addition of MHA to CD in toluene. The CD-MHA complex showed prominent symmetric and asymmetric carboxylate stretching vibrations in the regions of 1350-1410 and 1520-1580 cm(-1), respectively. DFT calculations revealed that these vibrational frequencies are expected to significantly shift depending on the chemical surrounding of MHA, that is, the hydrogen bond network. Earlier postulated 1:1 binding between CD and MHA was considered unlikely; instead, a dynamic equilibrium involving the MHA monomer and dimer, the 1:3 and possibly 1:2 CD-MHA complexes, were rationalized. Stable CD-MHA structures suggested by DFT calculations are the "1:3, halfN, cyclic" and the "1:3, halfN, cyclic tilted" complexes, where three MHA molecules are connected in wire by hydrogen bonding, two having direct interaction with CD. The confinement of CD's torsional motions in the complexes, leading to a slightly distorted Open(3) conformer via specific hydrogen-bonding interactions, was clearly reproduced by ab initio molecular dynamics, and the stable and flexible nature of the interaction was verified. Theoretical IR spectra of the complexes reproduced the characteristic vibrational frequencies of the complexes observed experimentally, supporting the stability of the 1:3 and implying the possibility of even higher molecular weight CD-MHA complexes. 相似文献
935.
Nobusawa K Ikeda A Tanaka Y Hashizume M Kikuchi J Shirakawa M Kitahara T Fujita N Shinkai S 《Chemical communications (Cambridge, England)》2008,(15):1801-1803
We solubilised SWNTs of short length using a mechanochemical high-speed vibration milling (HSVM) through formation of complexes between the SWNTs and chelate complexes; the mixture formed a network structure on mica. 相似文献
936.
Makarova EA Shimizu S Matsuda A Luk'yanets EA Kobayashi N 《Chemical communications (Cambridge, England)》2008,(18):2109-2111
meso-Aryl tribenzosubporphyrin was synthesized by a self-condensation of 3-benzalphthalimidine and by a condensation of phthalimide with phenylacetic acid using boric acid as a template; the compounds derived were characterized based on a wide range of spectroscopic and electrochemical methods. 相似文献
937.
938.
Atsushi Atsuji 《Potential Analysis》2008,29(2):119-138
We show a second main theorem of Nevalinna theory for meromorphic functions on complex submanifolds in C
n
. This has a similar form to the classical one and has a remainder term including Ricci curvature. We also give a concrete
computation of the remainder term in the case of nonsingular algebraic submanifolds.
Partially supported by the Grant-in-Aid for Scientific Research (C), Japan Society for the Promotion of Science. 相似文献
939.
940.