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991.
Kazuhiro Hayasaka Toshikazu Ohtsuka Haruhisa Shirahama Takeshi Matsumoto 《Tetrahedron letters》1985,26(7):873-876
Africanol, which had been previously derived from humulene, was converted to dactylol through a formal 1,2-shift of a methyl group, which involved a cyclopropane sliding reaction and subsequent cyclopropane ring opening. 相似文献
992.
The temperature effects on the quantum yields φTS of the inverse (Tn → S1 intersystem crossings of anthracene, 9-methylanthracene and acridine are studied by the stepwise two-photon excitation technique. ΦTS of anthracene in ethanol increases with increasing temperature, while that of 9-methylanthracene does not depend on temperature, ΦTS of acridine in alkaline water decreases with increasing temperature. 相似文献
993.
Kaneto Uekama Yasuhide Horiuchi Masahiko Kikuchi Fumitoshi Hirayama Takanori Ijitsu Masao Ueno 《Journal of inclusion phenomena and macrocyclic chemistry》1988,6(2):167-174
Inclusion complexation of heptakis (2,6-di-O-methyl)--cyclodextrin (DM--CyD) with -tocopheryl acetate and -tocopheryl nicotinate in aqueous solution was studied by the solubility method. The aqueous solubilities of the esters were about 105 times increased by DM--CyD complexation. The phase-solubility diagram of the tocopheryl ester-DM--CyD systems showed a typicalA
p type, and the stability constants (K) of high-order complexes were estimated by analyzing the upward curvature of the diagrams. The solid complex of -tocopheryl nicotinate with DM--CyD in a molar ratio of 12 was prepared by the kneading method. The dissolution rate of the solid complex was much greater than that of the drug itself, and the rapidly dissolving form of -tocopheryl nicotinate, as an example, showed a markedly increased bioavailability (about 70-fold) after oral administration to fasted dogs. 相似文献
994.
Yanagi T Kikuchi K Takeuchi H Ishikaw T Nishimura T Kamijo T Yamamoto I 《Chemical & pharmaceutical bulletin》2001,49(3):340-344
We describe the practical synthetic route for (2S)-7-methoxy-1,2,3,4-tetrahydro-2-naphthylamine 1(2S)-2-amino-7-methoxytetraline; (S)-AMT]. (2R)-2-(3-Methoxybenzyl)succinic acid [(R)-1] was obtained by the optical resolution of 2-(3-methoxybenzyl)succinic acid (1) as the salt of (1R,2S)-2-(benzylamino)cyclohexylmethanol (7), and (R)-1 was converted to the optically active (2S)-7-methoxy-1,2,3,4-tetrahydro-2-naphthoic acid [(S)-2] by the intramolecular Friedel-Crafts reaction followed by catalytic hydrogenation. (S)-AMT was obtained from the acid (S)-2 by Hofmann rearrangement without racemization. 相似文献
995.
The nonlinear optical coefficientd
ij(kl) (2, 0,, ) for electric field-induced optical second harmonic generation in semiconductors is calculated by means of a perturbation treatment. The result is given directly as a Brillouin zone integral over a resonant energy denominator. A simplified energy band structure model is used to carry out the Brillouin zone integral. The analytic closed-form expression ford
ij(kl) (2, 0,, ) thus obtained permits the calculation of the absolute value of its spectrum from available energy band parameters. The dispersion ofd
11(11) (2, 0,, ) of Ge is numerically calculated, second harmonic photon energies being close to theE
0 andE
1 gaps. The results show pronounced resonant behaviours. 相似文献
996.
Yuya Domoto Masahiro Abe Kidai Yamamoto Takashi Kikuchi Makoto Fujita 《Chemical science》2020,11(38):10457
Discrete (M3L2)n cages assembled from a tripodal ligand (L) and metal ions (M: Cu(i) or Ag(i)) are embedded in networked coordination hosts formed by partial dissociation of the same discrete cages during the crystallization process. The resulting “eggs-in-an-egg-carton” structures provide unique examples of the co-crystallization of discrete and infinite coordination frameworks.Discrete coordination cages were connected into the infinite lattices via shape-complementary co-crystallization with networked coordination hosts in the “eggs-in-an-egg-carton” styles. 相似文献
997.
Shimada K Kato H Saito T Matsuyama S Kinugasa S 《The Journal of chemical physics》2005,122(24):244914
Uniform poly(ethylene glycol) (PEG) oligomers, with a degree of polymerization n=1-40, were separated by preparative supercritical fluid chromatography from commercial monodispersed samples. Diffusion coefficients, D, for separated uniform PEG oligomers were measured in dilute solutions of deuterium oxide (D(2)O) at 30 degrees C, using pulsed-field gradient nuclear magnetic resonance. The measured D for each molecular weight was extrapolated to infinite dilution. Diffusion coefficients obtained at infinite dilution follow the scaling behavior of Zimm-type diffusion, even in the lower molecular weight range. Molecular-dynamics simulations for PEG in H(2)O also showed this scaling behavior, and reproduced close hydrodynamic interactions between PEG and water. These findings suggest that diffusion of PEG in water is dominated by hydrodynamic interaction over a wide molecular weight range, including at low molecular weights around 1000. 相似文献
998.
Ariga K Nakanishi T Hill JP Shirai M Okuno M Abe T Kikuchi J 《Journal of the American Chemical Society》2005,127(34):12074-12080
Various amino acid-carrying amphiphiles were synthesized, and the pK values of the attached amino acid residues were investigated at the air-water interface and in aqueous vesicles using pi-A isotherm measurements, (1)H NMR titration, and IR spectroscopy in reflection-adsorption mode. The epsilon-amino group of the Lys residue embedded at the air-water interface displays a significant pK shift (4 or 5 unit) compared with that observed in bulk water, while the pK shift in aqueous vesicles was not prominent (ca. 1 unit). Moreover, pK values of the amino acids at the air-water interface can be tuned simply by control of the subphase ionic strength as well as by molecular design of the amphiphiles. A simple equation based on the dominant contribution by the electrostatic energy to the pK shift reproduces well the surface pressure difference between protonated and unprotonated species, suggesting a reduction in the apparent dielectric constant at the air-water interface. Hydrolysis of a p-nitrophenyl ester derivative was used as a model reaction to demonstrate the use of the Lys-functionalized monolayer. Efficient hydrolysis was observed, even at neutral pH, after tuning of pK for the Lys residue in the monolayer, which is a similar case to that occurring in biological catalysis. 相似文献
999.
The fluorescence from the lowest excited singlet state following excitation of the lowest triplet state was observed for anthracene, 9-methylanthracene, and 9-phenylanthracene in ethanol by a newly devised double excitation method which is essentially the combination of flash and laser photolysis. The quantum yield of intersystem crossing from the excited triplet state, Tn(n ? 2), to the lowest excited singlet state was markedly increased by methyl- and phenyl-substitution at the meso-position. 相似文献
1000.