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41.
The synthesis and properties of novel anthracene-bridged porphyrin dimers having an oxomolybdenum(V) porphyrin unit, H(2)(DPA)[Mo(V)O(OMe)] (1) and (DPA)[Mo(V)O(OMe)][Zn(II)(MeOH)] (2), and the relevant monomer porphyrin complexes Mo(V)O(MPP)OMe (3) and Zn(II)(MPP) (4) are presented. An oxomolybdenum(V) unit was introduced into one of the two porphyrins in DPA to give 1, which has a free-base porphyrin unit. By introducing a zinc(II) ion to the free-base part, a mixed-metal complex of 2 was prepared and isolated. The structure of 2 was analyzed by X-ray crystallography (2.(7)/(6)CH(2)Cl(2), triclinic, P(-)1 (no. 2), a = 15.2854(12) A, b = 19.9640(15) A, c = 13.6915(12) A, alpha = 90.968(3), beta = 113.108(4), gamma = 96.501(4), Z = 2, R1 = 9.9, wR2 = 19.2). The structure of 2 demonstrated that a methanol is stably coordinated to the Zn(II) ion with the aid of a hydrogen bond to the methoxo ligand on the Mo(V) ion in the binding pocket of DPA. The electrochemical measurements of 2 suggested that the methanol was kept in the pocket of DPA in solution even at the reduced state of the molybdenum ion. 相似文献
42.
Arakawa M Hasegawa K Funatsu K 《Journal of chemical information and computer sciences》2003,43(5):1390-1395
Molecular alignment is an important step in three-dimensional quantitative structure-activity relationship (3D-QSAR) such as comparative molecular field analysis (CoMFA). A reasonable molecular alignment is necessary for building a 3D-QSAR model. In this paper, a novel method for molecular alignment using the Hopfield Neural Network (HNN) is introduced. Four kinds of chemical properties are assigned to each atom of a molecule. Then, those properties between two molecules correspond to each other using HNN. To validate our method, HNN was applied to 12 pairs of enzyme inhibitors cited from the Protein Data Bank (PDB). As a result, our method could successfully reproduce the real molecular alignments obtained from X-ray crystallography. 相似文献
43.
A simple, accurate and reproducible reversed-phase high-performance liquid chromatography (HPLC) method was developed for the separation and characterisation of alkylphenols (APs) and alkylphenol polyethoxylates (APEOs), using a C18 octadecyl silica (ODS) column. APs and each APEO oligomer were separated successfully within a reasonable time without gradient elution. An excellent resolution was obtained, even for mixtures of APs and low EO number APEOs, which are otherwise difficult to separate using conventional normal-phase HPLC methods. This method, combined with solid-phase extraction, was highly applicable for the simultaneous determination of alkylphenols and alkylphenol ethoxylates in real samples. 相似文献
44.
Hiroyuki Ishibashi Motofumi Okada Atsuko Akiyama Kazuyuki Nomura Masazumi Ikeda 《Journal of heterocyclic chemistry》1986,23(4):1163-1166
2,3-Dihydro-5H-1,4-benzoxathiepins were prepared by intramolecular Friedel-Crafts reactions of ethyl α-[2-(aryloxy)ethylthio]-α-chloroacetates or by acid-catalyzed cyclizations of ethyl α-[2-(aryloxy)ethylsulfinyl]-acetate. 1,2,3,5-Tetrahydro-4,1-benzothiazepines were similarly prepared. 相似文献
45.
Highly Selective Separation of Rhodopsin from Bovine Rod Outer Segment Membranes Using Combination of Divalent Cation and Alkyl(thio)glucoside 总被引:1,自引:0,他引:1
The micellization process of bovine rod outer segment (ROS) membranes is investigated utilizing a series of neutral detergents. It is found that when alkyl(thio)glucosides with an appropriate hydrophilic–lipophilic balance (e.g. octylthioglucoside) are used in combination with a divalent cation, rhodopsin is selectively extracted from ROS membranes at a specific detergent-to-membrane ratio. This allows remarkable purification of rhodopsin by a single-step solubilization, because the residual membranes are heavily aggregated in the presence of divalent cation and are therefore easily sedimented by low-speed centrifugation. The absorption spectrum of the supernatant reproducibly exhibits an A280 /A500 value of 1.6, an excellent value that could rarely be obtained by chromatographic purification. The degree of purification also depends on the type of divalent cation included in the solubilization solution; specific binding of IIB-series cations (Zn2+ and Cd2+ ) to ROS membranes is suggested to play an important role in the solubilization process. The present result represents a unique example of selective solubilization of a specific membrane protein from highly aggregated membranes. 相似文献
46.
Kakiuchi K Okada H Kanehisa N Kai Y Kurosawa H 《The Journal of organic chemistry》1996,61(9):2972-2979
Acid-catalyzed rearrangement of 5-cyclopentylidenecyclooctanone derivatives 9a-c was examined to obtain polyspiropolyquinanes 11a-c, considered to have a unique helical structure, through cascade rearrangement pathways consisting of continuous transannular cyclization followed by successive 1,2-alkyl shifts. The substrates were prepared easily by use of the Wittig or McMurry reaction. Reaction of the 5-cyclopentylidenecyclooctanone (9a) with acid gave the expected dispirotriquinane ketone 11a in high yield. The precise mechanism was elucidated by a deuterium-labeling experiment. In the case of the ketone 9b, having another spiroannulated cyclopentane ring attached on 9a, the trispirotetraquiane 11b was not obtained but the bis-propellane-type tetrahydrofuran 25 was produced exclusively. The 5-(5'-cyclopentylidenecyclooctylidene)cyclooctanone (9c) afforded the polycyclic compounds 27-31, depending on the acid used, instead of the desired tetraspiropentaquinane 11c. The structures of the products were determined by NMR spectral data including 2D (13)C INADEQUATE spectra and X-ray crystallographic analyses. The unexpected rearrangement pathways are also discussed. 相似文献
47.
Masakazu Uramoto Kimie Kobinata Kiyoshi Isono Tsutomu Higashijima Tatsuo Miyazawa Ellen E. Jenkins James A. McCloskey 《Tetrahedron》1982,38(11):1599-1608
New chitin synthetase inhibitors, neopolyoxins A, B, and C were isolated from the culture filtrate of Streptomyces cacaoi subsp. asoensis. Their absolute structures have been established on the basis of chemical and spectroscopic evidence. They are structural analogs of the polyoxins. As a nucleobase, neopolyoxin C possesses uracil, while neopolyoxins A and B contain the imidazoline moiety. A ring contraction reaction of pyrimidine nucleoside into imidazoline nucleoside played a key role in the structure determination of the nucleoside moiety. A similar transformation was suggested for the biosynthesis of neopolyoxins A and B. 相似文献
48.
W. K. A. Kumuduni Y. Nakata T. Okada M. Maeda 《Applied physics. B, Lasers and optics》1994,58(4):289-294
One-dimensional imaging laser-induced fluorescence spectroscopy has been used for in-situ measurements of spatial distributions of YO molecules produced during the ArF-laser ablation of YBa2 Cu3 O
7–x
in vacuum and oxygen gas environment. The time-integrated angular distribution of particles ejected in vacuum has a cos
n
form, where 11 <n < 13. When oxygen gas was introduced, YO molecules were confined in a smaller volume, and temporal changes of their spatial distribution were interpreted in terms of blast-wave formation. 相似文献
49.
50.