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Tertiary structure changes in DNA duplexes, induced by Hoechst 33258 binding, have been examined by the use of atomic force microscopy. Besides minor groove binding, which is an established mode of binding for this drug, Hoechst 33258 has now been found to show another binding mode, which causes an unwinding of the duplex. When the drug concentration is as high as 0.5 microg/ml, the Hoechst 33258 molecule seems to function as a clamp for two DNA chains and forms a condensate. The condensate was found to have a toroidal shape. By surveying more than 100 microscopic images of such condensates formed in I microg/ml drug solution, a mechanism of toroidal condensate formation has been proposed. 相似文献
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The standardization of EDTA solution against metallic copper as primary standard is studied. Six indicators were examined; titration with PAN as indicator at pH 6 is recommended. 相似文献
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Hidetaka Yuge Toschitake Iwamoto 《Journal of inclusion phenomena and macrocyclic chemistry》1992,14(3-4):217-235
The crystal structures of the four title clathrate compounds Cd(NH3)2Cd(CN)4 · 2C6H6,I, Cd(NH3)2Cd(CN)4 · 2C6H5NH2,II, Cd(NH2CH2CH2NH2)Cd(CN)4 · 2 C6H5NH2,III, and Cd(C6H5NH2)2Cd(CN)4 · 0.5C6H5NH2,IV, have been analyzed by single crystal X-ray diffraction methods. CompoundI crystallizes in the monoclinic space groupC2/c,a = 12.063(2),b = 12.174(2),c = 14.621(1) Å,β = 90.976(9)°,Z = 4,R = 0.042 for 2388 reflections;II: monoclinic C2/c,a = 12.1951(9),b = 12.078(1),c = 14.6921(7) Å,β = 93.436(5)°,Z = 4,R = 0.039 for 2374 reflections;III: monoclinicCc,a = 11.027(1),b = 12.0767(9),c = 15.837(1) Å,β = 92.059(9)°,Z = 4,R = 0.041 for 2883 reflections; andIV: monoclinicP21/n,a = 15.169(2),b = 16.019(2),c = 8.866(1) Å,β = 95.73(1)°,Z = 4,R = 0.052 for 3612 reflections. The three-dimensionalcatena-[diamminecadmium(II) tetra-μ-cyanocadmate(II)] hosts ofI andII are substantially isostructural to that of the already known Hofmann-Td-type Cd(NH3)2Hg(CN)4 · 2C6H6. The three-dimensional en-Td-typecatena-[catena-μ-ethylenediaminecadmium(II) tetra-μ-cyanocadmate(II)] host ofIII, reinforced by the catena-μ-en linking between the octahedral Cd atoms, accommodates the aniline as the guest with a monoclinic distortion from the tetragonal symmetry of the previously reported en-Td-type benzene clathrate. InIV dual behavior of aniline, one as the unidentate ligand in the three-dimensional host and the other as the guest in the cage-like cavity, has been demonstrated. 相似文献
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Hidetaka Yuge Toschitake Iwamoto 《Journal of inclusion phenomena and macrocyclic chemistry》1996,26(1-3):119-126
The title inclusion compound [{NH2(CH2CH2)2NCH2CH2NH2}2H][Cu4(CN)7] was obtained as single crystals from an aqueous solution containing CuCN, KCN, andN-(2-aminoethyl)piperazine. It crystallizes in the monoclinic space groupP2/n,a = 12.3829(9),b = 8.5970(9),c = 12.6633(7) Å, = 109.984(5)°,z = 2,R = 0.035 for 2921 independent reflections. The inclusion structure is composed of the hydrogen-bonded dimeric onium guest [{NH2(CH2CH2)2NCH2CH2NH2}2H]3+ and the negatively-charged three-dimensional host [CU4(CN)7]3– in which the CN-bridged framework Cu(I) atoms are all tetrahedral. A polyacene-like one-dimensional array of hexagons cornered by Cu(I) atoms and edged by -CN- linkages is arrayed in parallel to theb axis and stacked approximately along the c axis. The Cu(I) corner shared in the one-dimensional array extends an N-coordinate CN group along the c axis to a pair of unshared Cu(I) corners for which the C end behaves as a bifurcated ligand to build up the three-dimensional host structure. The cavity is composed of two networks of the hexagons at the top and bottom and pillared by six >CN- groups and accommodates a dimeric guest ofN-(2-aminoethyl)piperazinium cations protonated at each 4-N with the cations being hydrogen-bonded to each other through the 2-NH2 groups sharing another H+.Presented at the Sixth International Seminar on Inclusion Compounds, Istanbul, Turkey, 27–31 August, 1995. 相似文献
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Tai Hasegawa Toschitake Iwamoto 《Journal of inclusion phenomena and macrocyclic chemistry》1988,6(2):143-156
The crystal structures of the four title compounds have been analyzed by single crystal X-ray diffraction methods at room temperature. Three with a general formula Cd[NH2(CH2)6NH2]Ni(CN)4·G (G=m-toluidine,Im;p-toluidine,Ip; and 2,4-xylidine,Ix) are the inclusion compounds of the respective aromatic molecules in the three-dimensional metal complex host (1,6-diaminohexane)cadmium(II) tetracyanonickelate(II). The remaining one is a coordination complex ofp-toluidine, bis(p-toluidine) (1,6-diaminohexane)cadmium(II) tetracyanonick-elate(II),II, Im, Ix, andII crystallize under similar experimental conditions;Ip is obtained using thep-toluidinemesitylene mixture at higher dilution than that used forII. Im crystallizes in the tri linic space group \(P\bar 1\) , witha=9.725(2),b=7.598(1),c=7.177(1) Å, α=90.44(1), β=98.80(1), γ=95.70(1)o, andZ=1 (the final conventionalR=0.037 for 3526 reflections);Ip: monoclinic,P2/m,a=9.540(2),b=7.611(1),c=7.120(1) Å, β=100.95(1)o, andZ=1 (R=0.027 for 1700 reflections);Ix: monoclinic,P2/m,a=9.628(2),b=7.613(1),c=7.122(1) Å, β=100.01(1)o, andZ=1 (R=0.049 for 2704 reflections);II: monoclinic,P21/n,a=12.107(3),b=10.117(2),c=12.471(3) Å, β=113.67(2)o, andZ=2 (R=0.037 for 2616 reflections). The structures ofIm, Ip andIx are similar to that of theo-toluidine inclusion compound of the same metal complex host. InII atrans pair of thep-toluidine molecules to the cadmium atom in the two-dimensional network formed by thecatena-μ-linkages of ?Cd?NH2(CH2)6NH2?Cd? and ?NC?Ni?CN?Cd?NC?Ni?CN?intersecting at each Cd atom; two cyanide groups of the tetracyanonickelate(II) moiety have free N-ends. 相似文献
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Masato Hashimoto Takafumi Kitazawa Tai Hasegawa Toschitake Iwamoto 《Journal of inclusion phenomena and macrocyclic chemistry》1991,11(2):153-158
The Hofmann-danon-typeo-xylene clathrate Cd[NH2(CH2)9NH2]Ni(CN)4·0.5(CH3)2C6H4, crystallizes in the triclinic space groupP witha = 15.118(3),b = 14.048(4),c = 7.325(1) Å, = 91.50(2), = 131.66(3), and = 107.50(2)°,V = 1051(1) Å3 andZ = 2. The structure, refined toR = 0.047 using 2851 reflections, reveals a three-dimensional host framework built of the layers of a two-dimensionalcatena-[cadmium tetra--cyanonickelate(Il)] network and of the ambidentate 1,9-diaminononane (danon) bridging the Cd atoms in adjacent networks. The guesto-xylene molecule is accommodated in the cavity formed in the interlayer space similar to that in the Hofmann-daotn-type. The skeleton of the danon in the Cd-NC9N-Cd linkage takes a (gauche)2(trans)8 conformation twisted at the (gauche)2 part in contrast with the all-trans conformation of 1,8-diaminononane in the Hofmann-daotn-type clathrate. The twisted (gauche)2 part of the danon skeleton occupies the interlayer space to such an extent that void space available for the guest o-xylene molecule decreases to half that in the Hofmann-daotn-type clathrate Cd[NH2(CH2)8NH2]Ni(CN)4·G.The Crystal structures of ,-Diaminoalkanecadmium(II)Tetracyanonickelate(II) - Aromatic Molecule Inclusion Compounds. VI. 相似文献
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Shin-ichi Nishikiori Toschitake Iwamoto 《Journal of inclusion phenomena and macrocyclic chemistry》1984,2(1-2):341-349
The title compound crystallizes in monoclinic space group P21/m with a=9.795(2), b=15.010(2), c=7.125(1) Å, =105.56(1)o, and Z=2. The structure has been refined to the weighted Rw=0.042 for 2742 reflections collected by counter method. Two-dimensionally extended but wavy cyanometal complex layers are bridged by 1,4-diaminobutane (dabn) to give a three-dimensional host structure which provides a channel-like cavity with the guest 2,5-xylidine molecule. The skeleton of the bridging dabn takes a trans-cis conformation to make the packing efficient between the cavity and the guest molecule. The series of Hofmann-dabn-type Cd(NH2 (CH2)4NH2) Ni (CN)4. nG inclusion compounds are described for several aromatic guest molecules G with various stoichiometric coefficients n.
Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82020 (22 pages). 相似文献
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Shinachi Nishikiori Yuhko Takahashi-Ebisudani Toschitake Iwamoto 《Journal of inclusion phenomena and macrocyclic chemistry》1990,9(2):101-112
The clathrate compounds of the title three-dimensional metal complex hosts have been prepared with various aliphatic, alicyclic, and aromatic guest molecules. The typical structure has been demonstrated for a cyclohexane clathrate (N-methyl-1,3-diaminopropane)cadmium(II) tetracyanonickelate(II)-cyclohexane(2/1) by X-ray single crystal analysis. The powder X-ray diffraction data were assigned for the other clathrates to the tetragonal systems isostructural to the cyclohexane clathrate in which the box-like cavity with the approximate dimensions of 7 × 7 × 5 Å3 accommodates the guest molecule. 相似文献
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Janusz Lipkowski Toschitake Iwamoto 《Journal of inclusion phenomena and macrocyclic chemistry》1987,5(4):545-549
A system of BASIC programs for a personal computer allowing the display of plane sections through crystal structures has been developed in order to analyse intermolecular contacts as well as the shape and size of intra- or intermolecular voids in the structure of inclusion compounds. The data consisting of lattice parameters, type of Bravais lattice, symmetry operations, and positional parameters of atoms in an asymmetric unit are stored in a data file, reusable and correctable. The structure is considered as an assembly of spherical atoms of given van der Waals radii. The section plane may be defined by either coordinates of three points or the crystallographic index. A series of sections parallel to the original one at a specified interval of distance may be calculated and displayed automatically, and memorized for further reviewing, modifying graphic features, etc. Hard copies may be prepared using a dot-matrix printer or plotting devices. The program may be applicable to any crystal structure with an arbitrary choice of atomic radii.Presented at the Fourth International Symposium on Inclusion Phenomena and the Third International Symposium on Cyclodextrins, Lancaster, U.K., 20–25 July 1986. 相似文献