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991.
Koichi Tanaka Hideyuki Takano Zofia Urbanczyk-lipkowska 《Journal of inclusion phenomena and macrocyclic chemistry》2006,56(3-4):281-285
The host compounds 1,1’-binaphthyl-2,2′-dihydroxy-5,5′-dicarboxylic acid (1) and 1,1′-binaphthyl-2,2′-dihydroxy-6,6′-dicarboxylic acid (2) have been synthesized, and their inclusion properties have been studied. Inclusion complexes formed by 1 and 2 with volatile guests such as acetone and methanol release the guests only at much higher temperatures than their boiling
points. The crystal structures of the inclusion complexes have been determined from single crystal X-ray diffraction data
and show different host lattices. 相似文献
992.
Łada T. Przybylski K. Morawski A. Prażuch J. Brylewski T. 《Journal of Thermal Analysis and Calorimetry》2001,64(2):611-615
The fabrication method of superconducting thin films of compositions HgBa2Ca2Cu3O8+δ (Hg-1223) and Tl2Ba2CuOy (2201) on single-crystalline SrTiO3 and LaAlO3 substrates is reported. The highest obtained T
c was 134 K and J
c over 106 A cm–2 at 77 K. High pressure DTA(HP-DTA) was applied to grow mercury- and thallium-based high-temperature superconducting crystals
and thin films, to identify melting points of particular phases within these oxide systems and determine suitable processing
conditions. The DTA system operates at the: maximum temperature of 1200°C, volume up to 5 cm3, working pressure up to 1.5 GPa and at a working atmosphere — inert gas with up to 25% oxygen.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
993.
Kasani Aparna Professor Setharampattu S. Krishnamurthy Munirathinam Nethaji 《无机化学与普通化学杂志》1995,621(11):1913-1921
Lanthanide nitrate complexes of diphosphazane dioxides Ph2P(O)N(Pri)P(O)Ph2 ( 1 ) and (PhO)2P(O)N(Me)P(O)(OPh)2 ( 2 ) have been synthesised and studied by conductometry, IR, multinuclear NMR spectroscopic methods and X-ray diffraction. Ligand 2 is accessible by two different methods, viz., by direct oxidation of the phosp(III)azane ligand or by starting from phosph(V)azane chloro precursor. The structure of 2 is confirmed by X-ray diffraction. Crystallographic data for 2 : Triclinic, Space group P1 , a = 10.078(1), b = 10.575(3), c = 12.364(4) Å, α = 75.70(2)°, α = 75.56(1)°, γ = 77.68(1)°, Z = 2, V = 1 220 Å3; structure refined to RF = 0.0459 on 3 495 data with F > 3σ(F). The diphosphazane dioxide ligand exhibits trans geometry in the solid state. The structure of a lanthanide complex, [Pr(NO3)3( 2 )2] ( 14 ) is also determined by X-ray diffraction. Crystallographic data for 14 : Trigonal, Space group P32, a = b = 15.710(2), c = 40.067(2) Å, Z = 6, V = 8 564 Å3; structure refined to RF = 0.0430 on 8 077 data with F > 5σ(F). The two diphosphazane dioxide ligands and the nitrate groups are coordinated to praseodymium in a bidentate chelate fashion. The geometry around the ten coordinated metal is distorted bicapped square antiprism. 相似文献
994.
UV absorption spectra of acetyl fluoride-h3 and -d3 (CH3COF and CD3COF) molecules in the region of S1S0 electronic transitions are investigated. The origins (00
0 or 140±
0) of these transitions are observed at 39912 and 39904 cm–1, respectively, and some of the fundamental frequencies of these molecules in the s0 and S1 states are determined. In particular, the systems of torsion and inversion (out-of-plane C=O vibrations) energy levels are studied. The geometric parameters of an acetyl fluoride-h3 molecule in the S1 state are estimated by the theoretical simulation of the rotational contours of the 00
0 (140±
0) band. These data are used to evaluate the potential barriers to internal rotation in the S0 and S1 states, which were found to be 360 and 560 cm–1 for acetyl fluoride-h3 and 380 and 770 cm–1 for acetyl fluoride-d3, respectively, as well as the potential barriers to inversion in the S1 states, which were found to be 2090 and 2370 cm–1 for acetyl fluoride-h3 and acetyl fluoride-d3, respectively.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1957–1964, November, 1994.In conclusion, the authors would like to acknowledge T. S. Kuznetsova for the synthesis and purification of the AF samples.The research presented here was supported in part by the International Science Foundation under grant No. MJ 1000. 相似文献
995.
Protein fold recognition 总被引:4,自引:0,他引:4
Summary An important, yet seemingly unattainable, goal in structural molecular biology is to be able to predict the native three-dimensional
structure of a protein entirely from its amino acid sequence. Prediction methods based on rigorous energy calculations have
not yet been successful, and best results have been obtained from homology modelling and statistical secondary structure prediction.
Homology modelling is limited to cases where significant sequence similarity is shared between a protein of known structure
and the unknown. Secondary structure prediction methods are not only unreliable, but also do not offer any obvious route to
the full tertiary structure. Recently, methods have been developed whereby entire protein folds are recognized from sequence,
even where little or no sequence similarity is shared between the proteins under consideration. In this paper we review the
current methods, including our own, and in particular offer a historical background to their development. In addition, we
also discuss the future of these methods and outline the developments under investigation in our laboratory. 相似文献
996.
Hamada Fumio Kondo Yoshihiko Ito Riko Suzuki Iwao Osa Tetsuo Ueno Akihiko 《Journal of inclusion phenomena and macrocyclic chemistry》1993,16(3):273-281
The crystal structure of thiamine iodide sesquihydrate has been determined by X-ray diffraction methods as a host-guest model for coenzyme-substrate interactions. The asymmetric unit contains two chemical units. Both the thiamine molecules A and B, which are crystallographically independent, assume the usualF conformation and have a disordered hydroxyethyl side chain. An iodide anion (or a water molecule) bridges the pyrimidine and thiazolium rings of molecule A (or B) by forming a hydrogen bond with the amino group and an electrostatic contact with the thiazolium ring to stabilize the molecular conformation. In the crystal the thiamine molecules self-associate to form a pipe-like polymeric structure, in which four thiamine hosts surround an iodide guest and hold it through C(2)-H...I hydrogen bonds and thiazolium...I electrostatic interactions. Crystal data: C12H17N4OS+·I– · 1.5 H2O, monoclinic,P21/c, a=12.585(2), b=25.303(5), c=12.030(2) Å, =115.15(1)°,V=3468(1) Å3,Z=8,D
c=1.606 g cm–3,R=0.045 for 3328 observed reflections.
Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP. 82156 (13 pages). 相似文献
997.
Koichiro Fukuda Miyuki Hisamura Nobuyuki Tera 《Journal of solid state chemistry》2007,180(6):1809-1815
A new quaternary layered carbide, Zr2[Al3.56Si0.44]C5, has been synthesized and characterized by X-ray powder diffraction, transmission electron microscopy and thermopower and electrical conductivity measurements. The crystal structure was successfully determined using direct methods, and further refined by the Rietveld method. The crystal is trigonal (space group R3m, Z=3) with lattice dimensions of a=0.331059(5), c=4.09450(5) nm and V=0.38864(1) nm3. The final reliability indices calculated from the Rietveld refinement were Rwp=6.24%, Rp=4.21% and RB=0.82%. The crystal structure is composed of electroconductive NaCl-type ZrC slabs separated by Al4C3-type [Al3.56Si0.44]C3 layers. This material had thermoelectric properties superior to those of the ternary layered carbides Zr2Al3C4 and Zr3Al3C5, with the power factor reaching 7.6×10−5W m−1 K−2. 相似文献
998.
999.
New polymeric adsorbents (ZH-02, ZH-03) containing benzoyl group for adsorbing and removing 4-methylaniline from its aqueous solutions were prepared. Studies on the isotherms and the comparison of desorption conditions evidenced through the adsorption of 4-methylaniline in water onto ZH-02 and ZH-03, namely that there are chemisorption‘s transitions at a proper higher temperature. Mini-colunm adsorption studies of 4-methylaniline on XAD-4, ZH-02 and ZH-03 at 288 K show that the breakthrough capacities are 2.39, 2.99 and 3.19 mmol/g and the total capacities are 3.45, 3.92 and 4.35 mmol/g, respectively. 相似文献
1000.
ZENG Xiang-Chao② XU Shi-Hai LIU Po-Runa DENG Qin-Ying 《结构化学》2005,24(3):299-302
1 INTRODUCTION Indole and its derivatives have attracted much at-tention due to their chemical properties as well asbiological activities[1, . They have been widely used 2]as the materials for producing pigment, perfume,plant growth regulators, etc. Recently, it has alsobeen found that some indole derivatives present anti-tumor and antiviral activities[3~5]. During our sear-ches for bioactive compounds, a series of indole deri-vatives were synthesized, among … 相似文献