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61.
Vaduganathan Yasodha Subbaiah Govindarajan John N. Low Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(5):m207-m215
The structures of five metal complexes containing the 4‐oxo‐4H‐pyran‐2,6‐dicarboxylate dianion illustrate the remarkable coordinating versatility of this ligand and the great structural diversity of its complexes. In tetraaquaberyllium 4‐oxo‐4H‐pyran‐2,6‐dicarboxylate, [Be(H2O)4](C7H2O6), (I), the ions are linked by eight independent O—H...O hydrogen bonds to form a three‐dimensional hydrogen‐bonded framework structure. Each of the ions in hydrazinium(2+) diaqua(4‐oxo‐4H‐pyran‐2,6‐dicarboxylato)calcate, (N2H6)[Ca(C7H2O6)2(H2O)2], (II), lies on a twofold rotation axis in the space group P2/c; the anions form hydrogen‐bonded sheets which are linked into a three‐dimensional framework by the cations. In bis(μ‐4‐oxo‐4H‐pyran‐2,6‐dicarboxylato)bis[tetraaquamanganese(II)] tetrahydrate, [Mn2(C7H2O6)2(H2O)8]·4H2O, (III), the metal ions and the organic ligands form a cyclic centrosymmetric Mn2(C7H2O6)2 unit, and these units are linked into a complex three‐dimensional framework structure containing 12 independent O—H...O hydrogen bonds. There are two independent CuII ions in tetraaqua(4‐oxo‐4H‐pyran‐2,6‐dicarboxylato)copper(II), [Cu(C7H2O6)(H2O)4], (IV), and both lie on centres of inversion in the space group P; the metal ions and the organic ligands form a one‐dimensional coordination polymer, and the polymer chains are linked into a three‐dimensional framework containing eight independent O—H...O hydrogen bonds. Diaqua(4‐oxo‐4H‐pyran‐2,6‐dicarboxylato)cadmium monohydrate, [Cd(C7H2O6)(H2O)2]·H2O, (V), forms a three‐dimensional coordination polymer in which the organic ligand is coordinated to four different Cd sites, and this polymer is interwoven with a complex three‐dimensional framework built from O—H...O hydrogen bonds. 相似文献
62.
Jaime Portilla Jairo Quiroga Justo Cobo John N. Low Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(6):o332-o333
In the title compound, C13H10O4, prepared by the condensation reaction between phthalic anhydride and pentane‐2,4‐dione, one of the acetyl groups in the pentane‐2,4‐dione fragment is almost coplanar with the isobenzofuran ring system, while the other group is twisted out of this plane by almost 80°. The corresponding C—C and C—O distances in the two acetyl units are consistent with dipolar delocalization into the coplanar unit only. There is no supramolecular aggregation of the molecules, but a number of rather short intermolecular contacts of C—H...O, O...O and O...C types occur. 相似文献
63.
Wilson Cunico Claudia R. B. Gomes Solange M. S. V. Wardell John N. Low Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(7):o411-o414
rac‐2‐Isopropyl‐3‐(2‐nitrobenzyl)‐1,3‐thiadiazolin‐4‐one, C13H16N2O3S, is a rare example of a racemate crystallizing in the space group P212121, with one molecule each of S and R configurations, whose conformations are almost mirror images, within the asymmetric unit. The molecules of S configuration are linked by two C—H...O hydrogen bonds into a three‐dimensional framework, and the molecules of R configuration are linked by two further C—H...O hydrogen bonds into a different type of three‐dimensional framework; the two frameworks are linked by a fifth C—H...O hydrogen bond. 相似文献
64.
Shaw R Laye RH Jones LF Low DM Talbot-Eeckelaers C Wei Q Milios CJ Teat S Helliwell M Raftery J Evangelisti M Affronte M Collison D Brechin EK McInnes EJ 《Inorganic chemistry》2007,46(12):4968-4978
We report the synthesis, by solvothermal methods, of the tetradecametallic cluster complexes [M14(L)6O6(OMe)18Cl6] (M=FeIII, CrIII) and [V14(L)6O6(OMe)18Cl6-xOx] (L=anion of 1,2,3-triazole or derivative). Crystal structure data are reported for the {M14} complexes [Fe14(C2H2N3)6O6(OMe)18Cl6], [Cr14(bta)6O6(OMe)18Cl6] (btaH=benzotriazole), [V14O6(Me2bta)6(OMe)18Cl6-xOx] [Me2btaH=5,6-Me2-benzotriazole; eight metal sites are VIII, the remainder are disordered between {VIII-Cl}2+ and {VIV=O}2+] and for the distorted [FeIII14O9(OH)(OMe)8(bta)7(MeOH)5(H2O)Cl8] structure that results from non-solvothermal synthetic methods, highlighting the importance of temperature regime in cluster synthesis. Magnetic studies reveal the {Fe14} complexes to have ground state electronic spins of S相似文献
65.
Choonyian Haw Weesiong Chiu Noor Hamizah Khanis Saadah Abdul Rahman Poisim Khiew Shahidan Radiman Roslan Abd-Shukor Muhammad Azmi Abdul Hamid 《天然气化学杂志》2016,(4):691-701
Current study reports a rapid one-pot non-hydrolytic condition in the synthesis of Sn O2 QDs nanopowder using tin(II) stearate(Sn(St)2) as environmentally-benign organometallic precursor,which is an unprecedentedly employed-compound in preceding Sn O2 nanopowder productions.The as-synthesized Sn O2 QDs that are hydrophobic can be easily transferred from organic solvent to aqueous solution through a robust ligand exchange method.The stearate-capping ligands on the surface of QDs can be replaced by beta-cyclodextrin(β-CD) and eventually render the QDs highly water soluble,which ultimately make it exhibit bi-functionality for different liquid medium applications.Structural characterizations reveal that the bi-functional QDs are indeed well-matched with the standard rutile Sn O2 cassiterite phase without the presence of any impurities.The QDs can be interchangeably used as photocatalyst for both aqueous and non-aqueous phase,where it shows significant enhancement of hydrogen gas production as compared to that of commercial Sn O2 nanopowder. 相似文献
66.
O-Propargylic hydroxylamines undergo smooth 5-endo-dig cyclisations upon exposure to 3 equiv of molecular iodine to give respectable yields of the corresponding 4-iodo-2,5-dihydroisoxazoles, which should find a number of applications as intermediates for syntheses amongst this useful class of heterocycles. 相似文献
67.
Opium samples from four different locations and poppy straw from different plant varieties have been assayed using micellar capillary electrophoresis incorporating a sweeping technique. Individual alkaloids (morphine, codeine, papaverine, noscapine, thebaine, oripavine, reticuline and narceine) were quantitatively determined in the different samples by a validated capillary electrophoresis method. Unsupervised pattern recognition of the opium samples and the poppy straw samples using hierarchical cluster analysis (HCA) and principal component analysis (PCA), showed distinct clusters. Supervised pattern recognition using soft independent modelling of class analogy (SIMCA) was performed to show individual groupings and allow unknown samples to be classified according to the models built using the CZE assay results. 相似文献
68.
Greaves SJ Flynn EL Futcher EL Wrede E Lydon DP Low PJ Rutter SR Beeby A 《The journal of physical chemistry. A》2006,110(6):2114-2121
The torsional motions of jet-cooled 1,4-bis(phenylethynyl)benzene (BPEB), a prototype molecular wire, were studied using cavity ring-down spectroscopy in the first UV absorption band (316-321 nm). The torsional spectrum of 1,4-bis(phenylethynyl)-2,3,5,6-tetradeuteriobenzene was also recorded in the gas phase. Both spectra were successfully simulated using simple cosine potentials to describe the torsional motions. The ground-state barrier to rotation was estimated to be 220-235 cm(-1), which is similar to that of diphenylacetylene (tolane). Complementary DFT calculations were found to overestimate the torsional barrier. 相似文献
69.
An HPLC assay for the determination of ketoconazole in common pharmaceutical preparations 总被引:3,自引:0,他引:3
An HPLC method is described using octadecylsilica (3 microns) with an acetonitrile phosphate buffer mobile phase containing diethylamine which is capable of separating ketoconazole [(+/-)-cis-1-acetyl-4-(4[2-(dichlorophenyl)-2- (1H-imidazol-1-ylmethyl)-1,3-dioxolan-4-yl]methoxy]phenyl)pi perazine] from four related compounds, (R049223, R063600, R053165 and R039519) and from excipients in tablets, cream and shampoo. The method was validated using an external calibration method for tablets, shampoo and creams and a standard addition method for cream. The limits of detection for the related compounds in the presence of ketoconazole are also reported. 相似文献
70.
Synthetic erythropoietic proteins: tuning biological performance by site-specific polymer attachment
Chen SY Cressman S Mao F Shao H Low DW Beilan HS Cagle EN Carnevali M Gueriguian V Keogh PJ Porter H Stratton SM Wiedeke MC Savatski L Adamson JW Bozzini CE Kung A Kent SB Bradburne JA Kochendoerfer GG 《Chemistry & biology》2005,12(3):371-383
Chemical synthesis in combination with precision polymer modification allows the systematic exploration of the effect of protein properties, such as charge and hydrodynamic radius, on potency using defined, homogeneous conjugates. A series of polymer-modified synthetic erythropoiesis proteins were constructed that had a polypeptide chain similar to the amino acid sequence of human erythropoietin but differed significantly in the number and type of attached polymers. The analogs differed in charge from +5 to -26 at neutral pH and varied in molecular weight from 30 to 54 kDa. All were active in an in vitro cell proliferation assay. However, in vivo potency was found to be strongly dependent on overall charge and size. The trends observed in this study may serve as starting points for the construction of more potent synthetic EPO analogs in the future. 相似文献