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51.
52.
Jacqueline M. Thorpe Roy L. Beddoes David Collison C. David Garner Madeleine Helliwell Jeremy M. Holmes Peter A. Tasker 《Angewandte Chemie (International ed. in English)》1999,38(8):1119-1121
A tetranuclear iron cluster is the principal component of the purple coatings produced by treating a mild steel surface with a salicylaldoxime corrosion inhibitor. This was shown by comparison of the spectroscopic data with those of the cluster [{Fe(salH)(HsalH)}4], which was obtained from FeCl3 and salicylaldoxime (H2salH) and has a distorted tetrahedral arrangement of FeIII atoms coordinated by terminal (1−) and bridging (2−) salicylaldoximate ligands (the central core of the cluster is depicted). 相似文献
53.
Robert E. Berry Elaine M. Armstrong Roy L. Beddoes David Collison S. Nigar Ertok Madeleine Helliwell C. David Garner 《Angewandte Chemie (International ed. in English)》1999,38(6):795-797
Fly agaric accumulate vanadium in the form of amavadin, whose structure has been elucidated (see picture for the crystal structure). Amavadin contains one VIV center coordinated to two (S,S)-hidpa3− ligands (H3hidpa=2,2′-(hydroxyimino)dipropionic acid) through one η2-NO− group and two unidentate carboxylato groups from each ligand. The arrangement of the two η2-NO− groups leads to a chiral vanadium center, which has been characterized in both the Λ and Δ forms. The carboxylato groups of the amavadin anions bind cations, for example, Ca2+ ions, and/or become involved in hydrogen bonding. 相似文献
54.
The single X-ray structures of the thiosemicarbazide complexes [Cd(NH2CSNHNH2)Cl2]n·H2O (A) and [Cd(NH2CSNHNH2)2Cl2]n (B) are reported. Both compounds have been found to be effective as single source precursors for the preparation of CdS nanomaterials. Thermal decomposition of the precursors in hexadecylamine (HDA) results in the formation of nanorods of different dimensions. The powder X-ray diffraction patterns of the nanodimensional materials reveal differences in the phases of the CdS synthesized from the two complexes. The particles synthesized from both precursors show quantum confinement effects in their absorption spectra, with the evidence of a broad defect emission in their photoluminescence spectra. 相似文献
55.
Elizabeth Diesel Madeline Schreiber Jan Roelof van der Meer 《Analytical and bioanalytical chemistry》2009,394(3):687-693
Arsenic contamination of natural waters is a worldwide concern, as the drinking water supplies for large populations can have
high concentrations of arsenic. Traditional techniques to detect arsenic in natural water samples can be costly and time-consuming;
therefore, robust and inexpensive methods to detect arsenic in water are highly desirable. Additionally, methods for detecting
arsenic in the field have been greatly sought after. This article focuses on the use of bacteria-based assays as an emerging
method that is both robust and inexpensive for the detection of arsenic in groundwater both in the field and in the laboratory.
The arsenic detection elements in bacteria-based bioassays are biosensor–reporter strains; genetically modified strains of,
e.g., Escherichia coli, Bacillus subtilis, Staphylococcus aureus, and Rhodopseudomonas palustris. In response to the presence of arsenic, such bacteria produce a reporter protein, the amount or activity of which is measured
in the bioassay. Some of these bacterial biosensor–reporters have been successfully utilized for comparative in-field analyses
through the use of simple solution-based assays, but future methods may concentrate on miniaturization using fiberoptics or
microfluidics platforms. Additionally, there are other potential emerging bioassays for the detection of arsenic in natural
waters including nematodes and clams. 相似文献
56.
Decision makers select employees for a project to match a particular set of goals pertaining to the multiple criteria mix of skills and competencies needed. Cognitive style influences how a person gathers and evaluates information and consequently, provides skills and competencies toward problem solving. The proposed fuzzy set-based model facilitates the manager’s selection of employees who meet the project goal(s) for the preferred cognitive style. The paper presents background information on cognitive styles and fuzzy logic with an algorithm developed based on belief in the fuzzy probability of a cognitive style fitting a defined goal. An application is presented with analysis and conclusions stated. 相似文献
57.
Low DM Rajaraman G Helliwell M Timco G van Slageren J Sessoli R Ochsenbein ST Bircher R Dobe C Waldmann O Güdel HU Adams MA Ruiz E Alvarez S McInnes EJ 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(5):1385-1396
The synthesis and crystal structures of a family of decametallic Cr(III) "molecular wheels" are reported, namely [Cr10(OR)20(O2CR')10] [R' = Me, R = Me (1), Et (2); R' = Et, R = Me (3), Et (4); R' = CMe3, R = Me (5), Et (6)]. Magnetic studies on 1-6 reveal a remarkable dependence of the magnetic behaviour on the nature of R. In each pair of complexes with a common carboxylate (R') the nearest neighbour CrCr magnetic exchange coupling is more antiferromagnetic for the ethoxide-bridged (R = Et) cluster than for the methoxide analogue. In complexes 2, 4 and 6 the overall coupling is weakly antiferromagnetic resulting in diamagnetic (S = 0) ground states for the cluster, whilst in 1 and 5 it is weakly ferromagnetic thus resulting in very high-spin ground states. This ground state has been probed directly in the perdeuterated version of 1 ([D]1) by inelastic neutron scattering experiments, and these support the S = 15 ground state expected for ferromagnetic coupling of ten Cr(III) ions, and they also indicate that a single J-value model is inadequate. The ground state of 5 is large but not well defined. The trends in J on changing R are further supported by density functional calculations on 1-6, which are in excellent agreement with experiment. The very large changes in the nature of the ground state between 1 and 2, and 5 and 6 are the result of relatively small changes in J that happen to cross J = 0, hence changing the sign of J. 相似文献
58.
59.
H. N. Khan S. Ali S. Shahzadi M. Helliwell 《Russian Journal of Inorganic Chemistry》2012,57(5):665-670
New chloromono- and diorganotin(IV) complexes of 4-methyl-1-piperidine dithiocarboxylic acid have been synthesized in anhydrous chloroform. The complexes were characterized by microanalysis, IR, 1H and 13C NMR, mass spectrometry and XRD. The FTIR spectra clearly demonstrate that organotin(IV) moieties react with [S,S] atoms of the ligand. Compound (1) and (3) exhibits the 5-coordinated while the compound (2) exhibit 6-coordinated geometry in solid state. Compound (3) shows distorted trigonal bipyramidal geometry which is confirmed by X-ray single-crystal diffraction. 相似文献
60.
Znabet A Blanken S Janssen E de Kanter FJ Helliwell M Turner NJ Ruijter E Orru RV 《Organic & biomolecular chemistry》2012,10(5):941-944
An efficient combination of MAO-N-catalyzed desymmetrization of cyclic meso-amines with Ugi-Smiles multicomponent chemistry produced optically pure N-aryl proline amides. This method represents the first report of a fully asymmetric Ugi-Smiles process. 相似文献