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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

A molecular mechanics study for selective complexation of metal ions in medical applications

Chantson, Tracy, Elizabeth January 1994 (has links)
A dissertation submitted to the Faculty of Science University of the Witwatersrand, Johannesburg for the degree of Master of Science. Johannesburg, 1994. / Molecular mechanics calculations are used to interpret and predict metal ion discrimination by coordinating ligands. Of particular interest are chelates exhibiting characteristics that Single them out for potential medical application; Selectivity patterns for several series of ligands are investigated with the help of strain energy profiles as a function of metal-donor atom bond distance. Ligands include simple; open-chain oxygen- and nitrogen-donors ana triaza- and tetraazamacrocyeles. Results are compared with X-ray crystallographic and solution data. Factors such as chelate ring size, conformational flexibility and preferred metal coordination geometry are found to influence metal specificity. Addition of pendent donor groups to macrocyoles leads to rigid structures and selectivity predictions according to cavity size. Interpretation of specific. metal ion recognition by polyetner antibiotics is attempted. Structural and steric factors are probed as possible determinants of metal choice. both covalent and ionic bonding models are explored. The covalent approach results in predictions of metal selectivity which correlate with mown selectivity patterns. Unfortunately, inability to optimise force field parameters in the ionic bonding approach forced us to abandon this model. The main force field used is the TRIPOS (1992,1993) force field. It performs well in calculations involving a univariate scanning technique but has to be modified to obtain reasonable structure reproduction with the large antibiotics, Errors in thermodynamic data predictions are obtained, nonbonding parameters have yet to be properly parameterized and the allocation of partial atomic charges warrants closer examination . All of these factors contribute to the poor performance of the force field when ionic interactions between metal and donor atoms of the polyethers are assumed. / AC2017
42

Metal ion complexing properties of the highly preorganized ligand 1, 10-phenanthroline-2,9-dicarboxylic acid /

Dean, Nolan Edward January 2007 (has links) (PDF)
Thesis (M.S.)--University of North Carolina Wilmington, 2007. / Includes bibliographical references (Leaves: 135-136)
43

The highly preorganized ligands 8-(2-Pyridyl) Quinoline, 2,2'-dipyridyl amine and 1,10-phenanthroline-2, 9-dicarboxylic acid, and their complexing properties with metal ions

Gaver, Charles Richard January 2008 (has links) (PDF)
Thesis (M.S.)--University of North Carolina Wilmington, 2008 / Title from PDF title page (viewed May 26, 2009) Includes bibliographical references (p. 135-136)
44

Synthesis and design of fluorescence ligands to act as sensor for zinc /

Gan, Wei. January 2004 (has links)
Thesis (M.S.)--University of North Carolina at Wilmington, 2004. / Includes bibliographical references (leaves : 72-73).
45

Substitution Chemistry of the Cobalt Complexes [Co₂(CO)₆(PhC≡CR) (R=Ph, H) and PhCCo₃(CO)₉] with the Diphosphine Ligands [Bis(diphenylphosphino)maleic Anhydride (BMA) and (Z)-Ph₂PCH=CHPPh₂]. Reversible Chelate-to-Bridge Diphosphine Ligand Exchange, Phosphorus-Carbon Bond Cleavage and Phosphorus-Carbon Bond Formation

Yang, Kaiyuan 12 1900 (has links)
The tricobalt cluster PhCCo3(CO)9 (1) reacts with the bidentate phosphine ligand 2,3-bis(diphenylphosphino)maleic anhydride (bma) in the presence of added Me3NO to give the diphosphine-substituted cluster PhCCo3(CO)7(bma) (2). Cluster 2 is unstable in solution, readily losing CO to afford Co3(CO)6[(μ2-η2/η1-C(Ph)C=C(PPh2)C(O)OC(O)](μ2-PPh2) (3) as the sole observed product. VT-31P NMR measurements on cluster 2 indicate that the bma ligand functions as both a chelating and a bridging ligand. At -97 °C, 31P NMR analysis of 2 reveals a Keq of 5.7 in favor of the bridging isomer. The bridged bma cluster 2 is the only observed species above -50°C. The solid-state structure of 2 does not correspond to the major bridging isomer observed in solution but rather the minor chelating isomer. The conversion of 2 to 3 followed first-order kinetics, with the reaction rates being independent of the nature of the reaction solvent and strongly suppressed by added CO, supporting a dissociative loss of CO as the rate-determining step. The activation parameters for CO loss were determined to be ΔH≠ = 29.9 ± 2.2 kcal/mol and ΔS≠ = 21.6 ± 6 eu.
46

Oxidation chemistry of ruthenium and manganese complexes of multi-anionic chelating ligands

梁華雄, Leung, Wa-hung. January 1989 (has links)
published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy
47

Synthesis, photophysics and photochemistry of Rhenium (v) complexes with multiply-bonded nitrogen and oxygen ligands

譚國光, Tam, Kwok-kwong. January 1995 (has links)
published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy
48

Photochemical studies of binuclear platinum and rhodium complexes withbridging isocyanide, phosphite and phosphine ligands

李慧敏, Li, Huai-min. January 1989 (has links)
published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy
49

The chemistry of lanthanide complexes containing aminophenol and carboxylate ligands

林偉興, Lam, Wai-hing. January 2001 (has links)
published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy
50

Syntheses and photophysics of luminescent homo- and heterometallic complexes of rhenium(I) containing mono- and poly-ynyl ligands

Chong, Hung-fai., 莊鴻輝. January 2001 (has links)
published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

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