Robert J. Lancashire

Bio: Robert J. Lancashire is an academic researcher from Cardiff University. The author has contributed to research in topics: Circular dichroism & Acid dissociation constant. The author has an hindex of 5, co-authored 6 publications receiving 127 citations.

Isomers of α-amino acids with copper(II). Part VI. Novel equilibria at high pH in copper(II):Amino-acid solutions

Abstract: Circular dichroism spectra show the presence at high pH of a new pH-dependent equilibrium for aqueous solutions of amino-acid with copper(II) ions. Measurements are interpreted in terms of an apparent acid dissociation constant. A typical value for pKa is 12.17 for alanine. Electron spin resonance and circular dichroism suggest that the high pH form is a monomeric hydroxobisalaninato-complex of copper(II).

Equilibria in complexes ofN-heterocyclic molecules, Part XXIV. The reaction of nucleophiles with tris-(2,2′-bipyrimidine)iron(II) ion and its ruthenium(II) analogue

Abstract: The reactions of [Fe(bipym)3]2+ and [Ru(bipym)3]2+ with hydroxide ion in aqueous solution have been followed. The [Ru(bipym)3]2+ species undergoes nucleophilic attack at the ligand to yield [Ru(bipym)2(pyrimidine)(OH)]+ and [HCO2]− ion, involving cleavage of one pyrimidyl ring. Intermediates can be observed in the reaction of [Fe(bipym)3]2+ with HO−, N3− and SCN−. The kinetics of the first reaction have been followed and the results are compared with those known for the reactions of [Fe(bipy)3]2+, [Fe(phen)3]2+ and similar compounds.

The chemistry and biochemistry of vanadium and the biological activities exerted by vanadium compounds.

Abstract: 6.1.2. Aqueous V(III) Chemistry 877 6.1.3. Oxidation State of Vanadium in Tunicates 878 6.1.4. Uptake of Vanadate into Tunicates 879 6.1.5. Vanadium Binding Proteins: Vanabins 879 6.1.6. Model Complexes and Their Chemistry 880 6.1.7. Catechol-Based Model Chemistry 880 6.1.8. Vanadium Sulfate Complexes 881 6.2. Fan Worm Pseudopotamilla occelata 883 7. Vanadium Nitrogenase 883 7.1. Nitrogenases 883 7.2. Biochemistry of Nitrogenase 884 7.3. Clusters in Nitrogenase and Model Systems: Structure and Reactivity 885

Homoleptic Complexes of 2,2′-Bipyridine

Abstract: Publisher Summary This chapter offers information on homoleptic complexes of 2,2'-bipyridine (bpy). The chapter focuses on the class of complexes that contain only bpy ligands bonded to the metal. The unique metal-binding properties of bpy were recognized from the outset. The third renaissance in bpy chemistry can be traced to the commercial availability of the ligand in the 1950s, when large amounts were required for the preparation of Diquat insecticides. The current interest in complexes of bpy is associated with the extremely interesting electrochemical, photophysical, and photoelectrochemical properties that they exhibit. 2,2'-Bipyridine is a strong field ligand that forms relatively stable complexes, with the inherent M–N bond strength enhanced by the chelate effect. Complexes with main group metal ions, and with lanthanides and actinides, can be prepared in water or organic solvents. The bis complexes are known for a range of metals and oxidation states though they tend to be more common for lower formal oxidation states. The bpy ligand is remarkable for the wide range of formal oxidation states with which it is associated. The chapter discusses the general trends in the reactivity of specific complexes under the appropriate elements. Iron, ruthenium, and osmium have played a crucial role in the development of the chemistry of 2,2'-bipyridine.

Characterization of Starburst Dendrimers by the EPR Technique. Copper(II) Ions Binding Full-Generation Dendrimers

Abstract: Cu(II) was used as a probe to investigate the structure and ion binding ability of full-generation poly(amidoamine) starburst dendrimers (nSBDs). Computer-aided analysis of the EPR spectra provided information on the formation of copper complexes in various internal or external locations of the dendrimers, as well as the nSBD structure as a function of the size (generation) of the dendrimers, pH, temperature, Cu(II) concentration, and aging of the samples. At low pH, Cu2+ competes with protons for binding with external amino groups, which become available for complexation at pH > 3.5. The Cu(H2O)62+ complexes are localized in proximity to the SBD surface, where structural modifications of the water solution prevented the occurrence of a freezing transition. A portion (about 20%) of Cu(H2O)62+ resides in the water pools in the open structure of the earlier generation dendrimers (G < 4) and are capable of undergoing a freezing transition. Progressive penetration of Cu2+ ions into the SBD structure occurs wi...