Sorption of yttrium, lanthanum and cerium (III) ions on Zeo-Karb 225 (SRC 15) and De-acidite from perchlorate media has been studied at 25 C and a tracer concentration of the ions concerned. It has been found that the sorption of these ions on the resins in question follows nearly an identical pattern, and that the changes of the hydrogen-ion concentration in the pH range of 2.5-4 have only a very slight effect on the values of the distribution co-efficients. Taking yttrium-glycollate as a representative for the systems involving glycollate or other ligands and the triva-lent rare-earth ions and those from the actinium series using yttrium-91 as a tracer and a perchlorate medium of μ = 0.50M, the effect of the cross-linking of a resin on the β(_n) values of the system in question has been studied and found to be negligible for the 2%, 4-5%, and 8% DVB resins provided the necessary corrections due to swelling of the resins are duly taken into account. An investigation of the same system with Zem-Karb 225 (SRC 15) at different v/m ratios in the range of 15/0.20 and 15/0.60 has revealed that subject to the appropriate corrections due to swelling of the resin having been made, such changes of the v/m ratio have no significant effect on the values of the system concerned. It has been further observed that a treatment of a complexing solution with resins of different cross-linking practically entails no significant loss of the ligand species (glycollate) from the complexing solution. Having made the above investigations of the resin/solution behaviour in perchlorate media at 25 C, the method (cation-exchange) was adopted for a tracer study of the systems involving yttrium, lanthanum, cerium (III),europium (III), actinium and americium (III) ions and chloride, fluoride, sulphate, oxalate, -hydroxyisobutyrate and glycollate ligands. The stability constants have been computed by a graphic method based on a theory proposed by Fronaeus (^78,102). The results obtained are generalize in good agreement with those reported by other workers as a result of their investigation of the systems in question by ion-exchange, solvent-extraction, pH or potentiometric methods under comparable conditions, and have further shown the dependence of the chemistry of the concerned ions on the sizes of their respective crystal ionic-radii. The ratios of the β(_I) values for the lanthanum/ actinium and europium (III)/americium (III) systems involving sulphate, oxalate and α-hydroxyisobutyrate ligands have been worked out and found to be in general near unity; this is an evidence in support of similar interactions between the metal ions of both the lanthanum and actinium series and the noted ligands in aqueous systems.

The luminescence properties of cyclometallated iridium(III) complexes render them of interest, for example, as phosphorescent dopants in organic light-emitting devices (OLEDs), as photoactive units in solar energy conversion, and as biosensors. The vast majority comprise three bidentate ligands, archetypal examples being Ir(ppy)3 and [Ir(ppy)2(bpy)]+ (ppy = 2-phenylpyridine; bpy = 2,2'- bipyridine). The work described here explores the chemistry of iridium(III) complexes that contain a terdentate cyclometallating ligand. Most of the complexes studied have the general formula Ir(N^C^N)(N^C)X, where N^C^N represents a terdentate ligand based on 1,3-di(2-pyridyl)benzene; N^C a bidentate ligand such as ppy; and X is a monodentate ligand such as chloride, cyanide, thiocyanate or an acetylide. The synthetic methodology developed involves reaction of the N^CH^N proligand with iridium(III) chloride to give a dimer of the form [Ir(N^C^N)Cl(-Cl)]2, which is cleaved upon treatment with a bidentate N^CH ligand. The one remaining chloride ligand can then be exchanged for other monodentate ligands through silvercatalysed metathesis. Most of these complexes are highly luminescent, with quantum yields in degassed dichloromethane at room temperature between 0.2 and 0.9. The effect of substituents in both the aryl and pyridyl rings of the terdentate and bidentate ligands has been investigated, together with the influence of X. The emission energy has been shown to vary over a very wide range, from the blue to red regions (max = 456 to 667 nm). The trends have been partially rationalised using time-dependent density functional theory and cyclic voltammetry. Some complexes have been incorporated into multi-layer OLEDs that display unusually high efficiency, particularly for the red-emitting devices. Selected rhodium(III) analogues have been prepared, together with related iridium(III) complexes incorporating bidentate N^N (bpy) ligands. A preliminary investigation into the utility of these complexes for the construction of multimetallic assemblies has been made, through the introduction of bridging ligands into position X.

Lyoluminescence, which is the emission of light on dissolution of a previously gamma-irradiated solid, is known to depend critically on the concentrations of free radicals generated in the solid. The identity of these and the final emitting species is not yet known with certainty. The present study uses spin trapping to identify the radicals which are present on dissolution of irradiated amino acids and carbohydrates in water. The synthesis and trial of several water soluble nitroso and nitrone spin traps was carried out. 2-Methyl-2-nitrosopropane (MNP), 2-methyl-2-nitroso-4'(4'-pyridyl-1'-oxide)-butane (MNPOB) and 3,5-dibromo-4-nitrosobenzenesulphonic acid (DBNSA) were found to be the most useful. Using these traps, radicals present in solution after dissolution of gamma-irradiated amino acids were identified as (a), deaminated radicals or (b), hydrogen abstraction radicals. The e.s.r. spectra obtained in the same way with irradiated carbohydrates were more complex than those with the amino acids. The trapped radicals were identified mainly as secondary alkyl radicals which were produced in the solid by rearrangement or fragmentation of the initially formed, mainly tertiary alkyl radicals. Radicals trapped from model systems, in which the initially-formed radicals were produced by hydrogen abstraction from carbohydrates and polyhydric alcohols, usually arise via acid-catalysed dehydration. Hydrogen abstraction from cyclic ethers in the presence of spin traps also gave results that could be explained in terms of rearrangement or fragmentation of the initially formed radicals. However, none of the above systems was found to model the gamma-irradiation of carbohydrates in the solid state. The final emitting species was investigated by recording the transient emmission spectra of lyoluminescence. Evidence was obtained for the involvement of triplet carbonyls in amino acid lyoluminescence and in carbohydrate lyoluminescence at high pH, and for singlet oxygen in carbohydrate lyoluminescence in water. In the presence of sensitisers, the lyoluminescence spectrum became characteristic of the sensitiser. Correlations were obtained between light yield, solid state radical concentration and trapped radical concentration for L-glutamine and L-alpha-alanime. The effects of annealing on glutamine were explained in terms of destruction of a particular type of radical which led to a reduction in the proportion of radical-radical reactions in solution and for alanine by a diffusion of oxygen into the crystal lattice. No evidence for the formation of peroxyl radicals in the solid was obtained.

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