Anion binding studies with responsive lanthanide complexes

Abstract

The binding of a range of biologically prevalent anions to several novel lanthanide(III) complexes has been studied by emission spectroscopy, (^1)H-NMR and mass spectrometry. In each case, the resultant solution adduct and the mode of anion binding was characterised through analysis of spectral response. Following the first chapter, in which relevant background work and literature reports are discussed, the novel lanthanide(III) complexes described herein are separated into three chapters. Chapter 2 describes a range of complexes bearing a pendant azaxanthone or aza-thioxanthone derived chromophore. Binding of anions was examined largely through sensitised emission, additionally the cellular localisation and toxicity profiles of each complex was studied. Of particular interest was the discovery of a family of complexes that localised within the mitochondria of the cell lines examined, and exhibited pC0(_2) dependent luminescence, notwithstanding protein quenching. Chapter 3 describes the synthesis and evaluation of two stereoisomeric dimeric complexes, in which the conformation of each was controlled by the differing relative stereochemistry of their linking unit. A range of luminescence and NMR studies was performed to establish the relative affinities of these complexes for selected anionic species, and to compare their binding properties to that of the related monomeric complex. Chapter 4 describes the immobilization of two related complexes onto various solid-phase supports. The ability of the immobilized complexes to selectively bind to, retain then release phospho-anions on addition of a competitive aqueous anionic buffer is examined. The utility and advantages of using such materials as tools for the enrichment of phospho-peptides is discussed in relation to previously published procedures and materials.