| Popis: |
It was at the turn of this century, within the area of co-ordination chemistry that the interdependence of structure and reactivity was first realised. The understanding of interactions between metal and ligand has become more complex progressing from simple unidentate to the more complicated multidentate systems and in some instances, ligand designs have imposed unusual co-ordination geometrics around metal atoms. Such offsets are particularly evident in macrocyclic ligands. Their intrinsic properties as ligands gives them the potential to behave as catalysts, semiconductors and sequestering agents for use in pollution control and hydrometallurgy. In addition, they have impinged on the biomedical field, where they have become likely candidates for therapeutic reagents required for the treatment of metal intoxication, or used as diagnostic agents in the form of radio-labelled macrocycle-conjugated antibodies for better tumor imaging while their specificity and efficacy prove excellent for enzyme modelling. In 1987, achievements in this expanding field culminated in the form of a Nobel prize, awarded to C. J. Pedersen, J. M. Lehn and D. J. Cram and marked the scientific world's recognition of the importance of macrocyclic chemistry. Having briefly outlined the wealth of research associated with macrocyclic ligands currently being undertaken, one aspect is of special interest to this work. The objective of this project has been to design new selective complexing agents for the toxic heavy metal ions cadmium(II), mercury(II) and lead(II). Resulting observations on the properties of such systems should provide a better insight of how and why certain ligands 'discriminate' or appear selectively to complex with only certain metal ions. In addition, the project supplements an ongoing study of related work which forms part of a series within a matrix of similar macrocyclic ligands. |
