(I) We will explore the synthesis of a range of new ligand frameworks containing Group 15 elements. The principal aims in part of the research will be to:- Create a range of P/N macro cycles with varied donor functionalities, capable of potentially selective metal coordination,- Extend the synthetic methodology for P/N macro cycles to mixed-element and mixed- ligand macro cycles.
(II) We will explore the coordination chemistry of the deprotonated (or formally deprotonated) macro cyclic ligands with arrange of main group and transition metals. The main aims in this part of the research will be to:- Assess the rigidity and coordination behavior of the P/N, heteroleptic and heteroatomic macro cycles[ i. e., whether the integrity of the macro cyclic frameworks are retained in all cases after deprotonation and metal coordination or whether they may adjust in response to the metal(s ) coordinated], and how it may be turned by ligand modification.
(III) As revealed by Pro. Wright most recent study, the P/N ligand arrangements have the further ability to coordinate anions. We will explore the potential of the neutral P/N and related heteroatomic ligands to coordinate an extensive range of anions The principal aims in this part of the study will be to:
- Uncover the factors controlling the expansion of the neutral macro cycles upon coordination to anions,
- Explore the potential for selective anion coordination, i.e., "anion sensor" characteristics, and
- Assess the reversibility of anion coordination. Macrocyclic ligands in which the size of the cavity can be fitted to the size of a giving ion can afford a high selectivity in metal complexation, as shown by the pioneering work of Pedersen on crown ethers and by the more sophisticated ligands developed by Cram and Lehn, for which invention these three scientists received the Nobel prize in 1987. Appropriate macrocycles can also be selective receptors of anions. Applications of selective complexation range from analytical chemistry (sensors) to environ chemistry (extraction of toxic ions). Studies in this area will, therefore, expose the applicant to a wealth of new concepts and techniques. Most macro cyclic ligands currently used suffer from tedious, multistep preparations. In contrast, the new ligands described in the proposal can be prepared by self- assembly of simple precursors. The developing of their chemistry and applications, therefore, will add new exciting avenues to the research effort of the host group. On the other hand, this project will complement the current scientific background of the applicant by exposing her to contemporary self-assembly synthetic methods, supramolecular chemistry, host-guest complexation and sensor technology.