Synthesis and Coordination Chemistry of Ligands for Supramolecular Chemistry and Sensing Applications

A series of multidentate N-donor ligands have been synthesised all containing pyridyl and pyridyl/thiazole units and their coordination behaviour is described. The ligands are classified into four types; i) terpyridine containing pyridyl/thiazole ligands (L); ii) pyridyl/thiazole ligands containing a 3,3′-disubstituted bipyridine core. (L); iii) 2,2′-bipyridine containing a crown ether moiety (L); and iv) a 2,2′bipyridine derived ligand containing a urea functional group in the 3,3′-positions (L). Chapter II describes terpyridyl/pyridyl/thiazole ligands: the synthesis of (L) is described and the complexes ([Cu(L)][ClO4]2, [Ni(L)][ClO4]2, [Co(L)][ClO4]2, [Cd3(L)2][ClO4]6) structurally characterised. Partitioning of the ligands (L) is dependant on the position of the thiazole ring within the ligand chain. This partitioning is found to occur at a position adjacent to that of the thiazole ring in all but the L ligand complexes, where it is partitioned preferentially at a position creating favourable coordination geometry for the metal ion. Chapter III describes 3,3′-disubstituted pyridyl/thiazole ligands (L): the novel potentially hexadentate ligands (L ), the potentially octadentate ligand (L) and the potentially tetradentate ligands (L ) have been synthesized and structurally characterised. All ligands are found to partition at the central pyridine unit due to unfavourable steric interactions to form a pyridyl/thiazole/pyridyl-binding domain (L) and the pyridyl/thiazole-binding domain (L). The substituents are found to dominate the control of the formation of complexes produced ([Zn(L)][ClO4]2, [Cd(L)][ClO4]2, [Cd2(L)2][ClO4]2, [Cd2(L)2][ClO4]2). Chapter IV, Section 1 describes ditopic bipyridine/crown ether ligands: the synthesis of (L) is described and the Ru (II) complexes (L) structurally characterised. The Ru(II) complexes of these 3,3′-disubstituted crown ether species were found to luminesce. Modulation of the luminescent properties of the ruthenium complex was investigated with a selection of common cations but resulted in little or no response.