Jozef Hodyl PhD Thesis - Theses - Flinders University

metal ion coordination the pendant arms of the ligand project away from the sameface of the cyclen framework forming a cavity large enough to include smallmolecules. 93-96, 166, 186 It is also well established by these studies that, with the ligandsexamined, cadmium(II) forms decidedly stable eight-coordinate complexes with ahigh level of rigidity. Therefore, the metal ion selected to form the receptor modelcomplex was cadmium(II).2.7.2 Synthesis of the cadmium complex of the receptor modelThe model macrocyclic receptor cadmium(II) complex, 49, was synthesised by an94, 186established method as reported by Smith, Scheme 2.10.51 49Scheme 2.10 Synthesis of the molecular analogue cadmium(II) diperchlorate complex 49.An ethanolic solution of cadmium perchlorate hexahydrate, in excess, was addedto a refluxing solution of the receptor precursor 51 also in ethanol causing an initialprecipitate that redissolved upon refluxing for a further hour. After cooling thesolution a fine off-white solid formed that was filtered and washed with cold ethanolto give 49 in 91% yield. Characterisation of 49 was by microanalysis and 13 C NMRspectroscopy, which revealed resonances in the spectrum shifted slightly downfieldcompared to those observed with the free ligand.Before proceeding with anion inclusion studies (Chapter 3) with receptor 49,50