Structural Trends in Calix[4]arene-Supported Cluster Chemistry

Methylene-bridged calix[4]arenes are incredibly versatile building blocks for the construction of polymetallic clusters of 3d and/or 4f metal ions that possess fascinating magnetic properties. The first section of this chapter reviews structural/assembly trends observed in calix[4]arene-supported cluster chemistry before discussing associated empirical metal ion binding rules. Discussion then moves to analogous cluster chemistry performed with bis-calix[4]arenes, the subunits of which are linked directly via the methylene-bridge position. Structural parallels are drawn between the calix[4]arene/bis-calix[4]arene building blocks, and in all cases common fragments/complexes are found to cap polygonal shapes. The final section of the chapter focuses on the effects of variation in tethers used to link calix[4]arenes. This affords either flexible or rigid bis-calix[4]arenes that have been used in cluster formation and the assembly of a new metal-organic polyhedron, all of which builds on established metal ion binding rules and polygonal capping behaviour.