Conical cavitands as second coordination spheres and protecting environments. towards metal-centred, intra-cavity reactions

Metallocavitands are coordination compounds based on rigidified molecular cavities which possess at least one entry. Those in which the metal centre is rigidly held above the entrance are particularly promising for the study of host-guest interactions between metal-bonded substrates and the internal part of a cavity. Such systems also open the way to highly selective intra-cavity reactions. The present review focusses on conical cavities derived from calixarenes and cyclodextrins and examines their possible use as second coordination sphere ligands.