LAYING TRAPS FOR ELUSIVE PREY - RECENT ADVANCES IN THE NONCOVALENT BINDING OF ANIONS

The structure and function of a new class of host molecules for the su pramolecular complexation of anionic guest species are analysed within the context of other recent advances in the field, In particular, org anometallic hosts based upon the calixarenes, and the related macrocyc le cyclotriveratrylene (CTV), are examined, X-Ray crystallographic res ults clearly demonstrate the inclusion of anionic guest species such a s BF4-, I-, CF3SO3-, ReO4- etc, within the ostensibly electron-rich bo wl-shaped cavities of both types of host as a result of cooperative ef fects arising from the presence of two or more metal centres arranged around a common binding pocket, Solution radiochemical studies show th at hosts based upon CTV in particular are selective for large tetrahed ral anions such as MO(4)- (M = Tc, Re), It is anticipated that the abi lity to discriminate between anions on a size and shape selective basi s by means of manipulation of host cavity dimensions will pave the way towards new sensor devices and methods of environmental waste remedia tion.