Preparation of silica gel-bound macrocycles and their cation-binding properties

Values of log K for the association of several metal cations with 15-crown-5, 18-crown-6, and N,N′-dibenzyldiaza-18-crown-6, each covalently bonded to silica gel, were found to be nearly the same as those for the association of the same cations with the unbound macrocycles; this observation indicates the possibility of building pre-determined cation selectivity into these permanent macrocycle-bound silica gel systems.