Functionalisation of silica gel with cyclic and acyclic Schiff bases and related d- and/or f-metal complexes

Two different synthetic pathways were devised in order to graft on silica gel organic moieties, containing macroacyclic or macrocyclic compartimental ligands, formed of an inner N(3)O(2), or NO, Schiff base site, able to coordinate d metal ions, and one adjacent 0,0, or 0204 crown ether-like chamber suitable for hosting f ions, in the terminal part. These materials can bind d metal ions into the amine-imine moiety. Their subsequent reaction with varying amounts of gadolinium(III) invariantly gives a system in which two grafted copper complexes coordinate only one gadolinium(III) ion with their oxygen-containing chambers, giving rise to a trinuclear Cu(2)Gd entity.