Abstract

Simple bis-bidentate bridging ligands based on two chelating pyrazolyl-pyridine termini combine with transition metal dications to give a range of polyhedral coordination cages, varying from M4L6 tetrahedra to M16L24 truncated capped tetrahedra, with a metal ion at each vertex and a bridging ligand spanning every edge. Amongst these a set of M8L12 cubic cages have well-developed host-guest chemistry, able to accommodate a wide range of small molecules in the central cavity, with binding constants of up to 10E8 M-1 in water. Guest binding leads to a wide range of interesting types of behaviour, including (i) reversible uptake and release of drug molecules triggered by changes in pH; (ii) luminescence signaling of binding of chemical warfare agent simulants; and (iii) substantial catalytic acceleration with multiple turnovers of a range of reactions of bound guests.