The incorporation of a Ru(bda)(bda
= 2,2′-bipyridine-6,6′-dicarboxylate)
water oxidation catalyst into a trinuclear metallosupramolecular macrocycle
leads to increased stability and activity compared to the mononuclear
reference system. To overcome solubility problems of such large structures
in water and the need for large amounts of organic cosolvents, new
macrocyclic water oxidation catalysts with improved water solubility
become desirable. With triethylene glycol side chains, the required
amount of acetonitrile as a cosolvent was halved, whereas the application
of charged ammonium side chains allowed catalysis in pure water. The
catalytic activity was found to be comparable to the parent compound.
Kinetic experiments were performed to explain the rate differences
between those new derivatives and showed that Coulombic repulsion
between the charged side chains and Ce<sup>IV</sup> leads to slower
oxidation processes
