Anion recognition by ruthenium II bipyridyl receptors

CV and SWV were used to investigate the electrochemical anion recognition properties of these species in acetonitrile and the results are summarized in Tables 21 and 22. With reference to the known electrochemical properties of [Ru(bipy)3][PF6]2, the respective reversible oxidation and reduction redox couples exhibited by the receptors can be assigned to the metal-centred 

The novel results of electrochemical experiments with receptor [92] are particularly interesting. When an equimolar mixture of H2PO4, HSOJ and Cl- (each 5 x 10 4 mol dm-3) was added to an acetonitrile solution of [92] (5 x 10 4 mol dm-3), the ligand-centred reduction couple shifted cathodically by 175 mV (a shift similar to that caused by the presence of H2PO4 alone). 

Tliis was found still to be the case when the other anions were in a tenfold excess over H2PO4, showing conclusively that [92] is acting as a selective H2PO4 amperometric sensor. 

---