Electrochemical anion sensing using electrodes chemically modified with Au(I)-Cu(I) heterotrimetallic alkynyl cluster complexes containing ferrocenyl groups

A novel family of electrochemical anion sensors operating in aqueous media, based on the heterometallic Au (I)-Cu(I) [{Au(3)Cu(2)(C(2)R)(6)} Au(3)(PPh(2)C(6)H(4)PPh(2))(3)](PF(6))(2) (L1, R=Fc; L2, R=C(6)H(4)Fc) alkynyl cluster complexes, is presented. Upon attachment to graphite and gold electrodes, these compounds exhibit a well-defined, essentially reversible, solid-state electrochemistry in contact with aqueous media, based on ferrocenyl-centered oxidation processes involving anion insertion, leading to distinctive pH-independent electrochemical responses for fluoride, chloride, bromide, perchlorate, bicarbonate, carbonate, phosphate, hydrogen phosphate, dihydrogen phosphate, and nitrate anions. Cluster-modified electrodes can be used as potentiometric sensors as a result of the reversible, diffusion-controlled electrochemistry obtained for the anion-assisted electrochemical oxidation of L1 and L2.