Abstract
Abstract
N,N-disubstituted bis(furanyl-2-methyl)aminoanilines are new electrochemically-active probes for cations relying on the phenylenediamine moiety as an electroactive transducer and the difuranylamino group as an ionophore site. The electrochemical investigations, by means of cyclic and Osteryoung square wave voltammetries (CV and SWV, respectively), showed that these compounds are able to bind Mg
2+
, Ca
2+
, Ni
2+
and Zn
2+
cations with strong affinities. The addition of catalytic amounts of trifluoromethanesulfonic acid (TfOH) was found necessary to achieve rapid cation complexation. The electroactive redox features of the probes were drastically modified when the ionophore site was bonded to the cations. The anodic potential shifts of the oxidation peaks were between 905 and 1030 mV depending on the cations. The electrochemical investigations suggested the formation of a 1:2 stoichiometric complex: [M(L)
2
]
2+
, M=Mg, Ca, Ni and Zn. These probes were found to be selective of Ca
2+
and chelates, with strong preference for Ca
2+
even in presence of others cations (Ca
2+
> Mg
2+
, Ca
2+
> Ni
2+
and Ni
2+
> Zn
2+
). UV-visible spectrophotometric studies also showed blue shifts of the absorption bands comprising between 5 and 29 nm ligands when the metal ions were added to the solution, which confirmed the complexes formation.