Diamino-diamido tetrathiafulvalene for the sensing of anions and cations: a view in electrochemistry and structure.

A new cation- and anion-sensitive system based on a TTF derivative with a diamino-diamido moiety (H(2)L) has been studied. The results of cyclic voltammetry indicated that the redox potentials of the protonated H(2)L (H(4)L(2+)) selectively respond to later transition metal cations and some oxo anions. Solid-state structures of the cation-anion compounds formed by H(4)L(2+) and oxo anions were characterized crystallographically, which is helpful to understand the matter of the sensitivity for the anion. There are two types of hydrogen bonds in these compounds, one is with an amino group and the other is with an amido group. The shift of the redox potential is obviously related to formation of hydrogen bonding with the amido group. The packing structures of these cation-anion compounds are arranged to layered sandwiched structures assembled by an oxo-anion layer and two TTF layers through hydrogen bonding.