Ligands of the bis-(8-hydroxyquinoline) type were selected for the preparation of
semiconducting coordination polymers. After some preliminary investigations in
solvents, melt techniques with reaction temperatures of at least 250°C were found to
be necessary for the formation of a conducting product from chloranil, o-phenylene-
diamine, and a metal salt, which is postulated to involve polycoordination of a quinoxalo-
phenazine derivative. Of 13 different metals studied, the FeCl2 polymer was found to
be the best conductor, having a resistivity of 38 kΩ cm with a preparation temperature
of 350°C, the resistivity remaining at this level for preparation temperatures up to
450°C.
Studies of the reactions of the FeCl2 and FeCl3 polymers suggest intermolecular
linking other than through the metal, a t least two types of organic cross-linking being
evident. The presence of phenazinium salt structures in both polymers is postulated
to account for the large amounts of chloride ion liberated by alkali.
The conducting properties are attributed to interaction between donor nitrogens
and acceptor groups such as the metal ion, quinones, and quaternary nitrogens linked
within a fully conjugated polycyclic system. The existence of the metal in more than
one oxidation state, which might occur with the FeCl2 polymer, may be of further benefit.
Response of Phosphopyruvate Carboxylase to Tryptophan Metabolites and Metal Ions