Tetrathiafulvalene Radical Cation — A New Potent Inhibitor of Anion Transport in a Green Alga

Abstract An inhibitory effect of potassium ferricyanide on the light‐dependent active uptake of chloride anions into the alga Hydrodictyon reticulatum has drawn attention to the possibility that chloride transport proceeds as an exchange for electrons and hence can be impaired by artificial electron acceptors. Tetrathiafulvalene radical cation present in solutions of the highly conductive TTF‐C1 crystals is easily reduced to TTF 0 and inhibits the chloride uptake more powerfully than does ferricyanide. A practically complete inhibition of Cl − uptake is brought about by 3 × 10 −5 M TTF + . The presence of ferricyanide actually reduces the inhibitory effect of TTF + ; the complex equilibria of a mixture of the two electron acceptors were examined by cyclic voltammetry and a competition between the two for the inhibitory function has been suggested as a possible explanation.