Synthesis and properties of catechol-fused tetrathiafulvalene derivatives and their hydrogen-bonded conductive charge-transfer salts

Catechol-fused tetrathiafulvalene (TTF) derivatives have been designed and synthesized as a new type of π-electron donor molecules having two phenolic hydroxyl groups. Cyclic voltammetry measurements and quantum chemical calculations demonstrated the electronic effect of the direct fusion of the catechol unit to the TTF π-skeleton. In the charge-transfer (CT) salts with bromide or chloride anions, a one-dimensional hydrogen-bonded chain was formed by the intermolecular OH⋯X network between the catechol moieties and the halide anions. The slight dissimilarity of the hydrogen-bond distances for the two CT salts gave rise to the significant differences in their overall molecular arrangements and intermolecular interactions as well as the electrical resistivities.