Chiral Semiconductor Phases: The Optically Pure D₃[M^III(<i>S</i>,<i>S</i>-EDDS)]₂ (D = TTF, TSF) Family

A new family of optically pure tetrathiafulvalenium and tetraselenafulvalenium salts, D3[MIII(S,S-EDDS)]2·nH2O (where D = TTF, TSF; M = Co, Fe, Cr; EDDS = ethylenediaminedisuccinato), were synthesized electrochemically. These phases are semiconductors with conductivities between 6.9 × 10−6 and 1.3 × 10−5 S·cm−1 (Ea ca. 0.3 eV) for TTF and 2.8 × 10−4 to 2.8 × 10−5 S·cm−1 (Ea ca. 0.1 eV) for TSF compounds. While some crystals suffer from twinning, other well resolved structures consist of TTF/TSF stacks which, under the influence of the chiral anion, exhibit a periodic undulation described by an elliptical helix. The crystallographic data, along with computational work, indicate charge localization in the semiconducting motifs.