Rational Construction of Molecular Electron-Conducting Nanowires Encapsulated in Proton-Conducting Matrix in a Charge-Transfer Salt

Insulated molecular wires have gained significant attention owing to their potential contribution to the fields of nanoelectronics and low-dimensional chemistry/physics. This study demonstrates, for the first time, the rational construction of molecular electron-conducting wires encapsulated in a proton-conducting matrix via the use of a molecular charge-transfer salt, which may pave the way for iono-electronics. As expected from the molecular structure of the newly designed complex anion (a propeller-shaped structure with hydrogen-bonding sites at four edges), a three-dimensional hydrogen-bonded framework was constructed within the crystal, which contained one-dimensional arrays of the electron donor, tetrathiafulvalene (TTF). Single-crystal crystallographic and spectroscopic studies clarified that non-stoichiometric deprotonation of anions and partial oxidation of TTF molecules occurred, whereas the anion was electronically inert. The moderate conductivities of electrons and protons were confirmed by DC- and AC-conductivity measurements. In addition, electronic isolation of the TTF wires was confirmed using magnetic susceptibility data.