Pluri-dimensional hydrogen-bonded networks of novel thiophene-introduced oligo(imidazole)s and physical properties of their charge-transfer complexes with TCNQ

Novel π-extended oligo(imidazole)s composed of imidazole and thiophene ring systems, bis(imidazolyl)thiophenes , were synthesized as new building blocks for electron-donor molecules having diverse hydrogen-bonding directionalities in order to explore hydrogen-bonded charge-transfer complexes and supramolecular assemblies. The cyclic voltammetry of these compounds showed increase of electron-donating ability compared with those of 2,2′- and 4,4′-biimidazoles. In the crystal structure, , and exhibited multi-dimensional hydrogen-bonded networks via solvent molecules including the π–π interaction. Charge-transfer complexes of , and with TCNQ were characterized as partial charge-transfer complexes with segregated stacks. The compressed pellets of the TCNQ complex of showed a high electrical conductivity (σrt=5.2×10−2 S cm−1) at room temperature with semiconducting behavior (activation energy, Ea=71 meV).