Abstract
Electrocrystallisation of BEDT-TTF (bis(ethylenedithio)tetrathiafulvalene) with indigo carmine provided the salt (BEDT-TTF) 3 (indigodisulfonate)•4H 2 O, in which BEDT-TTF molecules form twisted face-to-face trimers. Each trimer is sandwiched by indigo molecules and interacts with other trimers along the side-by-side direction to form a quasi-1D conducting column.The salt is a semiconductor with ρ RT = 27 Ω•cm and E a = 0.019 eV. The molecular charges, estimated using bond lengths, and the temperature-dependent magnetic susceptibility suggests that the two spins associated with each trimer do not form a spin dimer and are located on both edge molecules. A decrease of magnetic susceptibility from 100-20 K was observed, which can be fitted to a Spin Ladder model. A first-principles electronic-band calculation provides rounded quasi-1D Fermi surfaces, indicating more of 2D nature, which suggests that the charge carriers can be transported via indigo skeletons.