Prediction of new donors for organic superconductors

The donors of all known one- or two-dimensional organic superconductors are based on a core organic molecule that is either tetrathiafulvalene (denoted as TTF) or tetraselenafulvalene (denoted as TSeF) or some mixture of these two molecules. Coupling X, with appropriate acceptors, Y, leads to superconductivity. The oxidized form of X may be X⁺ or X₂ ⁺ species in the crystal. From ab initio quantum mechanical calculations (HF/6-31G^**), we find that all known organic superconductors involve an X that deforms to a boat structure while X⁺ is planar. This leads to a coupling between charge transfer and the boat deformation phonon modes that we believe is responsible for the superconductivity of these materials. Based on this idea we have developed similar organic donors having the same properties and suggest that with appropriate electron acceptors they will also lead to superconductivity.