First-principles study of the switching mechanism of [2]catenane molecular electronic devices.

We present a first-principles study of the coherent charge transport properties of bistable [2]catenane molecular monolayers sandwiched between Au(111) electrodes. We find that conduction channels around the Fermi level are dominated by the two highest occupied molecular orbital levels from tetrathiafulvalene (TTF) and dioxynaphthalene (DNP) and the two lowest unoccupied molecular orbital levels from tetracationic cyclophane (CBPQT4+), and the OFF to ON switching results from the energetic shifts of these orbitals as CBPQT4+ moves from TTF to DNP. We show that the superposition principle can be adopted for predicting the function of the composite device.