A multi-state supramolecular switch realized <i>via</i> a [π⋯π] dimer

Supramolecular assemblies have attracted great attention in the latest studies of molecular electronic devices for their superiorities. Here, we design a non-covalent [π⋯π] dimer made of DCV4Ts (two-terminally dicyanovinyl-substituted quaterthiophenes), and five typical conformations of this dimer are specifically focused on. Based on density-functional theory calculations and the non-equilibrium Green's function technique, electron transport properties through the dimer are mainly investigated in molecular junctions. It is revealed that four distinct states of conductance can be observed through these five conformations, with the maximal ON/OFF ratio over 400 and the minimal one around 10. The multiple states of conductance basically stem from the destructive quantum interference and the spatial overlap of the two DCV4T monomers. To implement the above-indicated molecular switch in experiments, it is essential to mechanically stretch or compress the designed dimer, probably using the piezo-modulated scanning tunneling microscope based break-junction technique.