Quantum Spin Transport through Blatter’s Di- and Tri-Radicals

A single unpaired electron in an organic molecule residing in the singly occupied molecular orbital (SOMO) renders it an organic radical. It incorporates exchange splitting in the frontier occupied and unoccupied orbitals, separating the alpha and beta-orbitals. This fact enormously impacts the electron transport properties in the organic radicals by promoting spin-polarized current and significantly enhanced conductance as compared to their closed shell counterparts. Exploring these phenomena, several mono-radicals have been investigated by molecular spintronic experiments and theories. In this work, we addressed the impact of increasing number of of radical centers on the transport properties of the multi-radical molecular species by considering di- and tri-radicals based on a stable Blatter’s radical. With the increasing number of radical centers, the number of SOMOs increases. Does the increased number of frontier SOMOs provide larger exchange splitting and better transport properties? Here, we have observed that the spatial distributions of SOMOs and their coupling with electrodes play a decisive role compared to the presence of multiple unpaired electrons in the molecular systems.