Spin in Organics
Keywords: High spin molecules, molecular magnets, redox spin switches, quantum computers
The magnetic exchange interactions in biradicals can be classified into loosely interacting spin ½ dimer, ferromagnetic (fm) exchange or antiferromagnetic (afm) exchange depending on the distance, topology, and type of the radical moiety as well as the π-conjugated system (Fig. 1). In a systematic tuning of the afm exchange interactions in the crystal lattice we found magnetic field induced 2D and 3D ordered phases at low temperatures in AC susceptibility (Fig. 2), indicating a Bose-Einstein condensate (BEC) of triplons.(210,267,269,283) The nitronyl nitroxide (NN) radicals can also be attached to liquid crystalline units or compared to other singlet biradicals where the exchange interaction is difficult to tune.
Finally we decorated the edges of graphene nanoribbons with NN and compared them to their polyphenylene precursors (Fig. 3).(276)