Tuning the Magnetic Exchange Interactions in Organic Biradical Networks

Abstract

An overview of organic biradicals directed towards triplon excitations in higher ordered crystalline states is provided. The topic started from the idea to control the intramolecular spin exchange interaction in a sizable but not too large extent, in order to provide also decent intermolecular spin interactions in a crystalline lattice. The predictability of exchange couplings through DFT calculations of optimized geometries turns out to be limited, such that the molecules need to be synthesized and crystallized for further in‐depth characterizations. For crystal structure geometries, most often then a good agreement of calculated intra‐ and intermolecular exchange interactions with those later determined experimentally is found. Finally, it is demonstrated that by choosing well balanced size of both interactions a field‐induced higher ordered magnetic state becomes accessible.