High-spin organic molecular materials

High-spin organic molecular materials are recent subjects of active studies. In diradicals and radical pairs, the ground states are usually singlet due to the overlap of the orbitals containing the unpaired electrons. When the singly occupied orbitals are orthogonal to each other, triplet states become ground states. Thanks to the promotion of our understanding of how to stabilize the triplet relative to the singlet, a number of examples of purely organic assemblies of free radicals and oligo/polyradicals have been accumulated, in which more than two electron spins are aligned in parallel. Approaches toward high TC and tunable organic molecule-based magnets are in steady progress.