Molecular design of organic ferrimagnets

Two kinds of molecular design for genuinely organic molecule-based ferrimag netics are reported. (I) The coulombic interaction between an anion and a c ation is utilised for co-crystallizing organic radical molecules with diffe rent spin quantum numbers. This is referred to "organic salt ferrimagnetics ". A phenol derivative of nitronyl nitroxide pi -biradical with S=1 has bee n synthesised as an anionic component of the salt and the electronic spin s tructure characterized. (II) The phenolic pi -biradical with S=1 and a carb oxyl-substituted pi -radicals with S=1/2 have been esterified to give model compounds for "single-component ferrimagnetics". Potentialities of the mod el compounds as building blocks of molecule-based ferrimagnetics have been examined by susceptibility and ESR measurements.