New organic magnetic materials. the use of hydrogen bonds as a crystalline design element of organic molecular solids with intermolecular ferromagnetic interactions

Summary form only given. A brief description of the most relevant structural and electronic requirements in order to design purely organic ferromagnetic materials will be provided, stressing the principal advantages and limitations of the molecular solid strategy to achieve this objective. A new approach to achieve ferromagnetic interactions in such a type of materials, based on the use of hydrogen bonds with open shell molecules, will be provided. This new approach will be presented and discussed in relation with some polyhydroxylated cc-phenylnitronyl nitroxide radicals; in particular of 4- and 3-hydroxyphenyl and 3,5- and 3,4-dihydroxyphenyt a-nitronyl nitroxide radicals. The examples of radical here presented show that depending on the number and position of the hydroxyl groups, it is possible not only to control the relative molecular orientations but also to transmit magnetic interactions, either of antiferro- or ferromagnefic type, in different spatial directions.