Cytosine-Substituted Nitronylnitroxide Radical:  A Key Component for Bio-Inspired Molecule-Based Magnetics

A cytosine-substituted nitronylnitroxide radical (1) was synthesized. The nucleobase moiety plays a primary role in molecular packing in the crystal. It has been found from X-ray structure analyses and magnetic susceptibility measurements that the intermolecular magnetic interactions in the crystal are propagated by orbital overlaps between the phenylnitronylnitroxide moieties of the adjacent molecules, whereas the relative arrangement of the molecules are governed by the hydrogen bonding of the nucleobase moiety, giving a doubled chain structure. The hydrogen-bonded aggregation of the cytosine-substituted radical molecules can be a useful element for molecular assembly of bio-inspired molecule-based magnets in terms of crystal engineering for nucleobase-substituted radicals.