| Research Abstract |
In order to prepare a single-molecular magnetic device that can change their spin-states corresponding to stepwise reduction (or oxidation), we tried to synthesize such the organic magnetic molecules having two parts in a molecule; one part can be reduced easily to give a radical anion (or oxidized easily to give a radical cation), and another part has open-shell structure. Thus, we proposed quinines bearing two nitronylnitroxide (NN) moieties.
Density functional theory (DFT) calculations for these molecules at various reduction/oxidation states indicate that hydroquinone bearing two NN moieties at 2,5-positions (and its dimethoxy ether) is a ground-state singlet biradical molecule. The semiquinoneradical, however, has a quartet as its ground-state.
The biradicals, 2,5-bis(4,4,5,5-tetramethylimidazoline-2-yl)-1,4-dimethoxybenzene and 2',5'-dimethoxy-4,4"-bis(4,4,5,5-tetramethylimidazoline-2-yl)-p-terphenyl were obtained from corresponding aldehydes and 2,3-diamino-1,4-dimethylbutane, followed by the oxidation with m-CPBA - NaIO_4. Crystal structure of the former diradical (reddish-purple) was solved. Bis(t-buthyldimethylsilyl)ether of the diradical was also synthesized to obtain the hydroquinone. Synthesis of bisquinone NN-diradicals and the Mn(II)-complexes is in progress.
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