Controlling the unpaired electron by electrostatic attraction in the solid state.

One-electron reduction of 2,7-tBu2-pyrene-4,5,9,10-tetraone (1) with potassium afforded two monoradicals 1K(cryp) and 1K(18c6), a radical tetramer [1K(15c5)]4 and a radical polymer (1K)2n. Using 1K(cryp) and 1K(18c6), we demonstrated large spin density modulation of an organic radical anion in the solid state by electrostatic attraction, without alternation of the molecular skeletons.