Investigations of the 9,10-diphenylacridyl radical as an isostructural dopant for the molecular semiconductor 9,10-diphenylanthracene

The synthesis and characterization of the 9,10-diphenylacridyl radical (2), the isostructural n-dopant for 9,10-diphenylantracene (1), are described. Crystals of 1 doped with up to 10% 2 are grown from tetrahydrofuran-heptane solutions and are single phase and isomorphous with crystals of pure 1 grown from the same solvent system. The doped crystals do not have significant room-temperature electrical conductivity, and solution-phase electrochemical measurements demonstrate why this is so. Investigations of 2 reveal that it is monomeric with one impaired electron in solution, displays unusual magnetic behavior in the solid state, and is a modest electrical conductor as a pressed pellet. The solution-phase ESR and NMR spectra of 2 are presented and interpreted.