Surface-Mediated Recrystallization for Highly Conducting Organic Radical Crystal

Abstract

Electrically conducting cation-charged dihydrophenazinium radical (H2PNZ•+) crystals were formed by a one-pot photoreaction. Furthermore, new secondary crystals were grown directly from the H2PNZ•+ crystal surface through a surface-mediated recrystallization (SMR) process by a secondary photoreaction with water. Depending on the absence or presence of light during the exposure of the H2PNZ•+ single crystal to water, neutral yellow PNZ crystals (SMRY) or densely packed green H2PNZ•+ crystals (SMRG) were formed, respectively, on the surface of the mother H2PNZ•+ crystal. The single-crystal X-ray analysis reveals that the newly obtained SMRG radical crystal exhibits a shorter intercolumnar distance than the original H2PNZ•+ crystal, resulting in increased electrical conductivity.