High-resistance phase and low-resistance phase in 1,6-diaminopyrene-p-chloranil (DAP-CHL)

A combination of DAP and CHL gives two kinds of 1:1 charge transfer complex crystals from the benzene solution. Both of them are electrically insulating at the initial states. The α-form single crystal, however, undergoes an irreversible conductivity change upon mild heating or fracture of the crystal. In both cases, the conductivity change amounts to 106 to 107, and the resultant solids are a highly conducting semiconductor. The structural, optical, magnetic, and solid-state NMR studies suggest that the low-resistant phase is mainly composed of the neutral molecules despite its high conductivity.