Unusual electrical properties of neutral mixed-stack charge-transfer complexes of DAP-BRL (DAP = 1,6-diaminopyrene, BRL = p-bromanil)

Article abstract of DOI:10.1246/bcsj.72.21

Two polymorphs of 1:1 charge-transfer complexes of DAP-BRL were grown from a benzene solution. The γ-form is triclinic, space group P1, a = 16.53(1), b = 17.80(1), c = 8.235(5) A, α = 96.42(7), β = 97.76(6), γ = 120.79(5)°, V = 2015(3) A³, and Z = 4; the δ-form is monoclinic, space group Pn, a = 6.862(3), b = 9.891(2), c = 15.246(2) A, β = 101.78(2)°, V = 1012.9(5) A³, and Z = 2. Both crystals comprise mixed stacks of donors and acceptors. The molecular geometry, the CO stretching frequencies, and the EPR spectra indicate that most of the component molecules in both crystals are in the neutral state. The electrical conductivity is, however, found to be high; especially the value for γDAP-BRL (10^-1 Ω^-1 cm^-1) is unusually high as a neutral mixed-stack complex.