Controlling the Conductivity of Oligomer Radical Cations by Tuning Stacking Structures of π‑Dimers

Salts containing radical cations of dialkoxyterphenyls (DP) including 4,4′-dimethoxyterphenyl (1) and 4,4′-diethoxyterphenyl (2) have been isolated with weakly coordinating anions [Al­(OR_F)₄]⁻ (OR_F = OC­(CF₃)₃) or [Al­(OR_Me)₄]⁻ (OR_Me = OC­(CF₃)₂CH₃) as the counterions. The radical cation salts have been characterized by single-crystal X-ray diffraction analysis, UV–vis absorption, and electron paramagnetic resonance spectroscopy, as well as conductivity measurements. Single-crystal structures indicate that the radical cations assemble into infinite stacks of π-dimer in these salts, while single-crystal conductivity measurements show that the conductivity of the salts is significantly affected by substituent groups and the interaction among the cation, anion, and solvent.