Organic binary charge-transfer compounds of 2,2' : 6',2'' : 6'',6-trioxotriphenylamine and a pyrene-annulated azaacene as donors.

Three binary charge-transfer (CT) compounds resulting from the donor 2,2' : 6',2'' : 6'',6-trioxotriphenylamine (TOTA) and the acceptors FTCNQ and FBQ and of a pyrene-annulated azaacene (PAA) with the acceptor FTCNQ are reported. The identity of these CT compounds are confirmed by single-crystal X-ray diffraction as well as by IR, UV-vis-NIR and EPR spectroscopy. X-ray diffraction analysis reveals a 1 : 1 stoichiometry for TOTA·FTCNQ, a 2 : 1 donor : acceptor ratio in (TOTA)·FBQ, and a rare 4 : 1 stoichiometry in (PAA)·FTCNQ, respectively. Metrical parameters of the donor (D) and acceptor (A) constituents as well as IR spectra indicate full CT in TOTA·FTCNQ, partial CT in (TOTA)·FBQ and only a very modest one in (PAA)·FTCNQ. Intricate packing motifs are present in the crystal lattice with encaged, π-stacked (FTCNQ) dimers in TOTA·FTCNQ or mixed D/A stacks in the other two compounds. Their solid-state UV-vis-NIR spectra feature CT transitions. The CT compounds with FTCNQ are electrical insulators, while (TOTA)·FBQ is weakly conducting.