Crystal structures of 2,7-dinitro-9,10-anthraquinone, 1,8-dinitro-9,10-anthraquinone, and their anthracene complexes

Abstract

Abstract The molecular structures of 2,7-dinitro-9,10-anthraquinone (2,7-DNAQ), 1,8-dinitro-9,10-anthraquinone (1,8-DNAQ), and those of their π-complexes with anthracene have been investigated by X-ray diffraction. In 2,7-DNAQ, the two nitro groups are in conrotatory fashion twisted out of the aromatic ring planes by 13.6° and 12.5°, respectively. The crystalline complex of 2,7-DNAQ with anthracene is characterized by stacking of alternating donor and acceptor molecules, which are separated by 3.4 Å. The nitro groups of 1,8-DNAQ are twisted in disrotatory fashion out of the planes of the lateral rings by 63.5° and 70.4°, respectively. Anthracene and 1,8-DNAQ form a 1:2 complex in which the π-electron donor molecule is sandwiched between two head-to-tail oriented acceptor molecules.