The molecular structures of 10,10'-biacridinyl-9,9'-dione (5), 9-(10'-
bromo-9'-anthryl)carbazole (9) and 9,9'-bicarbazyl (12) have been solv
ed by X-ray crystallography. Proton and carbon-13 NMR studies of these
and related compounds, show that in solution their conformations are
also 'scissor-like'. AM1 semi-empirical calculations provide a rationa
le for the geometries of these compounds.