Stacking interactions in the acridine dyes: spectrophotometric data and crystal structure of acridine orange hydroiodide and acridine orange hydrochloride monohydrate

The crystal structure of acridine orange hydroiodide and that of acridine orange hydrochloride monohydrate have been solved by X-ray diffraction analysis. The absorption spectra of both derivatives in the solid state have also been reported and compared with those of the acridinium ion in solution. The stacking interactions of the acridine orange molecule in both derivatives is discussed in the light of the visible absorption spectra in the solid state and in solution.