Molecular complexes of CI disperse yellow 211 with aromatic compounds

Abstract

This paper describes some anomalous behaviour of the disperse monoazo dyestuff CI Disperse Yellow 211 which is able to form molecular complexes of the CT (Charge Transfer) type with various aromatic compounds. The complexes are formed in the solid phase. They are separated as crystalline substances of orange, red, ruby to blue-violet colour, whereas in organic solvents they are practically fully dissociated into the starting components. The complexes were isolated from an aqueous dyebath and recrystallized from organic solvents. Their composition, structure and properties were determined by elemental analysis, X-ray diffraction, spectrophotometry and liquid chromatography. From the crystal and molecular structure determinations, it was concluded that the crystals of the molecular complexes are stabilized by van der Waals forces and, partially, by the π-π interaction of the aromatic nuclei of the dye with those of the respective aromatic compound. The so far unpublished constitution of CI Disperse Yellow 211 has been determined and confirmed by independent synthesis.