Crystal structures of C.I. Disperse Red 65 and C.I. Disperse Red 73

Single crystals of C.I. Disperse Red 65 and C.I. Disperse Red 73 were grown from ethyl acetate and acetonitrile/toluene solutions, respectively, and their crystal structures were determined using single-crystal X-ray diffraction analysis. In each dye molecule, the aminoazobenzene framework is almost planar due to intramolecular H-bonding. In the case of C.I. Disperse Red 65, intermolecular associations occur by π–π stacking and intermolecular H-bonding, resulting in a herringbone-type arrangement; for C.I. Disperse Red 73, toluene molecules stabilize the crystal structure via π–π stacking.