Fig. 2From: The synthesis characterization of historical novel azo pigments: implications for conservation scienceStructure of historical arylides synthesized: PY49: R1 = –CH3, R3 = R7 = –Cl, R5 = R8 = –OCH3; PY98: R1 = –NO2 R3 = R7 = –Cl, R5 = –CH3; PY203: R1 = –NO2, R4 = –CH3, R5 = –OCH3Back to article page