1H-Benzotriazol-1-yl 4-{(E)-[4-(dimethyl­amino)­phen­yl]diazen­yl}benzoate

The title compound, C(21)H(18)N(6)O(2), was obtained as a by-product of a reaction between (E)-4-(4-dimethyl­amino­phenyl­azo)benzoic acid and 2-amino-4-(2-pyrid­yl)-6-(6-pyrid­yl)-1,3,5-triazine, which has a very low solubility, under peptidic coupling conditions, using THF as solvent. The condensation reaction occurred between 1-hy­droxy­benzotriazole and (E)-4-(4-dimethyl­amino­phenyl­azo)benzoic acid. The dihedral angle between the benzene rings in the (E)-diphenyl­diazene fragment is 10.92 (13)° and that between the benzotriazole mean plane and the central benzene ring is 80.57 (7)°. In the crystal, π–π stacking [centroid–centroid distances = 3.823 (2) and 3.863 (2) Å] of similar fragments generates mol­ecular layers parallel to (0-12). The crystal packing also features weak C—H⋯N hydrogen bonds involving N atoms of the benzotriazole ring.