Crystal structure of (E)-4-{2-[4-(all-yloxy)phen-yl]diazen-yl}benzoic acid

The title compound, C16H14N2O3, has an E conformation about the azo-benzene [-N=N- = 1.2481 (16) Å] linkage. The benzene rings are almost coplanar [dihedral angle = 1.36 (7)°]. The O atoms of the carb-oxy-lic acid group are disordered over two sets of sites and were refined with an occupancy ratio of 0.5:0.5. The two disordered components of the carb-oxy-lic acid group make dihedral angles of 1.5 (14) and 3.8 (12)° with the benzene ring to which they are attached. In the crystal, mol-ecules are linked via pairs of O-H⋯O hydrogen bonds, forming inversion dimers. The dimers are connected via C-H⋯O hydrogen bonds, forming ribbons lying parallel to [120]. These ribbons are linked via C-H⋯π inter-actions, forming slabs parallel to (001).