In the title compound, C26H24N2O2, the benzimidazole ring system is almost planar [maximum displacement = 0.025 (1) Å] and makes dihedral angles of 80.48 (5) and 41.57 (5)° with the benzene rings, which are inclined to one another by 65.33 (6)°. In the crystal, mol­ecules are linked via C—H⋯π and weak π–π inter­actions [centroid–centroid distance = 3.8070 (7) Å and inter­planar distance = 3.6160 (5) Å].

The title compound, C17H16N2O3, has an E conformation about the azobenzene (–N=N–) linkage. The benzene rings are twisted slightly with respect to each other [6.79 (9)°], while the dihedral angle between the plane through the carb­oxy group and the attached benzene ring is 3.2 (2)°. In the crystal, mol­ecules are oriented with the carb­oxy groups head-to-head, forming O—H⋯O hydrogen-bonded inversion dimers. These dimers are connected by C—H⋯O hydrogen-bonds into layers lying parallel to the (013) plane.

In the title compound, C20H22BrN5O2·2H2O, the Schiff base mol­ecule exists in an E conformation with respect to the acyclic C=N bond. An S(6) ring motif is formed via an intra­molecular O—H⋯N hydrogen bond. The dihedral angle between the imidazo[1,2-a]pyridine system and the benzene ring is 84.62 (5)°. In the crystal, N—H⋯O, O—H⋯O, O—H⋯N, C—H⋯O and C—H⋯Br hydrogen bonds link the mol­ecules into a three-dimensional network. The crystal packing is further stabilized by C—H⋯π and π–π inter­actions [centroid–centroid distance = 3.5365 (7) Å].

In the title compound, C20H14Cl2F3NO3, the trifluromethyl group is disordered over two sets of sites in a 0.784 (10):0.216 (10) ratio. The quinoline ring system is essentially planar with a maximum deviation of 0.058 (2) Å for the N atom and forms dihedral angles of 89.23 (11) and 8.13 (17)°, respectively with the mean planes of the benzene ring and the carboxyl­ate group. In the crystal, pairs of weak C—H⋯O and C—H⋯F hydrogen bonds link mol­ecules into centrosymmetric dimers. The crystal structure is further stabilized by weak π–π [centroid–centroid distance = 3.624 (2) Å] inter­actions.