In the title compound, C14H18N2O3, the carb­oxy­lic group is tilted by 12.00 (4)° with respect to the mean plane throught the benzimidazole ring system. The alcohol and carboxyl hydroxy groups are involved in intermolecular O—H⋯O and O—H⋯N hydrogen bonds, forming a two-dimensional network extending parallel the ab plane. The network is further stabilized by weak C—H⋯O inter­actions. The sec-butyl group is disordered over two sets of sites with refined occupancies of 0.484 (4) and 0.516 (4).

In the crystal structure of the title compound, C15H20N2O3S, the hy­droxy group is involved in the formation of O—H⋯N hydrogen bonds, which link two mol­ecules into a centrosymmetric dimer. Weak C—H⋯O hydrogen bonds further link these dimers into chains propagating along the a axis. The crystal packing exhibits π–π inter­actions between the five- and six-membered rings of neighbouring mol­ecules [centroid–centroid distance = 3.819 (2) Å] and short inter­molecular S⋯S contacts of 3.495 (1) Å.

In the title compound, C20H21BrN2O2, the bromo­phenyl ring is twisted by 40.13 (8)° from the benzimidazole mean plane and the Br atom deviates by 0.753 (1) Å from that plane. The sec-butyl group is disordered over two conformations in a 0.898 (5):0.102 (5) ratio. In the crystal, mol­ecules related by translation along [10] are linked into chains via weak C—H⋯Br hydrogen bonds.

In the title compound, C20H21FN2O2, the benzene ring and the benzimidazole ring system are inclined at a dihedral angle of 44.40 (9)°. In the crystal, mol­ecules are linked by inter­molecular C—H⋯O hydrogen bonds, forming a zigzag chain along the b-axis direction. An intra­molecular C—H⋯π inter­action is also observed.

In the title compound, C15H20N2O3, the benzimidazole ring is essentially planar, with a maximum deviation from the mean plane of 0.012 (1) Å. The crystal structure is stabilized by inter­molecular O—H⋯N hydrogen bonds, forming centrosymmetric dimers, which are connected in the [100] direction through weak C—H⋯O contacts.

In the title compound, C11H14N2O5, the mol­ecular structure is stabilized by an intra­molecular N—H⋯O hydrogen bond, which generates an S(6) ring motif. The nitro group is twisted slightly from the attached benzene ring, forming a dihedral angle of 5.2 (2)°. In the crystal packing, inter­molecular O—H⋯O and C—H⋯O hydrogen bonds link the mol­ecules into a three-dimensional network. The crystal studied was a non-merohedral twin, the refined ratio of the twin components being 0.264 (2):0.736 (2).

In the title mol­ecule, C20H22N2O2, the benzimidazole ring system is essentially planar, with a maximum deviation of 0.024 (1) Å. The dihedral angle between the phenyl and benzimidazole ring system is 43.71 (5)°. The atoms of the butyl group are disordered over two sets of sites with occupancies of 0.900 (4) and 0.100 (4). In the crystal structure, mol­ecules are connected by weak inter­molecular C—H⋯O hydrogen bonds, forming chains along the b axis. The crystal structure is further stabilized by C—H⋯π inter­actions.

In the title mol­ecule, C21H24N2O3, the imidazole ring is essentially planar, with a maxium deviation of 0.015 (1) Å. The dihedral angle between the benzene and imidazole rings is 65.47 (6)°. The crystal packing is stabilized by weak inter­molecular C—H⋯O and C—H⋯N hydrogen bonds, forming zigzag chains along the c axis. The crystal structure is further stabilized by C—H⋯π inter­actions.

In the crystal structure of the title compound, C13H18N2O4, the asymmetric unit consists of three crystallographically independent ethyl 4-butyl­amino-3-nitro­benzoate mol­ecules. There is an intra­molecular N—H⋯O hydrogen bond in each mol­ecule, which generates an S(6) ring motif. The structure is stabilized by inter­molecular N—H⋯O and C—H⋯O hydrogen bonds.

In the title compound, C11H14N2O4, all non-H atoms lie in a mirror plane except for one of the methyl groups which deviates from the mirror plane by 0.919 (3) Å and is twisted by a torsion angle of 62.9 (2)°. An intra­molecular N—H⋯O hydrogen bond generates an S(6) ring motif. In the crystal packing, the mol­ecules are linked together by O—H⋯O hydrogen bonds, forming dimers with graph-set motif R 2 2(8) which propagate along the a-axis direction. C—H⋯O contacts link adjacent dimers with a graph-set motif C 2 2(7), forming chains along b, and further consolidate the structure into a three-dimensional network. The crystal packing is further strengthened by short inter­molecular O⋯O=C [2.655 (4) Å] contacts.

In the title compound, C9H10N2O4, an intra­molecular N—H⋯O hydrogen-bond inter­action generates an S(6) ring motif. The nitro group is slightly twisted away from its attached benzene ring [dihedral angle = 15.29 (15)°]. In the crystal structure, mol­ecules are stacked down the a axis caused by short O⋯O(−1−x, −y, 2−z) contacts of 2.6481 (16) Å involving the O atoms of the nitro groups. The crystal packing is consolidated by inter­molecular O—H⋯O hydrogen bonds, linking the mol­ecules into centrosymmetric dimers.