In the title compound, C(13)H(10)N(2)S, the dihedral angle between the imidazole and thio-phene rings is 16.89 (19)°, and the double bond adopts an E configuration. In the crystal structure, N-H⋯N hydrogen bonds link the mol-ecules into rows along b. There is also evidence of weak C-H⋯S inter-actions.

The symmetrical title compound, C(20)H(20)N(6)S(2), contains a disulfide bond of 2.0884 (6) Å. The C-S-S-C torsion angle is -59.57 (7)°. In the crystal, classical N-H⋯N and non-classical C-H⋯N hydrogen bonds link the compounds into chains along the a axis.

In the title compound, C(15)H(11)NO(4), the dihedral angle between the aromatic rings is 23.8 (2)° and an intra-molecular O-H⋯N hydrogen bond generates an S(6) ring. In the crystal, C-H⋯O hydrogen bonds link the mol-ecules into a three-dimensional network.

In the title compound, C(15)H(13)ClN(2)O(2), the dihedral angle between the two benzene rings is 7.0 (1)°. An intra-molecular N-H⋯O hydrogen bond is present and inter-molecular O-H⋯O hydrogen bonds link the mol-ecules into chains along [001].

The title Schiff base compound, C(14)H(9)Cl(3)N(2)O, exists in a trans configuration with respect to the C=N bond and the dihedral angle between the two benzene rings is 13.5 (2)°. In the crystal, inter-molecular N-H⋯O hydrogen bonds link adjacent mol-ecules into extended C(4) chains propagating along the c-axis direction.

The title compound, C(19)H(18)O(4), exhibits a long C-C bond [1.575 (2) Å] in the cage structure. In the crystal, pairs of O-H⋯O hydrogen bonds link the mol-ecules into centrosymmetric dimers. C-H⋯O inter-actions also occur.

In the title compound, C(17)H(16)BrNO(2), the two benzene rings make a dihedral angle of 7.4 (3)°; the hy-droxy group links to the carbonyl group via an intra-molecular O-H⋯O hydrogen bond. In the crystal, weak C-H⋯O inter-actions link the mol-ecules into a supra-molecular chain running along the c axis.

In the title compound, C18H18N2O4, the planes of the benzene rings are twisted with respect to each other at 27.25 (7)°. The mol-ecule displays an extended conformation with an intra-molecular O-H⋯N hydrogen bond. In the crystal, weak C-H⋯O inter-actions link the mol-ecules, forming supra-molecular chains running along the b-axis direction.

In the mol-ecule of the title compound, C(11)H(11)FN(2)O(4), the five-membered ring adopts an envelope conformation. An intra-molecular N-H⋯F hydrogen bond occurs. In the crystal structure, inter-molecular N-H⋯O hydrogen bonds link the mol-ecules.

The mol-ecular structure of the title compound, C(13)H(15)NO(3), is stabilized by a short intra-molecular O-H⋯O hydrogen bond within the maleamic unit. In the crystal, inter-molecular N-H⋯O hydrogen bonds link mol-ecules into zigzag chains propagating in [010].