(E)-2-(4-Chloro­phen­oxy)-N′-(pyridin-4-yl­methyl­idene)acetohydrazide

In the title compound, C₁₄H₁₂ClN₃O₂, the acyl­hydrazone base [C(=O)—N—N=C] is essentially planar, with an r.m.s. deviation of 0.0095 Å, and makes a dihedral angle of 12.52 (10)°with the pyridine ring. In the crystal, molecules are linked via pairs of N—H...O hydrogen bonds, forming inversion dimers with an R₂²(8) graph-set motif. The dimers are linked via C—H...π interactions forming chains along [101].

4-Nitro­phenyl N-(2-sulfamoylphen­yl)carbamate

In the title mol­ecule, C₁₃H₁₁N₃O₆S, the dihedral angle between the benzene rings is 35.52 (8)°. An intra­molecular N—H...O hydrogen bond forms an S(6) ring. In the crystal, mol­ecules are linked via N—H...O hydrogen bonds into chains along [101] incorporating R₂²(8) and R₂²(16) rings.

1-(3-Carboxyl­atophen­yl)-4,4′-bipyridin-1-ium dihydrate

In the crystal structure of the title compound, C₁₇H₁₂N₂O₂·2H₂O, the carboxyl­ate group is linked via O—H...O hydrogen bonds to two water mol­ecules. The crystal packing is best described as parallel layers (viewed along the a axis) of viologen and water mol­ecules associated via O—H...O hydrogen bonds and π–π inter­actions, with a centroid–centroid separation of 3.8276 (9) Å.

Ethyl 3-(10-bromo­anthracen-9-yl)-5-methyl-1,2-oxazole-4-carboxyl­ate

In the title compound, C₂₁H₁₆BrNO₃, the mean planes of the anthracene tricycle and isoxazole ring are inclined to each other at a dihedral angle of 72.12 (7)°. The carb­oxy group is slightly out of the isoxazole mean plane, with a maximum deviation of 0.070 (5) Å for the carbonyl O atom. In the crystal, pairs of weak C—H...O hydrogen bonds link the mol­ecules into dimers, and weak C—H...N inter­actions further link these dimers into corrugated layers parallel to the bc plane.