8-[(3-Phenyl-1,2,4-oxa-diazol-5-yl)meth-oxy]quinoline monohydrate.

In the title compound, C18H13N3O2·H2O, the oxa-diazole ring forms dihedral angles 7.21 (10) and 21.25 (11)° with the quinoline and benzene rings, respectively. The crystal structure features O-H⋯N hydrogen bonds and is further consolidated by C-H⋯O hydrogen-bonding inter-actions involving the water molecule of hydration.

8-{[3-(3-Meth-oxy-phen-yl)-1,2,4-oxa-diazol-5-yl]meth-oxy}quinoline monohydrate.

In the title hydrate, C19H15N3O3·H2O, the three aromatic groups in the quinoline derivative are close to coplanar: the central oxa-diazole fragment makes dihedral angles of 15.7 (2)° with the benzene ring and 5.30 (14)° with the quinoline ring system. In the crystal, the organic mol-ecules are connected with water mol-ecules by pairs of O-H⋯N hydrogen bonds involving the quinoline and oxa-diazole N atoms. The mol-ecules form stacks along the a axis, neighboring mol-ecules within each stack being related by inversion and the shortest distance between the centroids of the oxa-diazole and pyridine rings being 3.500 (2) Å. Mol-ecules from neighboring stacks are linked by weak C-H⋯O hydrogen bonds, forming a three-dimensional structure.

5-Nitro-1-benzofuran-2(3H)-one.

In the crystal structure of the title compound, C(8)H(5)NO(4), essentially planar mol-ecules [largest deviation from the least-squares plane = 0.030 (2) Å] form stacks along the a-axis direction. Intercentroid separations between overlapping benzene rings within the stack are 3.6594 (12) Šand 3.8131 (12) Å. Mol-ecules from neighboring stacks are linked by weak C-H⋯O hydrogen bonds into inversion dimers.