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In the crystal structure of the title compound, C6H7N·CH4N2O, the 2-methyl­pyridine and urea mol­ecules are linked via N—H⋯O and N—H⋯N hydrogen bonds, forming ribbons extending along the a axis. The dihedral angle between the 2-methyl­pyridine and urea mean planes is 89.09 (9)°. The methyl group shows rotational disorder wherein the H atoms are located over two sets of sites with equal occupancies.

During an attempt to prepare a cocrystal of N-phenyl­phthalimide, C14H9NO2, with N-(2,3,4,5,6-penta­fluoro­phen­yl)phthalimide, a new ortho­rhom­bic polymorph of the first component was obtained. This new form has Z′ = 0.5 and the mol­ecule is located around a twofold axis, whereas in the previously reported polymorph (space group Pbca), the mol­ecule has no crystallographically imposed symmetry. Pairs of C—H⋯O inter­actions between inversion-related phthalimide units arrange mol­ecules into tapes that are further assembled into (010) layers via stacking inter­actions between phthalimide fragments [inter­planar distance = 3.37 (5) Å].

The six different crystals of the versatile clathrate host racemic 1,1‘-binaphthyl-2,2‘-dicarboxylic acid (BNDA) that are obtained from its solution in 1,4-dioxane at varying crystallization temperatures from 15 to 35 °C are reported. They involve four solvates (1, 2BNDA/dioxane; 2, BNDA/dioxane; 3, 2BNDA/2dioxane; 4, BNDA/2dioxane), one mixed 1,4-dioxane solvate with water (5, BNDA/3dioxane/H3O+), and one guest-free form. The framework structures are characterized by 0D associates (1, 3, and 4) that either include (3, 4) or don't include (1) guest molecules and by 1D zigzag chains with (5) or without (2) participation of guest molecules. The pseudotetramorphic solvates 1−4 are formed in accordance with a previously formulated rule for pseudopolymorphic clathrates, which is as follows:  (i) the guest:host ratio decreases as the crystallization temperature increases, and (ii) the higher the formation temperature of the clathrate modification, the closer the space occupied by guest molecules.

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The ZnII ion in the title compound, [Zn(C9H6NO4)2(H2O)4], is located on an inversion center and is octahedrally coordinated by two 2-(2-oxo-2,3-dihydro-1,3-benzoxazol-3-yl)acetate anions in axial sites and four water molecules in equatorial positions. In the crystal, O—H...O hydrogen bonds between the coordinated water molecules and carbonyl–carboxylate O atoms lead to pleated sheets parallel to (001)

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