In the title mononuclear complex, [Zn(N3)2(C8H8N6)2], the ZnII atom, lying on a twofold rotation axis, is six-coordinated in a distorted octa­hedral environment by four N atoms from two 2,4-diamino-6-(2-pyrid­yl)-1,3,5-triazine ligands and two N atoms from two end-on-coordinated azide ions. N—H⋯N hydrogen bonds between the ligand and azide ion link the complex mol­ecules into a three-dimensional network.

In the crystal of the title compound, C17H17N3O2, the mol­ecules exist in the keto–enamine form. The pyrazole ring is oriented at 10.59 (4) and 57.98 (5)° to the phenyl and furyl rings, respectively, and the dihedral angle between phenyl and furyl rings is 73.30 (11)°. An intra­molecular N—H⋯O hydrogen bond occurs between imino and carbonyl groups. In the crystal, weak C—H⋯O hydrogen bonds link the mol­ecules into supra­molecular chains along the b axis.

The title compound, [Eu(C12H9.33N2O)3]NO3, was obtained by the reaction of Eu(NO3)·3H2O and the Schiff base ligand 2-(2-pyridylimino­meth­yl)phenol. The Eu atom is located on a threefold rotation axis and is nine-coordinated by three tridentate Schiff base ligands in a distorted tricapped trigonal-prismatic geometry. The O atom at the phenol hydr­oxy group is partially deprotonated and the H atoms are modelled with one-third occupancy according to the space group R . Offset face-to-face π–π [centroid–centroid distance = 3.886 (3) Å] and edge-to-face C—H⋯π inter­actions are found between adjacent mol­ecules. An intra­molecular O—H⋯N hydrogen bond is also present.

In the title compound, C11H10ClN3S, the dihedral angle between the benzene and pyrimidine rings is 3.99 (4)°. In the crystal, inter­molecular N—H⋯N hydrogen bonds link the mol­ecules into ribbons of R 2 2(8) rings parallel to [100]. Weak C—H⋯S contacts connect adjacent ribbons into a two-dimensional undulating layer-like structure extending parallel to (110). The benzene and pyrimidine rings of adjacent mol­ecules have the offset face-to-face π–π stacking inter­actions in a zigzag fashion along the c axis, with perpendicular ring distances of 3.463 and 3.639 Å, and a dihedral angle between the planes of 3.99 (2)°. The distance between the ring centroids is 4.420 (2) Å.

The title complex, [Cu(C7H3NO4)(H2O)2]n, was prepared under hydro­thermal reaction conditions. In the crystal structure, the CuII cation is located on a twofold rotation axis and is coordinated by two carboxyl­ate O atoms and one N atom from three pyridine-3,5-dicarboxyl­ate (PDA) anions and two water mol­ecules with a distorted trigonal–bipyramidal geometry. The tridentate PDA anion is also located on the twofold rotation axis and bridges the CuII cations to form a two-dimensional polymeric layer. O—H⋯O hydrogen bonding between layers links the two-dimensional layers into a three-dimensional supra­molecular framework.