The first entangled metal-ppa complex, containing unique 5-fold interlocking tri-flexure helices and 15-fold interwoven helices, defines an unprecedented 3-fold interpenetrated double-edged pseudo-diamondoid (pseudo-dia) network, which, not only represents the first and only example of interpenetrating metal-quinolone complex, but also represents the highest degree of interpenetration presently known for double-edged nets.

The asymmetric unit of the title compound, 2C14H18N5O3 +·C10H5O8 2−·8H2O, contains one [H2ppa]+cation, one half of an [H2btec]2− anion (H4btec = 1,2,4,5-benzene­tetra­carb­oxy­lic acid and Hppa = 8-ethyl-5-oxo-2-piperazin-1-yl-5,8-dihydro­pyrido[2,3-d]pyrimidine-6-carb­oxy­lic acid) that is completed by inversion symmetry and four water mol­ecules. In the crystal, the mol­ecules are connected by inter­molecular hydrogen-bonding inter­actions and π–π stacking between the benzene rings of the [H2btec]2− anion and the pyrimidine rings of the [H2ppa]+ cation [centroid–centroid distance = 3.597 (3) Å], generating a three-dimensional supra­molecular structure.

In the title compound, [Zn(C14H17N5O3)(C9H4O6)(H2O)2]·H2O, the complex mol­ecule exists in a zwitterionic form. The ZnII ion exhibits a distorted tetra­gonal-pyramidal geometry, being coordinated by two O atoms from the zwitterionic 8-ethyl-5-oxo-2-(piperazin-4-ium-1-yl)-5,8-dihydro­pyrido[2,3-d]pyrimidine-6-carboxyl­ate (L) ligand, one O atom from the 5-carb­oxy­benzene-1,3-dicarboxyl­ate dianion, [Hbtc]2−, and two O atoms from two aqua ligands. In the crystal, N—H⋯O and O—H⋯O hydrogen bonds link the components into a three-dimensional structure. The crystal packing exhibits π–π inter­actions between the aromatic rings, with centroid–centroid distances in the range 3.466 (3)–3.667 (3) Å.

In the title complex, [Cu(NO3)2(C17H18FN3O3)2], the CuII ion is located on an inversion center. It exhibits a distorted octa­hedral geometry, being coordinated by six O atoms, four from two ciprofloxacin ligand mol­ecules (L), which act as bidentate ligands, and two from two nitrate anions. In the ligand, the piperazine ring has a chair conformation and the quinoline system is essentially planar [maximum deviation = 0.097 (2) Å]. One of the nitrate O atoms is disordered over two positions [occupancy ratio = 0.51 (6):0.49 (6)]. There is a C—H⋯F inter­action in the complex. In the crystal, mol­ecules are linked via N—H⋯O hydrogen bonds generating a two-dimensional network lying parallel to (111). The presence of C—H⋯O inter­actions leads to the formation of a three-dimensional structure. The title complex was prepared by hydro­thermal synthesis, and the hexa­hydrate form of this complex, synthesized by conventional methods, has been reported previously [Hernandez-Gil et al. (2009 ▶). Polyhedron, 28, 138–144].

In the crystal of title compound, C16H19FN3O+·C10H5O8 −·H2O, the water mol­ecule and the ions are connected by inter­molecular N—H⋯O and O—H⋯O hydrogen bonds and π–π stacking [centroid–centroid separation = 3.602 (1) Å] between the benzene ring and the pyridine ring, generating a three-dimensional supra­molecular structure.