Poly[[diaquabis{μ-4-[6-(4-carboxyphenyl)-4,4′-bipyridin-2-yl]benzoato-κ2 O:N 4′}zinc] dimethylformamide tetrasolvate]

In the title compound, {[Zn(C24H15N2O4)2(H2O)2]·4C3H7NO}n, the ZnII ion is located on an inversion center and is six-coordinated by two N atoms from two ligands, two carboxylate O atoms from two other symmetry-related ligands and two O atoms from two water molecules, furnishing a slightly distorted octahedral geometry. The ZnII atoms are connected by the bridging ligands into a layer parallel to (101). O—H⋯O hydrogen bonds link the layers and the dimethylformamide solvent molecules. π–π interactions between the pyridine and benzene rings [centroid–centroid distances = 3.7428 (17) and 3.7619 (17) Å] and intralayer O—H⋯O hydrogen bonds are also present.

In the title compound, {[Zn (C 24 H 15 N 2 O 4 ) 2 (H 2 O) 2 ]Á-4C 3 H 7 NO} n , the Zn II ion is located on an inversion center and is six-coordinated by two N atoms from two ligands, two carboxylate O atoms from two other symmetry-related ligands and two O atoms from two water molecules, furnishing a slightly distorted octahedral geometry. The Zn II atoms are connected by the bridging ligands into a layer parallel to (101). O-HÁ Á ÁO hydrogen bonds link the layers and the dimethylformamide solvent molecules.interactions between the pyridine and benzene rings [centroid-centroid distances = 3.7428 (17) and 3.7619 (17) Å ] and intralayer O-HÁ Á ÁO hydrogen bonds are also present.
The asymmetric unit of the title complex contains a half Zn II ion, one (bpydbH)ligand, one aqua ligand and two lattice dimethylformamide (DMF) molecules. As shown in Fig. 1, the Zn II ion, lying on an inversion center, is six-coordinated by two N atoms from two (bpydbH)ligands, two deprotonated carboxylate O atoms from the other two (bpydbH)ligands and two aqua ligands, furnishing a slightly distorted octahedral geometry. The bond distances and angles are in the normal range (Song et al., 2012). The Zn nodes are extended by the (bpydbH)linkers in four directions, forming a layer parallel to (101) (Fig. 2). Intralayer O-H···O hydrogen bonds stabilize the layer. O-H···O hydrogen bonds link the layers and the dimethylformamide solvent molecules. π-π interactions between the pyridine and benzene rings [centroidcentroid distances = 3.7428 (17) and 3.7619 (17) Å] are also present.
After it was cooled to room temperature slowly, colorless crystals were collected by filtration, washed with DMF and dried in air, with a yield of 59% based on bpydbH 2 .

Refinement
H atoms on C atoms were positioned geometrically and refined as riding atoms, with C-H = 0.93 (aromatic) and 0.96 (CH 3 ) Å and with U iso (H) = 1.2(1.5 for methyl)U eq (C). H atoms bonded to O atoms were located in a difference Fourier map and refined with distance restraints of O-H = 0.85 (1) Å and with U iso (H) = 1.5U eq (O).  The asymmetric unit of the title compound. Displacement ellipsoids are drawn at the 50% probability level. [Symmetry

Figure 2
View of the layer structure in the title compound.

Poly[[diaquabis{µ-4-[6-(4-carboxyphenyl)-4,4′-bipyridin-2-yl]benzoato-
Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > 2sigma(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.