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The reaction of copper (II) nitrate with pyridine-2,6-dicarboxylic acid, (pydcH₂) and 2,2'-bipyridine (2,2'-bipy) led to the formation of the title compound, [Cu(C₇H₄NO₄)(C₁₀H₈N₂)(H₂O)]NO₃.H₂O, or [Cu(pydcH)(2,2'-bipy)(H₂O)]NO₃.H₂O. The crystal system of the complex is triclinic with space group P and two molecules per unit cell. The unit cell parameters are: a = 7.0438 (6) Å, b = 11.3215 (10) Å, c = 12.9148 (9) Å, α = 107.498 (4)°, β = 94.557 (5)° and  g = 104.325 (5)°. The final R value was 0.03 for 3601 observed reflections. The cationic complex features six-coordinate Cu^II with a distorted octahedral geometry with a significantly longer Cu1—O4 bond [2.5491(16) Å]. Considerable C═O···π stacking interactions between the C═O groups with distance of 3.498 (2) Å are observed. In addition, distinct intermolecular O—H···O and N—H···O hydrogen bonds lead to the formation of R(12) and C(12) graph sets motifs. In the crystal structure, a wide range of non-covalent interactions consisting of hydrogen bonding (O—H···O, O—H···N and C—H···O), π–π [centroid–centroid distances of 3.5193 (13) Å and 3.6876 (13) Å] and C═O···π stacking interactions connect the various components into a supramolecular structure.

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The compound of (Htmb)₂[Ni(pydc)­₂)].H₂O (1) (In that tmb and pydc are 3,3¢,5,5¢-tetramethyl benzidine and pyridine -2,6- dicarboxylic acid, respectively) was synthesized via the proton transfer method and the structure was determined by single crystal X-ray diffraction. This compound crystalized in monoclinic crystal system and C2/c space group. In the asymmetry unit of compound 1, there are half molecule of the [Ni(pydc)­₂)]^2- anionic complex, one protonated molecule of 3,3¢,5,5¢-tetramethyl benzidine as a counter ion and half of an uncoordinated water molecule. Extensive intermolecular N-H…O and O-H…N, hydrogen bonds along with π… π and C-H …π interactions contribute in self-assembly and formation of a novel supramolecular structure.