Coordination complexes of zinc and manganese based on pyridine-2,5-dicarboxylic acid N-oxide: DFT studies and antiproliferative activities consideration

We report here the design, synthesis, and antiproliferative activity of three coordination complexes [Mn₂(pydco)₂(bpy)₂(H₂O)₂]·2H₂O (1), [Zn(bpy)(Hpydco)₂] (2), and [Zn(bpy)Cl(Hpydco)]·2H₂O (3) (H₂pydco = pyridine-2,5-dicarboxylic acid N-oxide, bpy = 2,2'-bipyridine). Molecular structures of these complexes have been characterized by elemental analysis, Fourier transform infrared spectroscopy, thermogravimetric analysis, and powder and single-crystal X-ray diffraction. According to the structural analysis, 1-3 are discrete complexes containing N- and O-donor ligands (bpy and pydco^2-) in which pydco^2- can be coordinated to the metal centres via the N-oxide oxygen and one carboxylate oxygen to generate a six-membered chelate ring. Also, these structures benefit from extensive intermolecular interactions such as hydrogen bonds and π-interactions which are the major forces to make them more stable in the solid state. The energetic features of the π-stacking interactions observed in compounds 1-3 have been computed and compared to the H-bonds. The interactions in the solid state have been also studied using the independent gradient model approach (IGM plot). The IGM-δg approach uses a new descriptor (δg) that locally represents the difference between a virtual upper limit of the electron density gradient and the true electron density gradient. This newly developed IGM methodology automatically extracts the signature of interactions between two given fragments. Finally, the antiproliferative properties of these complexes were tested on several cancer cell lines by MTT assay and flow cytometry. Also, to compare the antiproliferative activities of these complexes with common chemotherapy drugs, the antiproliferative property of cisplatin was evaluated as a reference and positive control.

A theoretical insight into the formation of chalcogen bonding (ChB) interactions involving coordinated DMSO molecules as σ-hole donors and benzoate groups as σ-hole acceptors in a dinuclear copper(ii) complex

The formation of two chalcogen bonding (ChB) interactions involving coordinated DMSO molecules as σ-hole donors and the O atoms of carboxylate groups as acceptors in a dimeric copper(ii) complex has been described.

Crystal and molecular structure of [Ni{2-H2NC(=O)C5H4N}2(H2O)2][Ni{2,6-(O2C)2C5H3N}2]·4.67H2O; DFT studies on hydrogen bonding energies in the crystal

[Ni{2-H₂NC(=O)C₅H₄N}₂(H₂O)₂][Ni{2,6-(O₂C)₂C₅H₃N}₂]·4.67H₂O, a new complex salt containing a bis(2,6-dicarboxypyridine)nickel(II) anion and a bis(2-amidopyridine)diaquanickel(II) cation, was synthesized and characterized. The crystal is stabilized by an extensive network of hydrogen bonds. Alternate layers of anions and cations/water molecules parallel to (010) can be distinguished. Computational studies of the network packing of the title compound by high-level DFT-D/B3LYP calculations indicate stabilization of the networks with conventional and non-conventional intermolecular O-H...O, N-H...O and C-H...O hydrogen bonds along with π-stacking contacts. Due to the presence of water molecules and the importance of forming hydrogen bonds with the involvement of water clusters to the stability of the crystal packing, the importance and role of these water clusters, and the quantitative stability resulting from the formation of hydrogen bonds and possibly other noncovalent bonds such as π-stacking are examined. The binding energies obtained by DFT-D calculations for these contacts indicate that hydrogen bonds, especially O-H...O and N-H...O, control the construction of the crystalline packing. Additionally, the results of Bader's theory of AIM for these interactions agree reasonably well with the calculated energies.

Influence of 2-Amino-4-methylpyridine and 2-Aminopyrimidine Ligands on the Malonic Acid-Cu(II) System: Insights through Supramolecular Interactions and Photoresponse Properties

Two Cu(II)-malonate complexes with 2-amino-4-methylpyridine (complex 1) and 2-aminopyrimidine (complex 2) auxiliary ligands were synthesized, and their single-crystal X-ray diffraction structures were established. Change in the auxiliary ligand exhibits substantial structural variation in the present complexes. Complex 1 shows a one-dimensional anionic copper-malonate moiety connected by the malonate bridge, whereas complex 2 is a mononuclear one. For both the complexes, auxiliary ligands are attached with the Cu-malonate moiety through various noncovalent interactions. Optical band gap, electrical conductivity, and photosensitivity of complexes 1 and 2 were measured, but the values of electrical parameters of the complexes significantly differ from each other. However, the magnitudes of electrical parameters increase several times for both the complexes when they are exposed under visible light, though the values of light sensing parameters of complex 1 were found to be higher than those of complex 2. Density functional theory calculations for complex 1 were carried out to support the experimental result.

Influence of noncovalent interactions on the structures of metal–organic hybrids based on a [VO2(2,6-pydc)]− tecton with cations of imidazole, pyridine and its derivatives

Hydrogen-bonding has a profound effect on topologies, and various 1D (band, pillar or chain), 2D and 3D hydrogen bonding networks have been observed.

On the importance of non covalent interactions in the structure of coordination Cu(ii) and Co(ii) complexes of pyrazine- and pyridine-dicarboxylic acid derivatives: experimental and theoretical views

We synthesized and X-ray characterized four complexes based on pyrazine- and pyridine-dicarboxylic acid ligands. One of them exhibited a relevant lp–π-hole interaction.