Adipato bridged novel hexanuclear Cu(ii) and polymeric Co(ii) coordination compounds involving cooperative supramolecular assemblies and encapsulated guest water clusters in a square grid host: antiproliferative evaluation and theoretical studies.

Two new coordination compounds involving hexanuclear Cu(ii), viz., [Cu6(phen)6(µ4-adpt)4(H2O)2](NO3)4·10H2O (1) and polymeric Co(ii), viz., {[(µ2-adpt)4Co(µ2-H2O)2Co(H2O)4]·4H2O}n (2) (phen = 1,10-phenanthroline; adpt = adipate) have been synthesized and characterized using elemental analysis, TGA, spectroscopic (IR, electronic and ESR), PXRD and single crystal X-ray diffraction techniques. Discrete nitrate-water clusters involving the [(H2O)3NO3]- core in 1 and linear (H2O)4 core in 2 provide stability to the layered network of the structures of the compounds. Interestingly, the water clusters in polymer 2 are encapsulated as guests in the voids of the host square grid that extends in 2D architecture. Theoretical studies have revealed the presence of interesting energetically significant cooperativity effects of π-stacking contacts that are responsible for the hexanuclear structure of compound 1. Both complexes significantly inhibit cell viability by inducing apoptotic cell death in the DL cancer cell line with negligible cytotoxicity in normal cells (PBMC). An assessment of ROS (reactive oxygen species) level study revealed a rapid increase of ROS in DL cells indicating cytotoxicity of the compounds against the DL cells. A decrease in MMP (mitochondrial membrane potential) is associated with an opening of the mitochondrial permeability transition pores which corroborates the apoptotic features of 1 and 2. The mode of action of the cytotoxic activities of the compounds has been explored with respect to their in silico docking ability and further inhibition of antiapoptotic proteins as evidenced by western blot analysis. SAR analyses based on pharmacophore modelling reveal that the molecular features of the structures of the compounds play important roles in biological activities.

Antiproliferative evaluation and supramolecular association in Mn(II) and Zn(II) bipyridine complexes: Combined experimental and theoretical studies.

Two new coordination complexes viz. [Mn2(µ­O,O'­4­Mebz)2(bpy)2(µ2­H2O)(4­Mebz)2] (1) and [Zn(bpy)(pdc)(H2O)]·3.5H2O (2) (where bpy = 2,2'­bipyridine, 4­Mebz = 4­methyl benzoate and pdc = 2,6­pyridine dicarboxylate) were synthesized and structurally characterized by single crystal X-ray diffraction, FT-IR, electronic spectroscopy, Thermogravimetric Analysis (TGA) and Powder X-ray diffraction (PXRD) techniques. Complex 1 consists of a dinuclear Mn(II) unit bridged by a solvent water molecule while 2 is a mononuclear complex. The supramolecular assemblies found in the solid state of both complexes have been described. In 2, several π-stacking interactions modes have been further studied using Density Functional Theory (DFT) calculations. Furthermore, the activity of the complexes against a few pathogenic bacteria has been studied and confirmed. Finally, the antiproliferative activities of both complexes have been studied in T-cell lymphoma cell line by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, apoptosis assay and molecular docking simulation. Both the complexes exhibit gratifying cytotoxicity through apoptotic cell death with negligible cytotoxicity (~5-10%) in normal cells. It is worth mentioning that Mn(II) and Zn(II) complexes exhibit interaction modes with highly expressed cancer target proteins under study with higher binding affinity and the results are comparable with reference inhibitors.

Solvent-driven structural topology involving energetically significant intra- and intermolecular chelate ring contacts and anticancer activities of Cu(ii) phenanthroline complexes involving benzoates: experimental and theoretical studies.

Two new coordination solids [Cu2(µ2-Bz)4(CH3OH)2][Cu2(η2-Bz)2(phen)2(H2O)2]·(NO3)2 (1) and [Cu(phen)(H2O)(Bz)(η2-Bz)] (2) (phen = 1,10-phenanthroline; Bz = benzoate) have been synthesized and characterized using elemental analysis, TGA, spectroscopic (IR, UV-vis-NIR and ESR) and single crystal X-ray diffraction techniques. Change of the solvent from methanol to DMF results in changes in the architectures that are triggered by a change from square pyramidal to octahedral coordination at the divalent metal centers for complexes 1 and 2 respectively. The structural topology of the complexes is established by the interplay of strong O-H⋯O and weak C-H⋯O, C-H⋯C, π-π stacking interactions. Unconventional parallel intramolecular and anti-parallel intermolecular contacts involving the chelate rings (CR) also stabilize the structures. The energetic analyses of the structures evidence that the parallel arrangement is energetically favoured which is likely due to the presence of the Cu⋯Cu cuprophilic interaction in 1 that is not established in 2. Compound 1 exhibits the highest antibacterial activity against Rhizobium leguminosarum among the tested cultures. In vitro cytotoxicity and apoptosis studies were carried out for compounds 1 and 2 on malignant Dalton's lymphoma cell line (DL). Both compounds showed a significant effect on the decrease in cell viability as compared to a control, while compound 2 induced remarkable cytotoxicity towards DL cells. Treatment also showed the appearance of membrane blebbing, chromatin condensation and fragmented nuclei which are typical characteristic features of apoptotic cell death. Furthermore, a docking study revealed that both compounds docked in the active sites of all the cancer target proteins under study. Moreover, SAR analysis revealed that oxygen and nitrogen atoms of compound 1 and the oxygen atoms of compound 2 are crucial for biological activities.

Inverse bilayer structure of mononuclear Co(II) and Ni(II) complexes of the type M(H2O)3(SO4)(4-CNpy)2.

Two new metal compounds of the formula [M(H(2)O)(3)(SO(4))(4-CNpy)(2)] x H(2)O [M = Ni (1) and Co (2), 4-CNpy = 4-cyanopyridine] have been prepared and studied by X-ray diffraction. In both of these compounds the 4-CNpy ligands are coordinated via pyridyl-N atoms to the metal ions in a cis fashion. The neutral complexes along with the uncoordinated H(2)O molecules are glued together preferentially into inverse bilayers by non-covalent interactions, including unique interlayer pi-pi interactions between antiparallel nitrile groups. Hartree-Fock and density-functional theory (DFT) calculations indicate that the pi-pi interactions are energetically significant. The unit-cell similarity index (Pi) of 0.0046 for the compounds suggests their isostructurality, which is also supported by their X-ray powder diffraction patterns that can be almost superimposed.