Evaluation of central-metal effect on anticancer activity and mechanism of action of isostructural Cu(II) and Ni(II) complexes containing pyridine-2,6-dicarboxylate.

Two Cu(II) (C1) and Ni(II) (C2) complexes were designed through the one-pot reaction of pyridine-2,6-dicarboxylic acid and 2-aminobenzimidazole respectively with copper(II) nitrate hexahydrate and nickel(II) nitrate hexahydrate. Both complexes were characterized by single-crystal X-ray diffraction and the distorted octahedral geometry was recognized for them. The MTT assay indicated that the complexes have a significant antiproliferative effect on BEL-7404 cells. IC50 values confirmed that C1 (IC50 = 0.56 µM) is several times more potent than C2 (IC50 = 5.13 µM). The similar cellular uptake of the complexes in mentioned cells led to this proposal that the production of ROS with different values can be the main reason for different cytotoxicity of the complexes. In this study, C1 and C2 caused BEL-7404 cells arrest at the G2/M and S phases, respectively. The expression of p53, Bax up-regulation, and Bcl-2 down-regulation and also activation of procaspase-9, and 3 indicated that apoptosis through a caspase-dependent mitochondrion pathway is a remarkable pathway in BEL-7404 cells treated by C1 while mechanistic studies proved that C2 induce death of BEL-7404 cells through the activation of RAGE/PI3KC3/Beclin 1 autophagic cell signaling pathway, more specifically. The cytostatic effect of the complexes in the BEL-7404 3D spheroid model was depicted.

Novel Tl(III) complexes containing pyridine-2,6-dicarboxylate derivatives with selective anticancer activity through inducing mitochondria-mediated apoptosis in A375 cells.

Three novel Tl(III) complexes (C1), (C2) and (C3) were synthesized using the one-pot reactions of pyridine dicarboxylic acid derivatives, 2-aminobenzimidazole and/or 4-aminopyridine, and also thallium(III) nitrate trihydrate metal salt. The structure of all three complexes was determined by the single-crystal X-ray diffraction. C1 and C2 were realized to be isostructural with disordered square anti-prismatic geometry and for C3 arrangement of the distorted tricapped triangular prism was proposed. Cyclic voltammetry measurements on the complexes exhibited that formal potential values are more positive for C1 (E0' 0.109 V) and C3 (E0' 0.244 V) compared to C2 (E0' -0.051 V), versus Ag/AgCl under argon. Moreover, cytotoxicity of the compounds was evaluated in vitro against two cancer cell lines including a human melanoma (A375), a human colon adenocarcinoma (HT29), and also one normal cell human foreskin fibroblast (HFF). The selective and potent cytotoxicity effect was exhibited by C1 and C3 on cancer cell lines. The apoptosis through a caspase-dependent mitochondrion pathway was confirmed by ROS production, MMP reduction, p53 activation, Bax up-regulation, and Bcl-2 down-regulation, cytochrome c release, procaspase-9, and 3 expression, for A375 cells treated to C1 and C3. According to similar cellular uptake of the complexes in A375 cell line, the generation of ROS was considered as an effective agent to justify the inhibition effect C1 and C3 on mentioned cells. Furthermore, arresting the cell cycle in the G2-M phase and inducing apoptosis were indicated by these two complexes.

A nickel nanoparticle engineered CoFe2O4/SiO2-NH2@carboxamide composite as a novel scaffold for the oxidation of sulfides and oxidative coupling of thiols.

The purpose of this work was to prepare a new Ni-carboxamide complex supported on CoFe2O4 nanoparticles (CoFe2O4/SiO2-NH2@carboxamide-Ni). The carboxamide host material unit generated cavities that stabilized the nickel nanoparticles effectively and prevented the aggregation and separation of these particles on the surface. This compound was appropriately characterized using FT-IR spectroscopy, FE-SEM, ICP-OES, EDX, XRD, TGA analysis, VSM, and X-ray atomic mapping. The catalytic oxidation of sulfides and oxidative coupling of thiols in the presence of the designed catalyst was explored as a highly selective catalyst using hydrogen peroxide (H2O2) as a green oxidant. The easy separation, simple workup, excellent stability of the nanocatalyst, short reaction times, non-explosive materials as well as appropriate yields of the products are some outstanding advantages of this protocol.

Immobilized VO-Schiff Base Complex on Modified Graphene Oxide Nanosheets as an Efficient and Recyclable Heterogeneous Catalyst in Deep Desulfurization of Model Oil.

New heterogeneous catalyst was synthesized via covalent anchoring of oxovanadium(IV) complex of 5,5?-dibromobis(salicyledene)diethylenetriamine (VO[5-Br(Saldien)]) on the surface of chloro-modified graphene oxide (GO@CTS). The structure of the catalyst was investigated using different characterization techniques such as XRD, SEM, EDX, FT-IR, TG, DTA and ICP-AES analyses. The synthesized heterogeneous oxovanadium(IV) was an efficient catalyst for high yield and selective oxidation desulfurization (ODS) of dibenzothiophene (DBT) as a model oil using H2O2 as oxidant and formic acid as a promoter. The effects of the catalyst mass, reaction temperature and time, formic acid/H2O2 ratio and molar ratio of H2O2 to the total amount of sulfur (O/S) on oxidation desulfurization activity were investigated. Moreover, the prepared catalyst can be easily separated from the reaction mixture and reused six times without a significant loss of catalytic activity and selectivity.

A nickel nanoparticle engineered CoFe2O4@GO-Kryptofix 22 composite: a green and retrievable catalytic system for the synthesis of 1,4-benzodiazepines in water.

A composite of Ni nanoparticles incorporated in Kryptofix 22 conjugated magnetic nano-graphene oxide, CoFe2O4@GO-K 22·Ni, was synthesized via the grafting of Kryptofix 22 moieties on the magnetic nano-graphene oxide surface, followed by reaction of the nanocomposite with nickel nitrate. The Kryptofix 22 host material unit cavities can stabilize the Ni nanoparticles effectively and prevent their aggregation and separation from the surface. Characterization of the catalysts by FT-IR, FE-SEM, TGA, ICP, EDX, XRD, VSM and BET aided understanding the catalyst structure and morphology. This catalyst was efficiently applied for the synthesis of 1,4-benzodiazepine derivatives. The main advantages of the method are mild reaction conditions, inexpensive catalyst, it is environmentally benign, has high to excellent yields and shorter reaction times. This organometallic catalyst can be easily separated from a reaction mixture and was successfully examined for six runs with a slight loss of catalytic activity.

Hexaaqua-nickel(II) tetra-aqua-bis-(µ-pyridine-2,6-dicarboxyl-ato)bis-(pyridine-2,6-dicarboxyl-ato)trinickelate(II) octa-hydrate.

The title compound, [Ni(H(2)O)(6)][Ni(3)(C(7)H(3)NO(4))(4)(H(2)O)(4)]·8H(2)O, was obtained by the reaction of nickel(II) nitrate hexa-hydrate with pyridine-2,6-dicarb-oxy-lic acid (pydcH(2)) and 1,10-phenanothroline (phen) in an aqueous solution. The latter ligand is not involved in formation of the title complex. There are three different Ni(II) atoms in the asymmetric unit, two of which are located on inversion centers, and thus the [Ni(H(2)O)(6)](2+) cation and the trinuclear {[Ni(pydc)(2)](2)-µ-Ni(H(2)O)(4)}(2-) anion are centrosymmetric. All Ni(II) atoms exhibit an octa-hedral coordination geometry. Various inter-actions, including numerous O-H⋯O and C-H⋯O hydrogen bonds and C-O⋯π stacking of the pyridine and carboxyl-ate groups [3.570 (1), 3.758 (1) and 3.609 (1) Å], are observed in the crystal structure.

catena-Poly[[triaqua-cadmium(II)]-µ-pyridine-2,3-dicarboxyl-ato-κN,O:O].

The title polymeric compound, [Cd(C(7)H(3)NO(4))(H(2)O)(3)](n) or [Cd(py-2,3-dc)(H(2)O)(3)](n), where py-2,3-dcH(2) is pyridine-2,3-dicarboxylic acid, was obtained by the reaction of cadmium(II) nitrate hexa-hydrate with (pipzH(2))(py-2,3-dc) as a proton-transfer compound in aqueous solution (pipz is piperazine). The mol-ecular structure shows that only the anionic fragment of the starting proton-transfer compound is present in the complex, while the (pipzH(2))(2+) dication has been lost. Each (py-2,3-dc)(2-) ligand bridges two Cd(II) atoms in two different coordination modes, i.e. one end acts as a monodentate and the other end as a bidentate ligand. The three remaining coordination sites on the metal center are occupied by water mol-ecules. The geometric arrangement of the six donor atoms around the Cd(II) atom is distorted octa-hedral. In the crystal structure, O-H⋯O and C-H⋯O hydrogen bonds play an important role in stabilizing the supra-molecular structure.

Bis(piperazinediium) benzene-1,2,4,5-tetra-carboxyl-ate hexa-hydrate.

The title compound, 2C(4)H(12)N(2) (2+)·C(10)H(2)O(8) (4-)·6H(2)O or (pipzH(2))(2)(btc)·6H(2)O, was formed from the reaction between benzene-1,2,4,5-tetra-carboxylic acid (btcH(4)) as a proton donor and piperazine (pipz) as a proton acceptor. A variety of O-H⋯O, N-H⋯O and C-H⋯O hydrogen bonds, as well as C-H⋯π inter-actions, are present in the crystal structure. Two water O atoms are each disordered over two positions; for both the site occupany factors are ca 0.66 and 0.34.

Aqua-(1,10-phenanthroline)(pyridine-2,6-dicarboxyl-ato)nickel(II) pyridine-2,6-di-carboxylic acid solvate tetra-hydrate.

The title compound, [Ni(C(7)H(3)NO(4))(C(12)H(8)N(2))(H(2)O)]·C(7)H(5)NO(4)·4H(2)O or [Ni(pydc)(phen)(H(2)O)].pydcH(2)·4H(2)O, was obtained by the reaction of nickel(II) nitrate hexa-hydrate with the proton-transfer compound (phenH)(2)(pydc) (phen is 1,10-phenanothroline and pydcH(2) is pyridine-2,6-dicarboxylic acid) in aqueous solution. Both the cationic and anionic portions of the starting proton-transfer compound are involved in the complexation. The Ni(II) atom has a distorted octa-hedral geometry and is hexa-coordinated by three O atoms and three N atoms from one phen fragment (as a bidentate ligand), one (pydc)(2-) unit (as a tridentate ligand) and one water mol-ecule. In the crystal structure, extensive O-H⋯O, O-H⋯N and C-H⋯O hydrogen bonds with D⋯A distances ranging from 2.573 (2) to 3.385 (2) Å, π-π inter-actions between the phen ring systems [with centroid-centroid distances of 3.4694 (12), 3.4781 (11) and 3.8310 (11) Å] and inter-molecular C-O⋯π inter-actions [C⋯π distances of 3.4812 (17), 3.5784 (16) and 3.5926 (16) Å] connect the various components together.

Bis(guanidinium) bis-(4-hydroxy-pyridine-2,6-dicarboxyl-ato-κO,N,O)nickel-ate(II) dihydrate.

The reaction of nickel(II) nitrate hexa-hydrate, guanidine (G) and 4-hydroxy-pyridine-2,6-dicarboxylic acid (hypydcH(2)) in a 1:2:2 molar ratio in aqueous solution resulted in the formation of the title compound, (CH(6)N(3))(2)[Ni(C(7)H(3)NO(5))(2)]·2H(2)O or (GH)(2)[Ni(hypydc)(2)]·2H(2)O. The six donor atoms of the two 4-hydroxy-pyridine-2,6-dicarboxyl-ate or (hypydc)(2-) ligands form a distorted octa-hedral arrangement around the Ni(II) centre. Considerable C-O⋯π stacking inter-actions between the CO groups of carboxyl-ate fragments and the pyridine rings of (hypydc)(2-) with a distance of 3.3212 (8) Šare observed. In the crystal structure, a wide range of noncovalent inter-actions consisting of hydrogen bonding (of the types O-H⋯O and N-H⋯O), ion pairing, and π-π [centroid-centroid distance 3.8037 (5) Å], N-H⋯π and C-O⋯π stacking inter-actions connect the various components into a supra-molecular structure.