Synthesis,structure and magnetism of a hydrogen-bond-linked three-dimensional network of a novel nickel(II)–cobalt(II)–nickel(II) complex containing a new macrocyclic mononuclear complex ligand

A novel trinuclear complex, [Co(NiL)₂(H₂O)₂](ClO₄)₂ · 2C₂H₅OH, was prepared by self-assembly using [NiL] as a new complex ligand; L is the dianion of dimethyl 5,6,7,8,15,16-hexahydro-6,7-dioxodibenzo[1,4,8,11]tetraazacyclotetradecine-13,18-dicarboxylate. The structure of the trinuclear complex was determined by X-ray crystallography. The Co^II ion is at the center of the trinuclear complex cation and occupies a distorted octahedral O₆ environment, approximating to O _h with a ⁴ T _1g ground state for Co^II that has an unquenched spin–orbit coupling reflected in the magnetic properties. Two Ni^II ions reside in completely same and slightly distorted square-planar N₄ coordination geometries. Co^II and each Ni^II are bridged by an oxamido group from one of the two macrocyclic ligands (L). O—H...O and ... interactions link the trinuclear fragments, perchlorate ions and C₂H₅OH molecules to form a three-dimensional supramolecular architecture.     

A helical polymeric complex,tris(benzimidazole)nickel(II) (μ-maleato)

The title polymeric complex [Ni(C₇H₆N₂)₃(C₄H₂O₄)] _n has been prepared and its crystal structure determined by single-crystal X-ray diffraction methods. The complex is orthorhombic, space group P2₁2₁2₁ with a?=?9.320(1), b?=?12.015(1), c?=?20.964(2)?Å. Three benzimidazole (bzim) and two maleate dianions coordinate to the Ni(II) atom with distorted octahedral geometry. Maleate dianions bridge neighbouring Ni(II) atoms through terminal carboxyl groups, one in monodentate and the other in chelate mode, to form polymeric molecular chains extending along the a axis. The structure is chiral, the Flack index of 0.002(10) suggesting that the helical polymeric chain is right-handed. Both intra-helical and inter-helical N–H···O hydrogen bonding occurs between bzim and carboxyl groups of maleate. The partially overlapped arrangement of nearly parallel bzim rings suggests the existence of π–π stacking in the crystal.     

Nickel(II) thiosemicarbazone complex catalyzed Mizoroki–Heck reaction

Convenient synthesis of a new square planar nickel(II) naphthaldehyde thiosemicarbazone complex has been described. The composition of the complex has been established by elemental analysis, spectral methods, and single crystal X-ray crystallography. The new complex acts as an active homogeneous catalyst for the Mizoroki–Heck reaction of electron deficient (activating) and electron rich (deactivating) aryl bromides with various olefins under optimized conditions.     

Reactivity of nickel(II) and copper(II) complexes of a β-aminohydrazone ligand with pyridine-2-aldehyde: macrocyclization vs unprecedented pyrazole ring synthesis via C-C bond-forming reaction

The synthesis and characterization of a mononuclear nickel(II) complex [Ni(L(2))](ClO(4))(2) (1) and an analogous mononuclear copper(II) complex [Cu(L(2))](ClO(4))(2) (2) of a 15-membered azamacrocycle (L(2) = 3-(2-pyridyl)-6,8,8,13,13,15-hexamethyl-1,2,4,5,9,12-hexaazacyclopentadeca-5,15-diene) are reported. The macrocyclic ligand is formed during the reaction of 4,4,9,9-tetramethyl-5,8-diazadodecane-2,11-dione dihydrazone (L(1)) with pyridine-2-aldehyde (PyCHO) templated by metal ions. The X-ray crystal structure of 1 exhibits a distorted square-pyramidal coordination geometry, where the metal ion sits in the macrocyclic cavity and the pendant pyridine group of L(2) occupies the axial position. While 1 is stable in the presence of an excess of PyCHO, 2 reacts further with copper(II) salt and PyCHO to form a mononuclear copper(I) complex, [Cu(H(2)L(3))](ClO(4))(3) (3). The structure of the complex cation of 3 reveals a distorted tetrahedral coordination geometry at the copper center with a pseudo 2-fold screw axis. A two-dimensional (2D) polymeric copper(II) complex, {[Cu(2)(L(4))(2)](ClO(4))(2)}(n) (4) is obtained by reacting complex 2 (or [Ni(L(1))](ClO(4))(2)) with copper(II) perchlorate and pyridine-2-aldehyde in a methanol-water solvent mixture. Complex 4 is also obtained by treating 3 with copper(II) perchlorate and pyridine-2-aldehyde in the presence of a base. The X-ray structural analysis of 4 confirms the formation of a pyrazolate bridged dimeric copper(II) complex. The extended structure in the solid state of 4 revealed the formation of a 2D coordination polymer with the dimeric core as the repeating unit. The ligand (HL(4)) in 4 is a 3,4,5-trisubstituted pyrazole ring formed in situ via C-C bond formation and represents an unprecedented transformation reaction.     

Complexes of tris(o-phenanthroline)nickel(II) and copper(II) bromide with dithiocarbamates derived from α-amino acids

Complexes of 1,10-o-phenanthroline (o-phen)-Ni^II and Cu^II with dithiocarbamates derived from -amino acids (glycine, phenylalanine, alanine, methionine and tryptophan) were synthesized and characterized by chemical analysis, spectral and thermal studies and by biological screening; the complexes are non-electrolytes. The empirical formula are [Ni(o-phen)₂(aadtc)] and [Cu₂(o-phen)₂(phaladtc)(H₂O)₂Br₂] where, aadtc = glycinyl-, phenylalaninyl-, alaninyl-, methioninyl- and tryptophanyldithiocarbamate and phaladtc = phenylalaninyldithiocarbamate. The structure of these complexes is probably octahedral. Molecular association through hydrogen bonding between the —NH and the carboxylate groups is proposed for the Ni^II complexes. The Cu^II complex is dimeric with the phenylalaninyldithiocarbamate acting as a bridge.     

Aluminium–SALEN complex: a new catalyst for the enantioselective Michael reaction

A new heterobimetallic complex prepared from a chiral SALEN ligand and Red-Al® was found to catalyse the Michael reaction between various dialkyl malonates and cycloalkenones to give products in high yields with e.e.s of up to 58%.     

Unusual formation of β-carboline dimers under Bischler-Napieralski reaction conditions: an old reaction with a new direction

l-N-Formyl tryptophan methyl ester (3) underwent a Bischler-Napieralski reaction with POCl₃ at room temperature or under microwave irradiation, resulting in the unusual formation of β-carboline dimers 5 and 6. Most importantly, acetylation using Ac₂O of each of the dimers 5 and 6 separately afforded 1-[3′-carbomethoxy-β-carbolinyl]-3-carbomethoxy-9-acetyl-β-carboline (7) as the only product, the structure of which was confirmed by X-ray crystallography studies.     

β-Fe2O3 nanomaterials from an iron(II) diketonate-diamine complex: a study from molecular precursor to growth process

Iron oxide is a key multi-functional material in many different fields of modern technology. The β-Fe(2)O(3) cubic phase, one of the least studied Fe-O systems, was obtained by Chemical Vapor Deposition (CVD) using for the first time a Fe(II) β-diketonate diamine complex, Fe(hfa)(2)·TMEDA, as the molecular source (hfa = 1,1,1,5,5,5-hexafluoro-2,4-pentanedionate; TMEDA = N,N,N',N'-tetramethylethylenediamine). The strong visible light absorption of β-Fe(2)O(3) deposits highlights their possible functional application in photocatalytic hydrogen production under solar light. A comprehensive investigation on the Fe(ii) complex, performed by a joint experimental-theoretical approach, explains the molecular origin of its excellent thermal behaviour and reveals why this species is a successful precursor for the CVD of iron oxide nanostructures.     

A pseudo trinuclear nickel–sodium complex containing tris(8-methyl-2-oxo-quinolidineamino ethylamine): Synthesis,spectral characterization,X-ray crystallography and in vitro biological evaluations

A new mixed nickel–sodium complex has been synthesized from Ni(ClO₄)₂ and tris(8-methyl 2-oxo-quinolidine amino ethylamine) with a 1:1 molar ratio in methanol and has been characterized by various analytical, spectroscopy and X-ray diffraction studies which confirmed an octahedral geometry around the nickel ion. Further, structural optimization of the complex was performed using DFT calculations. The ligand and complex were evaluated for their binding affinity with CT-DNA and an intercalative type of binding interaction was proposed from the absorption and fluorescence titration experiments. Albumin binding interaction of the ligand and complex was determined by absorption, fluorescence and synchronous spectral techniques at room temperature, suggesting the static quenching mechanism of BSA with the compounds. Antioxidant studies revealed the radical scavenging potential of Ni(II) complex. The anticancer activity of the ligand and complex was probed via in vitro cytotoxicity against human breast (MCF7) and lung (A549) cancer cell lines by MTT assay. Further, cytological changes observed in acridine orange/ethidium bromide and DAPI staining methods validated the cytotoxic potential of the complex.     

Synthesis and enantiomer separation of a modified tris(2,2′-bipyridine)ruthenium(II) complex

The chiral [5-(4-hydroxybutyl)-5′-methyl-2,2′-bipyridine]-bis(2,2′-bipyridine)-ruthenium(II)-bis(hexafluoroantimonate) complex 3 was prepared and characterized by different NMR techniques and successfully separated into enantiomers by electrokinetic chromatography using anionic carboxymethyl-β-cyclodextrin as chiral mobile phase additive (CMPA). The optimum separation conditions were obtained with 40 mM borate buffer at pH 9.5 and 7.5 mg/mL of the chiral selector at 20°C.     

Preparation,structure and magnetic study of a new linear 1-D Cu(II)–Gd(III) coordination polymer

A carboxylate-bridged Cu(II)–Gd(III) complex, [GdCu(CH₂CH(CH₃COO)₄(H₂O)₄] _n (NO₃) _n , was prepared and characterized. Single crystal X-ray analysis reveals the complex as a carboxylate-bridged 1-D Cu(II)–Gd(III) coordination polymer. The magnetic measurement showed this complex exhibiting weak ferromagnetic behavior.     

A new 3-D microporous Ln(III)–Cu(I) framework constructed by pyridine-3,5-dicarboxylate

A new 3-D lanthanide-transition metal coordination polymer [LaCu(PDC)₂H₂O] _n (1) was hydrothermally synthesized from pyridine-3,5-dicarboxylic acid (H₂PDC) and characterized by single-crystal X-ray diffraction, IR spectroscopy, and thermal gravimetric analysis (TGA). The microporous framework of 1 can be viewed as constructed by planar binuclear Cu₂(PDC)₄ building blocks and La(III) chains, a new structural motif in 3d-4f heterometallic coordination polymers. The sample exhibits strong blue emission in the solid state and retains its framework integrity up to ca 380°C.     

Cation-templated 2-D Mn(II)–oxalate framework with an acyclic tetrameric water cluster

The single-crystal X-ray structure of a cation-templated manganese–oxalate coordination polymer [NH(C₂H₅)₃][Mn₂(ox)₃]?·?(5H₂O)] (1) is reported. In 1, triethylammonium cation is entrapped between the cavities of 2-D honeycomb layers constructed by oxalate and water. The acyclic tetrameric water clusters and discrete water assemble the parallel 2-D honeycomb oxalate layers via an intricate array of hydrogen bonds into an overall 3-D network. The magnetic susceptibility, with and without the water cluster, are reported with infrared and EPR studies.     

Xylan-type hemicelluloses supported terpyridine–palladium(II) complex as an efficient and recyclable catalyst for Suzuki–Miyaura reaction

Xylan-type hemicelluloses supported terpyridine–palladium(II) as a novel biomass-supported catalyst was synthesized and characterized in terms of morphology, composition, and thermal stability. The nano-Pd catalyst was further explored for Suzuki–Miyaura reaction between arylboronic acid and aryl halide under aerobic condition, with a yield up to 98 %. In particular, the catalyst exhibited both high catalytic activity and stability for Suzuki–Miyaura reaction. Furthermore, the catalyst could be easily recovered by simple filtration and reused at least six times without significant loss of its catalytic activity. This work provides a novel and effective supported catalyst, and broadens the applications of polysaccharides in green catalysis.     

Immobilization of a palladium(II) bis(imidazolium) complex onto graphene oxide by noncovalent interactions: an efficient and recyclable catalyst for Suzuki–Miyaura reaction

In this research, the Suzuki–Miyaura coupling reaction catalyzed by a palladium(II) complex containing bis(imidazolium) ligand, Pd^II(BIM), immobilized on graphene oxide (GO) as heterogeneous, recyclable and active catalyst is reported. The catalyst, Pd^II(BIM)@GO, was characterized by FT-IR, diffuse reflectance UV–Vis spectroscopy, ICP, field emission scanning electron microscopy, energy-dispersive X-ray analysis, and elemental analysis. It was demonstrated that the GO-supported palladium(II) complex can act as an efficient catalyst and is reusable several times without a significant loss of their catalytic activity.     

Synthesis of a new complex Chromium (Ⅲ) 2-mercaptonicotinate

Chromium is an essential trace element for mammals[1-3].Diabetes is a chronic disease with major health consequence.Studies show that the occurrence of diabetes have great thing to do with the chromium deficient。Almost 40 years after the first report of glucose tolerance factor(GTF) [4] no conclusive evidence for an isolable ,biologically active form of chromium exited。Three materials have been proposed to be the biologically active form of chromium:“glucose tolerance factor”,chromium Pi…     

A new tetranuclear copper(II) complex containing decameric water clusters bridged by–OH–and pyridine-2,4, 6-tricarboxylate: synthesis and magnetic characterization

Using pyridine-2,4,6-tricarboxylic acid (H₃ptc) and 2,2-bipyridine (2,2-bipy), a tetranuclear copper(II) compound [Cu₄(2,2-bipy)₄(ptc)₂(H₂O)₂(OH)₂] · 12H₂O (1) has been isolated under hydrothermal conditions. Variable temperature magnetic susceptibility of 1 from 2–300 K indicates anti-ferromagnetic interactions. The magnetic exchange coupling constants of J = ?159.4 and J′ = ?18.66 cm^?1 for 1 can be obtained through fit of the magnetic data, corresponding to two kinds of bridges, hydroxyl anions (OH^?) and pyridine carboxylate oxygen of ptc^3?. Moreover, decameric water clusters can also be observed, which are located between these tetranuclear copper(II) entities, forming a series of intricate O-H ··· O hydrogen bonds and stabilizing the resulting three-dimensional (3-D) hydrogen-bonded framework structure.     

Electrogeneration and characterization of a poly(pyrrole–nickel (II) chlorin) electrode

We describe herein, the electrochemical properties of an hydroporphyrin of Ni(II) substituted by two pyrrole groups in organic media (THF and CH₂Cl₂). In the anodic region it has been shown that the electrochemical behaviour of this complex investigated by cyclic voltammetry and coulometry coupled with UV–visible spectroscopy is strongly dependent on the nature of the solvent.Furthermore, the electrochemical oxidation of the pyrrrole groups has led to the first example of an electrogenerated polypyrrole–metallochlorin film. The resulting modified electrodes exhibit the same electrochemical properties as the monomer free in solution. Preliminary experiments have also demonstrated the possibility to study electrochemically this polymeric film in CH₃CN contrary to the Ni(II) chlorin, which is insoluble in this medium.     

A photoluminescent dinuclear phenylquinolyl Ir(II)-Ir(II) complex featuring a μ-η1:η2-phenylquinolyl bridge and an end-on dinitrogen ligand

The synthesis, characterization and photoluminescent properties of a dinuclear Ir complex with a μ-η(1):η(2)-phenylquinolyl bridge and an end-on dinitrogen ligand are reported herein. DFT studies on its electronic structure and photophysical properties are also presented.