Copper(II) complex based on a V-shaped ligand, 2,6- bis (2-benzimidazolyl)pyridine: synthesis,crystal structure,DNA-binding properties,and antioxidant activities

A copper(II) complex based on a V-shaped ligand, 2,6-bis(2-benzimidazolyl)pyridine (bbp), has been synthesized and characterized by elemental analysis, molecular conductivity, ¹H NMR, IR, UV-Vis spectra, and X-ray single-crystal diffraction. The crystal structure of [Cu(bbp)₂](pic)₂?·?2DMF (pic?=?picrate) shows copper is six-coordinate forming a distorted octahedron. The interaction between Cu(II) complex and DNA was investigated by spectrophotometric methods and viscosity measurement. The experimental results suggest that the Cu(II) complex binds to DNA via intercalation. Antioxidant assay in vitro also shows that the Cu(II) complex possesses significant antioxidant activities.     

Rhenium(II) nitrosyl complexes: synthesis,characterization, DFT calculations and DNA nuclease activity

The rhenium(II) dinitrosyl and mononitrosyl complexes, i.e. [Re(NO)₂(CN)₄]·(Phen)₂·2H₂O (1) and PhenH[Re(NO)(CN)₄(H₂O)]·(Phen)·3H₂O (2) have been isolated and characterized. The X-ray crystal structure of 2 reveals that Re(II) is octahedrally coordinated with one nitrosyl, four cyanides, and one water, with one phenanthroline protonated to compensate the charge of the Re(II) center. The crystal structure shows chemically significant non-covalent interactions like hydrogen bonding involving the uncoordinated water and π–π interactions between phenanthrolinium and phen. The structures of both complexes have been optimized by DFT. Absorption and emission spectral studies and viscosity measurements indicate that both 1 and 2 interact with calf thymus DNA through partial intercalation of DNA bases. The intrinsic-binding constants, obtained from UV–vis spectroscopic studies, are 1.2?×?10⁴ and 7.2?×?10⁴?M^?1 for 1 and 2, respectively. Both 1 and 2 are capable of inducing cleavage of plasmid DNA in the presence of H₂O₂ to form the supercoiled form to nicked circular form. The spectroscopic results of DNA binding are supported by molecular docking studies.     

Structures and fluorescent properties of picolinato zinc(II) and cadmium(II) complexes based on tridentate and tetradentate benzimidazole ligands

Five picolinato zinc(II) and cadmium(II) complexes, [Zn(ntb)(pic)]ClO₄·CH₃OH·2H₂O (1), [Zn(bbma)(pic)]NO₃·2CH₃OH (2), [Cd(ntb)(pic)]ClO₄·0.75CH₃OH·H₂O (3), [Cd₂(bbma)₂(pic)₂](ClO₄)₂ (4), and [Cd₂(bbp)(bbp_-H)(pic)₂(C₂H₅OH)]ClO₄ (5), have been synthesized, where pic is the anion of picolinic acid, ntb is tris(2-benzimidazolylmethyl)amine, bbma is bis(benzimidazol-2-yl-methyl)amine, and bbp is 2,6-bis(benzimidazol-2-yl)pyridine. All the complexes were characterized by X-ray single-crystal diffraction, elemental analysis, IR, fluorescence spectroscopy, and thermal gravimetric analysis. 1–3 are mononuclear complexes in which picolinate adopts a N,O-chelating mode. 4 is a symmetrical dinuclear complex bridged by two anti-parallel picolinates in a N,O,O-coordination mode. 5 is also a dinuclear complex in which only one picolinate is a bridge. A 1-D double chain is formed by extensive H-bonds and π–π stacking in 1, while single zigzag chains are formed in 5. Complexes 2–4 all exhibit 6³-hcb 2-D frameworks. They extend to form four-connected 6⁶-dia 3-D topological nets for 2 and 4 and five-connected 4⁶·6⁴-bnn 3-D topological nets for 3. The five complexes show emission maxima in the blue region in the solid state.     

A tetradentate bisoxime and its supramolecular nickel(II) cluster: synthesis,crystal structure,and spectral properties

Salen-type bisoxime 5,5′-dimethoxy-2,2′-[(ethylenedioxy)bis(nitrilomethylidyne)]diphenol (H₂L) and its trinuclear Ni(II) cluster {[(NiL)(n-BuOH)]₂(μ-OAc)₂Ni}?·?n-BuOH have been synthesized and structurally characterized. The structure of H₂L adopts an L-shape conformation where the two salicylaldoxime moieties are well separated. In the trinuclear Ni(II) cluster, two acetates coordinate to three Ni(II)'s through Ni–O–C–O–Ni bridges, four μ-phenoxos from two [NiL(n-BuOH)] units also coordinate to Ni(II), and two n-butanols coordinate to two terminal Ni(II)'s forming a distorted octahedral geometry. The Ni–O–C–O–Ni and μ-phenoxo bridges play important roles in assembling Ni(II) and the ligands. H₂L forms a rectangle-like large cave structure through O–H?···?N, C–H?···?O, and C–H?···?π hydrogen-bond interactions, whereas its trinuclear Ni(II) cluster exhibits a 3-D supramolecular network structure through intermolecular O–H?···?O, C–H?···?O, and C–H?···?π hydrogen-bond interactions.     

Four silver-containing coordination polymers based on bis(imidazole) ligands

Four coordination polymers, [Ag(L¹)](m-Hbdc) (1), [Ag(L¹)]₂(p-bdc)?·?8H₂O (2), [Ag(Hbtc)(L¹)][Ag(L¹)]?·?2H₂O (3) and [Ag₂(L²)₂](OH-bdc)₂?·?4H₂O (4), where L¹?=?1,1′-(1,4-butanediyl)bis(imidazole), L²?=?1,2-bis(imidazol-1-ylmethyl)benzene, m-H₂bdc?=?1,3-benzenedicarboxylic acid, p-H₂bdc?=?1,4-benzenedicarboxylic acid, H₃btc?=?1,3,5-benzenetricarboxylic acid, and OH–H₂bdc?=?5-hydroxisophthalic acid, were synthesized under hydrothermal conditions. Compound 1 contains a–Ag-L¹–Ag-L¹–chain and a hydrogen-bonding interaction induced–(m-Hbdc)-(m-Hbdc)–chain. Compound 2 consists of two independent–Ag-L¹–Ag-L¹–chains. P-bdc anions are not coordinated. Hydrogen bonds form a 3D supramolecular structure. A novel (H₂O)₁₆ cluster is formed by lattice water molecules in 2. Compound 3 contains a–Ag-L¹–Ag-L¹–and a–Ag(Hbtc)-L¹–Ag(Hbtc)-L¹–chain. The packing diagram shows a 2D criss-cross supramolecular structure, with?π?···?π?and C–H ···?π?interactions stabilizing the framework. Compound 4 contains a [Ag₂(L²)₂]²⁺ dimer with hydrogen-bonding,?π?··· π, and Ag ··· O interactions forming a 3D supramolecular framework. The luminescent properties for these compounds in the solid state are discussed.     

Synthesis,crystal structure,and photophysical properties of a double open cubane-like Cd(II) complex based on 2-substituted-8-hydroxyquinoline

A 2-substituted-8-hydroxyquinoline (E)-2-[2-(3-thienyl)ethenyl]-8-quinolinol (HL) was synthesized and characterized by ESI-MS, NMR spectroscopy, and elemental analysis. Using solvothermal method, a tetranuclear complex [Cd₄L₆Br₂]·6DMF (1) was fabricated by assembly of Cd(II) with HL. X-ray structural analysis shows that 1 exhibits a double open cubane-like core structure, which is bridged by six 8-hydroxyquinolinate-based ligands. The supramolecular structure of 1 features a 3-D porous solid constructed by aromatic stacking interactions, C–H···π interactions and C–H···O hydrogen bonds. The assembly of cadmium salts and HL in solution was investigated by UV–vis and photoluminescence. We also studied the thermal stability and photophysical properties (fluorescent emission, lifetime, and quantum yield) of 1. The results show that 1 emits yellow luminescence in the solid state.     

Three multinuclear Co(II), Zn(II) and Cd(II) complexes based on a single-armed salamo-type bisoxime: syntheses,structural characterizations and fluorescent properties

Three multinuclear complexes, [Co(L)(OAc)Co(CH₃CH₂OH)₂]·H₂O, [Zn(L)(OAc)Zn(CH₃OH)], and [{Cd(L)(OAc)Cd(CH₃OH)}₂], containing a single-armed salamo-type bisoxime H₃L have been synthesized and characterized structurally. The Co(II) complex forms a dimeric unit by intermolecular hydrogen bond interactions of neighboring dimeric molecules. The Zn(II) complex also forms a dimeric unit by intermolecular hydrogen bond interactions. Interesting features of the crystal structure include O?O short contacts. Meanwhile, self-assembling infinite 1-D, 2-D, and 3-D supramolecular structures are formed by intermolecular hydrogen bond and C–H?π interactions. The Cd(II) complex forms an infinite 2-D supramolecular structure by intermolecular hydrogen bond interactions. The photophysical properties of the Co(II), Zn(II), and Cd(II) complexes have also been discussed.     

Dinuclear Zn(II) and Hg(II) complexes of an angular dipyridyl ligand: syntheses,crystal structures,and properties

The angular polytopic dipyridyl ligand 2,6-bis(quinoline-2-carboxamido)pyridine (H₂L) was prepared. Assemblies of H₂L with ZnAc₂ and HgAc₂ resulted in two new dinuclear complexes [Zn₂(L)(Ac)₂]?·?1.5H₂O?·?0.5CH₃OH (1) and [Hg₂(L)(Ac)₂]?·?5H₂O?·?CH₃OH (2) where the doubly deprotonated L^2? bi-chelate as μ-kN,N′?:?kN″,N″′, bridging the two metal centers (Ac?=?acetate). In 1, the two Zn(II) ions are also doubly bridged by two Ac ions in a μ-kO?:?kO′ coordination, and thus each metal center adopts a distorted tetrahedral geometry. In 2, each Ac ion is only terminal to Hg(II), in a rare distorted triangular or T-shaped coordination geometry. Free H₂L, 1, and 2 emit interesting bluish-green fluorescence with strong intensities. Thermogravimetric analysis of 1 shows that the dinuclear structure of 1 is stable to 382°C.     

Syntheses and structures of Cd(II) and Co(II) compounds of 4-[(3-pyridyl)methylamino]benzoate anion

Three coordination polymers containing Cd(II) and Co(II), connected via 4-[(3-pyridyl)methylamino]benzoate (L^?), have been synthesized in hydrothermal conditions. In [Cd(L)Cl] _n (1), adjacent Cd(II) cations are linked by carboxylates to give a dinuclear cluster. Pairs of L^? bridge the dinuclear cluster to form double helical chains, and these chains are further linked by Cl^? to produce a 4-connected net with (4²?·?6³?·?8) topology. [CdL₂] _n (2) contains 1-D ladder-like chains. The packing structure displays a 3-D supramolecular structure, with π?···?π interactions stabilizing the framework. [CoL₂] _n (3) has a 2-D extended supramolecular structure via π?···?π interactions of 1-D coordination polymers of 3. The crystal structures of 1–3 have been determined by single-crystal X-ray diffraction. Luminescent properties for 1 and 2 are discussed.     

Self-assembly of copper(II) complexes with substituted aroylhydrazones and monodentate N-heterocycles: synthesis,structure and properties

Two ternary copper(II) complexes [Cu(L¹)(py)] (1) and [Cu(L²)(Himdz]?·?CH₃OH (2) with substituted aroylhydrazones, 5-bromo-salicylaldehyde-3,5-dimethoxy-benzoylhydrazone (H₂L¹) and 5-bromo-salicylaldehyde-p-methyl-benzoylhydrazone (H₂L²), pyridine (py) and imidazole (Himdz), have been synthesized. Their crystal structures and spectroscopic properties have been studied. In each complex, the metal is in a square-planar N₂O₂ coordination formed by the phenolate-O, the imine-N and the deprotonated amide-O atoms of L^2?, and the sp²?N atom of the neutral heterocycle. In the solid state, 1 exists as a centrosymmetric dimer due to very weak apical coordination of the metal bound phenolate-O. Complex 2 has no such apical coordination and exists as a monomer. Self-assembly via C–H?···?O, N–H?···?O and O–H?···?N interaction leads to a one-dimensional chain arrangement; other non-covalent interactions such as C–H?···?π and π?···?π are not involved.     

cis-bis(Saccharinato)cobalt(II) and -zinc(II) complexes with 2-dimethylaminoethanol: syntheses,crystal structures,spectroscopic and thermal studies

2-Dimethylaminoethanol (dmea) reacted with tetraaqua-bis(saccharinato)cobalt(II) and -zinc(II) in n-butanol to yield the new complexes cis-[Co(sac)₂(dmea)₂] (1), and cis-[Zn(sac)₂(dmea)₂] (2) (sac?=?saccharinate). The complexes were characterized by elemental analyses, IR spectroscopy, DTA-TG and X-ray crystallography. Both complexes are isomorphous and crystallize in the monoclinic space group P2₁/c. The cobalt(II) and zinc(II) ions are coordinated by two neutral dmea ligands and two sac anions in a distorted octahedral environment. The dmea ligand acts as a bidentate N, O donor through the amine N and hydroxyl O atoms, while the sac ligand exhibits non-equivalent coordination, behaving as an ambidentate ligand; one coordinates to the metal via the carbonyl oxygen atom, while the other is N-bonded. The packing of the molecules in the crystals of both complexes is achieved by aromatic π(sac)–π(sac) stacking interactions, C–H?·?π interactions and weak intermolecular C–H?·?O hydrogen bonds involving the methyl groups of dmea and the sulfonyl oxygen atoms of the sac ligands. IR and UV spectra and thermal analysis are in agreement with the crystal structures.     

Crystal structures and DNA cleavage activities of two mononuclear nickel(II) complexes

Two new nickel complexes, [Ni(L₁)₂]?·?2(CH₃OH) (1) and [Ni(L₂)₂]?·?2(CH₃OH) (2), where HL₁ is 4-chloro-2-((2-hydroxy-ethylimino)methyl)phenol and HL₂ is 4-fluoro-2-((2-hydroxy-ethylimino)methyl)phenol, have been synthesized and characterized by single-crystal X-ray diffraction and UV-Vis absorption spectra. The coordination polyhedron of nickel(II) in each complex can be described as distorted octahedral. The interactions between the complexes and calf thymus (CT)-DNA/DNA were investigated by UV-Vis spectra and agarose gel electrophoresis. The results show that the complex transforms supercoiled to nicked form and exhibits effective DNA cleavage activity via hydrolytic cleavage mechanism.     

Zinc(II) complexes of 4,4-oxybis(benzoate) and 2-propyl-4,5-imidazoledicarboxylic acid with bipyridine

The reactions of dicarboxylic acids, such as 4,4-oxybis(benzoic acid) [H₂oba] and 2-propyl-4,5-imidazoledicarboxylate [H₃pimdc], under hydrothermal conditions in the presence of an appropriate zinc salt yield two mononuclear complexes, which are characterized by elemental analysis, infrared spectrum, electrochemical analysis, thermal analysis, and X-ray crystal diffraction. Complex 1, [Zn(Hoba)₂(4,4′-bpy)₂], forms a 2-D supramolecular layer like rhombus via hydrogen bonds (O–H?···?N). Complex 2, [Zn(H₂pimdc)₂(2,2′-bpy)]?·?H₂O, forms a zig-zag chain via multiple hydrogen bonds and C–H?···?π interactions. The moderate hydrogen-bond interactions in 1 and 2 play an important role for structural stability. The electrochemical analyses of 1 and 2 reveal electron transfer of 1 is reversible and 2 is quasi-reversible.     

Variation in crystalline architectures through supramolecular interactions in copper(II) complexes with tridentate N2O donor Schiff bases

Three copper(II) complexes, [Cu(L¹)(H₂O)(ClO₄)]·0.5H₂O (1), [Cu(L²)(H₂O)(ClO₄)]·0.5H₂O (2), and [Cu(L²)(NCNC(OCH₃)NH₂)]ClO₄ (3), where HL¹ = 4-bromo-2-(-(quinolin-8-ylimino)methyl)phenol and HL² = 1-(-(quinolin-8-ylimino)methyl)naphthalen-2-ol, have been prepared and characterized by elemental analysis, IR, UV–vis and fluorescence spectroscopy and single-crystal X-ray diffraction studies. The copper(II) centers assume five-coordinate square-pyramidal geometries in 1 and 2, whereas square planar copper(II) is present in 3. A methanol molecule has been inserted in the pendant end of the ligated dicyanamide in 3. Various supramolecular architectures are formed by hydrogen bonding, π?π, C–H?π, and lp?π interactions.     

Synthesis,structure, and DNA-binding properties of manganese(II) and zinc(II) complexes with tris(<Emphasis Type="Italic">N</Emphasis>-methylbenzimidazol-2-ylmethyl)amine ligand

Tris(N-methylbenzimidazol-2-ylmethyl)amine (Mentb) and its two complexes, [Mn(Mentb)(DMF)(H₂O)](pic)₂ 1 and [Zn(Mentb)(pic)](pic) 2 (pic = picrate), have been synthesized and characterized by physico-chemical and spectroscopic methods. Single crystal X-ray diffraction revealed that the two complexes have different structures. In complex 1, the coordination sphere around Mn(II) is distorted octahedral, whereas in complex 2 the coordination sphere around Zn(II) is distorted trigonal bipyramidal. The DNA-binding properties of the free ligand and its two complexes have been investigated by electronic absorption, fluorescence, and viscosity measurements. The results suggest that the ligand and its two complexes bind to DNA via an intercalation binding mode, and their binding affinity for DNA follows the order 1 > 2 > ligand.     

Four Zn(II)/Cd(II) coordination polymers derived from isomeric benzenedicarboxylates and 1,6-bis(triazol)hexane ligand: synthesis,crystal structure,and luminescent properties

Four coordination polymers, [Zn(o-bdc)(bth)_0.5(H₂O)] _n (1), [Cd(o-bdc)(bth)_0.5(H₂O)] _n (2), [Zn(m-bdc)(bth)] _n (3), and [Cd(p-bdc)(bth)?·?(H₂O)₂] _n (4) (where o-bdc?=?1,2-benzenedicarboxylate, m-bdc?=?1,3-benzenedicarboxylate, p-bdc?=?1,4-benzenedicarboxylate, and bth?=?1,6-bis(triazol)hexane), have been hydrothermally synthesized and structurally characterized. Both 1 and 2 are isostructural, featuring two binodal architectures: (6³)(6⁵·8) topology in terms of o-bdc and Zn^II/Cd^II as three- and four-connected nodes. Complex 3 shows a 2-D (4,4) network with the Zn?···?Zn?···?Zn angle of 57.84°, whereas 4 exhibits planar 2-D (4,4) network. These 2-D networks of 3 and 4 are extended by supramolecular interactions, such as CH?···?π/π–π stacking and hydrogen-bonding into 3-D architecture. A structural comparison of these complexes demonstrates that the dicarboxylate building blocks with different dispositions of the carboxyl site play a key role in governing the coordination motifs as well as 3-D supramolecular lattices. Solid-state properties such as photoluminescence and thermal stabilities of 1–4 have also been studied.     

Synthesis,crystal structures,and properties of copper(II) complexes with 2,6-bis(benzimidazol-2-yl)pyridine

Three new mononuclear copper(II) complexes, [CuL(2-fca)(CH₃OH)]ClO₄?·?CH₃OH (1), [CuL(m-nba)(CH₃OH)]ClO₄ (2), and [CuL(pic)(ClO₄)]?·?CH₃OH (3), were synthesized and structurally characterized, where L is 2,6-bis(benzimidazol-2-yl)pyridine, while 2-fca, m-nba, and pic are the anions of 2-furoic acid, m-nitrobenzoic acid, and picolinic acid, respectively. All of them were characterized by elemental analysis, infrared, UV-Vis, and X-ray crystallography. In 1 and 2, the Cu(II) resides within a distorted square-pyramidal N₃O₂ coordination sphere with three nitrogens of L, one carboxylate oxygen, and one methanol. In 3, Cu(II) is coordinated with three nitrogens of L, one nitrogen and one oxygen of picolinate, and one oxygen of perchlorate in a distorted octahedral geometry. Two molecules of 1, 2, and 3 are interacted by intermolecular hydrogen-bonding interactions and strong π–π stacking interactions to form a dinuclear structural unit. The dinuclear units are further connected by H-bonds via perchlorate or lattice methanol to form a 1-D chain for 1 and 2-D network structures for 2 and 3. Hydrogen-bonding and π–π stacking interactions are important for the stabilization of the final supramolecular structures of the three complexes.     

Structurally characterized dinuclear zinc(II) bis(salamo)‐type tetraoxime complex possessing square pyramidal and trigonal bipyramidal geometries

A novel dinuclear Zn(II) complex with the chemical formula [Zn₂(L)(OCH₃)] has been synthesized by a bis(salamo)‐type tetraoxime ligand based on 3‐bromo‐5‐chlorosalicylicaldehyde, and characterized by elemental analyses, IR, UV–vis, and fluorescent spectra, and single‐crystal X‐ray diffraction analysis. All the Zn(II) atoms are pentacoordinated by N₂O₂ donor atoms from the (L)³⁻ unit and one oxygen atom from one μ₂‐methoxyl group. The Zn(II) (Zn1 and Zn4) atoms have distorted square pyramidal geometries (τ₁ = 0.458, τ₄ = 0.388), whereas the Zn2 and Zn3 atoms adopt trigonal bipyramidal (τ₂ = 0.675, τ₃ = 0.550) geometries. The Zn(II) complex is self‐assembled by intermolecular C H···O interactions to form an infinite three‐dimensional supramolecular structure. Interestingly, the intermolecular C H···π interactions in the Zn(II) complex is involved not in the formation of three‐dimensional structures but rather in the formation of the 0D dimer structure. Meanwhile, the optical properties of the Zn(II) complex were also measured and are discussed.     

A new imidazophenanthroline derivative and its Hg(II) complex: structures,photophysical properties,and DFT calculations

A new ligand (L) and its mercury(II) complex have been synthesized under mild conditions. X-ray single-crystal structural analyses reveal 1-D, 2-D, and 3-D supermolecular structure of L and HgLI₂. Solvent molecules and various weak interactions, including hydrogen bonds (N–H···N, O–H···O, and O–H···N) and π–π interactions play signi?cant roles in the ?nal supermolecular structures. Detailed investigation on ¹H NMR spectra of L and HgLI₂ are presented. Their photophysical properties were investigated both experimentally and theoretically.     

Single‐armed salamo‐like dioxime and its multinuclear Cu (II), Zn (II) and Cd (II) complexes: Syntheses,structural characterizations,Hirshfeld analyses and fluorescence properties

Three multinuclear Cu (II), Zn (II) and Cd (II) complexes, [Cu₂(L)(μ‐OAc)]·CHCl₂ ( 1 ), [Zn₂(L)(μ‐OAc)(H₂O)]·3CHCl₃ ( 2 ) and [{Cd₂(L)(OAc)(CH₃CH₂OH)}₂]·2CH₃CH₂OH ( 3 ) with a single‐armed salamo‐like dioxime ligand H₃L have been synthesized, and characterized by FT‐IR, UV–vis, X‐ray crystallography and Hirshfeld surfaces analyses. The ligand H₃L has a linear structure and C‐H···π interactions between the two molecules. The complex 1 is a dinuclear Cu (II) complex, Cu1 and Cu2 are all five‐coordinate possessing distorted square pyramidal geometries. The complex 2 also forms a dinuclear Zn (II) structure, and Zn1 and Zn2 are all five‐coordinate bearing distorted trigonal bipyramidal geometries. The complex 3 is a symmetrical tetranuclear Cd (II) complex, and Cd1 is a hexa‐coordinate having octahedral configuration and Cd2 is hepta‐coordinate with a pentagonal bipyramidal geometry, and it has π···π interactions inside the molecule. In addition, fluorescence properties of the ligand and its complexes 1 – 3 have also been discussed.