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.     

Synthesis,characterization, and DNA-binding of a four-coordinate cobalt(II) complex with 1,3-bis(1-ethylbenzimidazol-2-yl)-2-oxopropane

A new four-coordinate cobalt(II) complex with 1,3-bis(1-ethylbenzimidazol-2-yl)-2-oxopropane (Etobb), Co(Etobb)Cl₂, has been synthesized and characterized by elemental analysis, electrical conductivities, infrared, and UV-Vis spectral measurements. The crystal structure has been determined by single-crystal X-ray diffraction. Cobalt(II) is a distorted tetrahedral geometry, surrounded by two nitrogens from Etobb and two chlorides. DNA-binding properties of Etobb and its Co(II) complex have been investigated by electronic absorption, fluorescence, and viscosity measurements. The experimental results suggest that the ligand and its Co(II) complex bind to DNA via intercalation, and the binding affinity of the Co(II) complex to DNA is greater than Etobb.     

Synthesis,crystal structure,and DNA-binding of a 3-D netlike supramolecular manganese picrate complex with 2,6-bis(benzimidazol-2-yl)pyridine

Manganese picrate with 2,6-bis(benzimidazol-2-yl)pyridine (L) has been prepared and characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. The complex crystallizes in the triclinic system, space group P–1 with a = 14.234(3) Å, b = 14.324(2) Å, c = 15.242(2) Å, α = 77.569(2)°, β = 63.350(3)°, γ = 82.130(2)°, and Z = 2. Interaction of the complex with calf-thymus DNA (CT-DNA) has been investigated with diverse spectroscopic techniques and viscosity measurements, and the binding constant is 1.76 × 10⁵ mol^?1. Results suggest that the complex bind to CT-DNA via intercalation.     

Syntheses,crystal structures,and DNA-binding of some nickel(II) complexes of 1,3-bis(2-pyridylmethylthio)propane and pseudohalides

A series of neutral octahedral nickel(II) complexes of 1,3-bis(2-pyridylmethylthio)propane (L) and pseudohalide (X), formulated as [Ni^II(L)X₂] (where X?=?azide (1), cyanate (2), and isothiocyanate (3)), was synthesized. The complexes were characterized by physico-chemical and spectroscopic methods, and 1 and 3 also by single-crystal X-ray diffraction analyses. The structural study shows nickel in a distorted octahedral geometry comprised of the tetradentate NSSN ligand with trans pyridines and monocoordinated pseudohalides in cis positions. In dimethylformamide solution, the complexes had quasi-reversible Ni^II/Ni^III redox couples in cyclic voltammograms with E _1/2 values of +0.732, +0.747, and +0.815?V for 1, 2, and 3, respectively. To examine the biological activities of these complexes, interaction of 3 with calf thymus DNA was studied spectroscopically, showing groove-binding interaction.     

A six-coordinate picrate cadmium(II) complex with a new V-shaped ligand 1,3-bis(1-ethylbenzimidazol-2-yl)-2-thiapropane: synthesis,crystal structure,and DNA-binding properties

A V-shaped ligand 1,3-bis(1-ethylbenzimidazol-2-yl)-2-thiapropane (L) and its picrate cadmium(II) complex have been synthesized and characterized systematically. In [Cd(L)₂](pic)_2, the Cd(II) is six-coordinate with N₄S₂ donors of two ligands, forming a slightly distorted octahedron. DNA binding properties were investigated by electronic absorption spectroscopy, fluorescence spectroscopy, and viscosity measurements. The compounds bind to DNA via intercalation and the order of binding affinity is ligand>complex.     

Synthesis,crystal structures,and DNA-binding studies of two silver(I) complexes with 1,3-bis(1-ethylbenzimidazol-2-yl)-2-thiapropane

Two new silver(I) complexes, [Ag(bebt)(methacrylate)] (1) and [Ag₂(bebt)₂](pic)₂ (2) (bebt = 1,3-bis(1-ethylbenzimidazol-2-yl)-2-thiapropane, pic = picrate), have been synthesized and characterized by physico-chemical and spectroscopic methods. Single-crystal X-ray diffraction revealed that the structure of 1 was four-coordinate in a distorted tetrahedral geometry, while in 2, it may be described as a 2 + 1 coordinated silver(I) compound with a nearly linear N–Ag–N backbone and a weak Ag–S interaction. Two ligands are arranged in a face-to-face syn conformation to coordinate to two Ag(I) ions from opposite directions in 2, generating a U-type double layer structure around the metal ions. Experimental studies of the DNA-binding properties indicated that free bebt and both complexes bind to DNA via intercalation, and the order of the binding affinity is 2 > 1 > bebt.     

Synthesis,structure, and antioxidative properties of a copper(II) complex with 1,2-bis(benzimidazol-2-yl)ethane ligand

1,2-Bis(benzimidazol-2-yl)ethane (bbe) and its copper(II) complex, {[Cu(bbe)Br₂]₂}·2DMF ( 1 ), have been synthesized and characterized by elemental analysis, ultraviolet–visible, and infrared spectra. The single crystal structure analysis of 1 shows two crystallographically independent but chemically identical [Cu(bbe)Br₂] molecules. The coordination geometry of the copper atoms may best be described as a distorted tetrahedron (τ₄ = 0.740 for Cu1 and 0.696 for Cu2). The cyclic voltammogram of complex 1 represents quasi-reversible Cu²⁺/Cu⁺ pairs. in vitro antioxidant tests showed that complex 1 has significant antioxidant activity against superoxide and hydroxy radicals. Photoluminescence investigations showed that the fluorescence intensity of complex 1 is significantly weaker than that of the ligand. This may be due to the paramagnetic effect of divalent copper to cause quenching of fluorescence.     

Structure,DNA-binding interaction and antitumour activity of two novel complexes coordinated by tridentate 1,3-bis(benzimidazol-2-yl)-2-oxapropane ligand

Two novel DNA-intercalating complexes, [Cd(hipa)(bbiop)] _n (1) and [Ni(ada)(bbiop)] _n ·2H₂O (2) with hipa, ada and potentially tridentate ligand bbiop (bbiop, 1,3-bis(benzimidazol-2-yl)-2-oxa-propane; hipa, 5-hydroxyisophthalate; ada, aniline-N,N-diacetate), have been synthesised under hydrothermal methods and structurally characterised by single crystal X-ray diffraction analysis, elemental analysis, UV–vis spectrum and fluorescent spectrum. The bbiop ligand exists as chelating-tridentate μ₁-(η₃–N₁, N₂, O₆) coordination fashion. In addition, their in vitro cytotoxicities towards four selected tumour cell lines have been evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method. Complex 1 exhibits the most dramatic inhibitory effect on MG-63, and its inhibition rate is higher than that of its free ligands, H₂bbiop and hipa, indicating significantly enhanced effect after forming complex. On the basis of the combination of UV–vis absorption and fluorescence titrations, complex 1 can interact with the base pairs of double-helical DNA via an intercalative mode with intrinsic binding constant, K _b, of 4.62 × 10⁷, presenting the high DNA-binding affinity.     

A Six-Coordinate Picrate Nickel(II) Complex Based on the V-Shaped Ligand 1,3-Bis (1-Benzylbenzimidazol-2-yl)-2-Thiapropane: Synthesis,Crystal Structure,Biological Activities

Abstract

A six-coordinate picrate nickel(II) complex based on the V-shaped ligand 1,3-bis(1-benzylbenzimidazol-2-yl)-2-thiapropane (L), with the composition [Ni(L)₂](pic)₂, has been synthesized and characterized systematically. The crystal structure of the Ni(II) complex is a six-coordinated octahedron, which is considerably close to ideal octahedral geometry with N₄S₂ donors of the two ligands. Biological activities of compounds were investigated using electronic absorption spectroscopy, fluorescence spectroscopy, and viscosity measurements. The results suggested that both ligand L and Ni(II) complex bind to DNA in an intercalative binding mode, and DNA-binding affinity of the Ni(II) complex is stronger than that of ligand L.

[Supplementary materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental files: Additional figures.]     

Ruthenium monoterpyridine complexes with 2,6-bis(benzimidazol-2-yl)pyridine: Synthesis,spectral properties and structure

Ruthenium monoterpyridine complexes with the tridentate 2,6-bis(benzimidazol-2-yl)pyridine (LH₂), [Ru(trpy)(LH₂)]²⁺, [1]²⁺ and [Ru(trpy)(L²⁻)], 2 (trpy = 2,2′:6′,2″-terpyridine) have been synthesized. The complexes have been authenticated by elemental analyses, UV–Vis, FT-IR, ¹H NMR spectra and their single crystal X-ray structures. Complexes [1]²⁺ and 2 exhibit strong MLCT band near 475 and 509 nm, respectively, and are found to be very much dependent on solution pH. The successive pH dependent dissociations of the N–H protons of benzimidazole moiety of LH₂ in [1]²⁺ lead to the formation of 2. The proton induced inter-convertibility of [1]²⁺ and 2 has been monitored via UV–Vis spectroscopy and redox features. The two pK_a values, 5.75 and 7.70, for complex [1]²⁺ have been determined spectroscopically.     

Synthesis,characterization, and DNA band of a five-coordinate cadmium(II) complex with 1,3-bis(1-benzylbenzimidazol-2-yl)-2-thiapropane

A five-coordinate cadmium(II) complex with 1,3-bis(1-benzylbenzimidazol-2-yl)2-thiapropane (L), [Cd(L)Br₂]?·?DMF, has been synthesized and characterized by elemental analysis, electrical conductivities, IR, and UV-Vis spectral measurements. The crystal structure of the complex has been determined by single-crystal X-ray diffraction. The Cd(II) is five-coordinate with two nitrogens and a sulfur from one ligand, and two bromides. The N₂SBr₂ donors are in a distorted square-pyramidal geometry (τ?=?0.32). Electronic absorption titration spectra, EB (ethidium bromide) competitive experiment, and viscosity measurement indicated that the complex can bind to DNA via intercalation.     

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.     

Syntheses,crystal structures,and fluorescent properties of two 2-D Cd(II) complexes based on 2-((1H-1,2,4-triazol-1-yl)methyl)-1H-benzimidazole and 1,2,4,5-benzenetetracarboxylate

Two complexes formulated as {[Cd(btec)_0.5(tmb)H₂O]·4H₂O}_n (1) and {[Cd(H₂btec)(tmb)(H₂O)]·2H₂O}_n (2) (H₄btec?=?1,2,4,5-benzenetetracarboxylic acid, tmb?=?2-((1H-1,2,4-triazol-1-yl)methyl)-1H-benzimidazole) have been synthesized and characterized by elemental analysis, IR, and single crystal X-ray diffraction. Single crystal X-ray diffraction shows that 1 has a 2-D layer structure in which tmb bridges and all of the carboxylates from 1,2,4,5-benzenetetracarboxylate chelate. In 2 Cd(II) ions are bridged by monodentate carboxylates leading to a 2-D layer structure with all tmb ligands coordinated monodentate to Cd(II), hanging at two sides of the layers. Complexes 1 and 2 are further extended to 3-D supramolecular structures by hydrogen bonding interactions. Luminescent properties have been investigated in the solid state at room temperature.     

1,3-双(2-苯并咪唑基)-2-氧杂丙烷与锌配合物的合成、晶体结构及其与DNA作用方式的研究

合成了1,3-双(2-苯并咪唑基)-2-氧杂丙烷合锌(II)配合物, 并用元素分析和X射线衍射进行了表征, 表明其为畸变八面体构型. 用紫外、DNA熔点、荧光、粘度等手段对其与小牛胸腺DNA作用方式进行了研究. 实验结果表明, 由于配合物的八面体构型以及苯并咪唑环的平面性, 其与DNA作用方式可能为部分插入.     

Copper(II) complexes with 2,5-bis(2-pyridyl)pyrazine and 1,1,3,3-tetracyano-2-ethoxypropenide anion: Syntheses,crystal structures and magnetic properties

The copper(II) complexes of formula [Cu₂(2,5-dpp)(H₂O)₄(CF₃SO₃)₄] · 2H₂O (1) and [Cu₂(2,5-dpp)(H₂O)₂(tcnoet)₄]_n (2) [2,5-dpp = 2,5-bis(2-pyridyl)pyrazine and tcnoet⁻ = 1,1,3,3-tetracyano-2-ethoxypropenide anion] have been prepared and their structures determined by X-ray crystallographic methods. Compound 1 is a dinuclear complex where the 2,5-dpp molecule acts as a bis-bidentate bridge between the two copper centers, the electroneutrality being achieved by four terminally bound triflate anions. Each copper(II) ion presents an elongated octahedral CuN₂O₄ environment with two nitrogen atoms from 2,5-dpp and two water molecules in the basal plane and two triflate-oxygen atoms in the axial positions. Compound 2 is a zigzag chain of copper(II) ions with regular alternating 2,5-dpp and double tcnoet groups as bridges. Each copper(II) ion exhibits an elongated octahedral CuN₅O surrounding with four nitrogen atoms, two from 2,5-dpp, one from a terminally bound tcnoet and the other from a bridging tcnoet occupying the equatorial positions and a water oxygen and a nitrogen from a monodentate tcnoet in the axial sites. The values of the copper–copper separation across 2,5-dpp are 6.763(1) (1) and 6.754(1) Å (2) whereas that through the double tcnoet bridge is 9.559(1) Å (2). The investigation of the magnetic properties of 1 and 2 in the temperature range 1.9–295 K reveal a Curie law behaviour for 1 and a very weak ferromagnetic interaction for 2. The poor ability of the 2,5-dpp ligand to mediate magnetic interactions between the copper(II) ions in the 2,5-dpp-bridged copper(II) complexes contrast with the somewhat better ability of the pyrazine ring in related pyrazine-bridged copper(II) complexes.     

Syntheses and crystal structures of two supramolecular isomers of manganese(II) with 3,5-bis(isonicotinamido)benzoate

Two new supramolecular isomeric complexes [Mn(BBA)₂(H₂O)₂] _n · 4nH₂O (1) and [Mn(BBA)₂(H₂O)₂] · 4H₂O (2) were obtained by hydrothermal reactions of MnCl₂ · 4H₂O with 3,5-bis(isonicotinamido)benzoic acid (HBBA) under different ratio of NaOH/HBBA. Complex 1 is a 1-D zigzag chain in which the Mn(II) is six-coordinate with distorted octahedral geometry. The 1-D chains are further connected by hydrogen bonds to give a 3-D supramolecular framework. Complex 2 is a monomeric molecular complex, assembled through intermolecular hydrogen bonds into a 3-D supramolecular network. Reaction conditions have remarkable influence on the structures of the complexes. The thermal and non-linear optical properties of the complexes were studied.     

2,6-二(2-苯并咪唑基)吡啶与稀土苦味酸盐配合物的合成、晶体结构及荧光性质研究

合成了稀土苦味酸盐(pic)与配体2,6-二(2-苯并咪唑基)吡啶(L)的配合物,通过元素分析、红外光谱及电子光谱对配体及配合物进行了表征,并用X射线单晶衍射测定了配合物[CeL2(pic)2](pic)?(CH3OH)3的晶体结构.配合物属于三斜晶系,空间群为P-1,晶胞参数a=1.3795(3)nm,b=2.1292(5)nm,c=2.5651(6)nm,α=105.847(3)°,β=100.150(3)°,γ=107.893(3)°,Z=2,R=0.0519,wR=0.1255.晶体中一个不对称单元内有两个结晶学上独立的分子,这两个分子的构型基本相同,中心Ce3 均与两个三齿配位的配体及两个双齿配位的苦味酸根配位,配位数为10.中心Ce3 的配位多面体为变形双帽四方反棱柱,两个分子之间以π-π堆积连接,生成一个非中心对称的二聚体.整个晶体则是由这些二聚体以分子间氢键作用连接成三维网状超分子结构.室温下,在紫外光激发下Eu(III)配合物固体和溶液均表现出中心离子的特征荧光发射.     

Syntheses,crystal structures and antibacterial activities of two new Mn(II) complexes based on triaryltriazoles

Two new Mn(II) complexes, trans-[Mn(L1-L2)₂(NCS)₂] (1–2) with triaryltriazole (1, L1 = 3-(p-bromophenyl)-4-phenyl-5-(2-pyridyl)-1,2,4-triazole; 2, L2 = 3,4-bis(p-methylphenyl)-5-(2-pyridyl)-1,2,4-triazole), have been synthesized and structurally characterized by elemental analysis, FT-IR, ESI-MS, and single-crystal X-ray crystallography. Crystallographic studies revealed that both 1 and 2 contain a distorted octahedral [MnN₆] core with two trans-disposed NCS^? ions. The L1 ligand, 1 and 2, together with four known homologous Mn(II) complexes, trans-[Mn(L3-L6)₂(NCS)₂] (3–6) (3, L3 = 3-(p-methoxyphenyl)-4-(p-chlorophenyl)-5-(2-pyridyl)-1,2,4-triazole; 4, L4 = 3-(p-methoxyphenyl)-4-(p-bromophenyl)-5-(2-pyridyl)-1,2,4-triazole; 5, L5 = 3-(p-chlorophenyl)-4-(p-methylphenyl)-5-(2-pyridyl)-1,2,4-triazole; 6, L6 = 3,5-bis(2-pyridyl)-4-(p-methylphenyl)-1,2,4-triazole), were tested in vitro for their antibacterial activities against two Gram-positive bacterial strains and two Gram-negative bacterial strains by the MTT method. The results indicate that 1 exhibited better activity than Penicillin and Kanamycin against Pseudomonas aeruginosa and also better than its free L1 ligand.     

Syntheses and crystal structures of two Schiff-base copper(II) complexes with urease inhibition

Two new copper(II) complexes, [CuL1(N₃)] (1) and [CuL2(NCS)] (2) (HL1 = 4-chloro-2-[(2-piperidin-1-ylethylimino)methyl]phenol, HL2 = 4-chloro-2-[(2-morpholin-4-ylethylimino)methyl]phenol), were prepared and structurally characterized by elemental analyses, infrared spectroscopy, and single-crystal X-ray diffraction. Complex 1 is an azide coordinated mononuclear complex, while complex 2 is a terminal thiocyanate coordinated mononuclear complex. The coppers in both complexes are four-coordinate, square-planar. Both complexes show potent urease inhibitory properties.     

Four 1,3-bis(1,2,4-triazol-1-yl)propane-based metal complexes tuned by competitive coordination of mixed ligands: synthesis,solid structure,and fluorescence

Four 1,3-bis(1,2,4-triazol-1-yl)propane (btp)-based transition metal complexes, {[Zn(btp)₃] ?(ClO₄)₂} _n (1), [Zn(btp)₂(dca)₂] _n (2), [Zn(btp)(NCS)₂] (3), and [Mn(btp)₂(NCS)₂] _n (4), have been obtained by introducing small anionic coligands and structurally characterized by single crystal X-ray diffraction, elemental analysis, IR spectra, thermogravimetric curves, and solid luminescence spectra. Structural determinations reveal that the polymeric triple-stranded chain for 1 without coligand is changed into 1-D double-stranded chains for 2 and 4, and discrete binuclear structure for 3. Compared with 1, the mixed-ligand complexes are moderately destabilized for 2 and 4, and slightly enhanced for 3. Additionally, the four solid complexes exhibit strong emissions, suggesting their potential applications as luminescent materials.