Ruthenium monoterpyridine complexes with 2,6-bis(benzoxazol-2-yl)pyridine as an ancillary ligand: Synthesis,structure and spectral studies

Ruthenium monoterpyridine complexes, [1]⁺ and [2]²⁺, with 2,6-bis(benzoxazol-2-yl)pyridine as an ancillary ligand, L, have been synthesized and characterized by UV–Vis, FT-IR and ¹H NMR spectroscopic techniques. The formulations of the complexes were confirmed by the single crystal structure of their perchlorate salts. In both complexes, the Ru^II center is hexa-coordinated in a distorted geometry. In complex [1]⁺, the ancillary ligand L behaves as a bidentate ligand; in [2]²⁺, however, it binds the metal center as a tridentate ligand. The central pyridine nitrogen of terpyridine (N_p,trpy) is in a cis position with respect to the central pyridine nitrogen of the ancillary ligand (N_p,benz) in complex [1]⁺ and in a trans-position in complex [2]²⁺. The cis orientation of N_p,trpy and N_p,benz in complex [1]⁺ forces L to behave as bidentate. The quasi-reversible Ru^II/Ru^III couple appears at 0.90 and 1.44 V versus SCE in the case of complex [1]⁺ and [2]²⁺, respectively. [1]⁺, in the presence of aqueous AgNO₃, affords [2]²⁺ through an intramolecular dissociative interchange pathway.     

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,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 properties of two nickel(II) complexes with 1,3-bis(benzimidazol-2-yl)-2-oxapropane derivatives

[Ni(obb)(DMF)₂(H₂O)]·(Pic)₂·0.5DMF (1) and [Ni(Etobb)₂]·(Pic)₂·2DMF (2) (obb = 1,3-bis(benzimidazol-2-yl)-2-oxapropane, Etobb = 1,3-bis(1-ethylbenzimidazol-2-yl)-2-oxapropane, Pic = picrate) have been synthesized and characterized by physicochemical and spectroscopic methods. The structures of both complexes have been determined by X-ray single-crystal diffraction. The coordination geometries of 1 and 2 can be described as distorted octahedra. The interaction of the nickel(II) complexes with calf thymus DNA was investigated by electronic absorption, fluorescence spectroscopy, and viscosity measurements. The experimental results suggest that 1 and 2 bind to DNA in an intercalation mode, and their binding affinity for DNA follows the order 1 > 2. DNA-binding behaviors can be attributed to the large coplanar aromatic rings in the V-shaped ligand and steric hindrance.     

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.     

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.     

Synthesis,spectral and electrochemical properties of mixed-ligand ruthenium(II) complexes of bis(pyrid-2-yl)- and bis(benzimidazol-2-yl)-dithioether ligands: Effect of an asymmetric diimine co-ligand

Two new mixed-ligand Ru(II) complexes [Ru(pdto)(dppt)](ClO₄)₂ (1) and [Ru(bbdo)(dppt)](ClO₄)₂ (2), where pdto = 1,8-bis(pyrid-2-yl)-3,6-dithiaoctane, bbdo = 1,8-bis(benzimidazol-2-yl)-3,6-dithiaoctane and dppt = 3-(pyridin-2-yl)-5,6-diphenyl-1,2,4-triazine, have been isolated and characterised by elemental analysis. NMR and electronic absorption and emission spectral and electrochemical techniques have been used to investigate the solution structures and electronic properties of the complexes. The ¹H and ¹³C spectra of the complexes in solution reveal that the N₂S₂ donor set of the pdto and bbdo ligands is “cis-α” coordinated and the dppt ligand is chelated to Ru(II) through both triazine N2 and pyridine nitrogen atoms. The proton chemical shifts of the phenyl rings of dppt are not affected much upon coordination, supporting the triazine N2 rather than N4 coordination. The anomalous upfield shifts of the H₆₁ and H₆₂ (1) and H₇₂ and H₈₁ (2) protons are caused by the shielding magnetic anisotropy due to the ring currents of the py and tra rings of dppt, which are forced to be coplanar by coordination. The py and bzim rings of pdto and bbdo are obliged to rotate away from dppt and the Ru–N_py and Ru–N_bzim bonds lengthen in order to minimise the steric clashes with dppt. The c.i.s values for 1 are less positive than those for 2 suggesting that the ligand bzim nitrogens of bbdo rather than the py nitrogens of pdto are involved in stronger σ-bonding with Ru(II). Both the complexes display a strong MLCT transition (1, 470; 2, 515 nm) along with intense intraligand transitions in the UV region, and when excited in the MLCT band an emission band (650 nm) is observed for both 1 and 2. In acetonitrile solution they show a quasi-reversible Ru(II)/Ru(III) redox couple (E_1/2, 1, 1.18; 2, 0.90 V). Two more redox processes (E_1/2, 1, −0.97, −1.09; 2, −1.06, −1.42 V) involving the coordinated dppt ligand are also observed. A plot of the difference between the metal oxidation and ligand reduction potentials of the complexes versus the absorption or emission maxima is linear, illustrating that the lowest π^∗ orbitals of dppt are involved in the redox, absorption and emission processes in the complexes. Electrochemical parameterisation of the Ru(II)/Ru(III) redox potentials of the present complexes has been carried out using Lever’s method and the calculated ligand reduction potential E_L(L) correlates well with the observed Ru(II)/Ru(III) redox potentials.     

Structure and Photosynthetic Mimicking of Bis(2,6-bis(benzimidazol-2-yl)pyridine)manganese(II)

Introduction　　Manganeseionsplayanimportantroleinthelight in ducedoxidationofwatertomolecularoxygeninphotosys temII (PSII)ofgreenplants.1 3Inrecentyears ,man ganesecomplexesofpolypyridineligands ,suchasbipyri dine ,1,10 phenanthrolineand 2 ,2′:6′,2″ terpyridine ,havehadconsiderableattentionasthecomplexesformedareusefulmodelsformanganese containingbimolecu lars .4 6 Therefore ,synthesisandcharacterizationofman ganeseinitsvariousoxidationstates ,withvariousligandtypesandnuclearities ,hav…     

微波作用下合成双(苯并咪唑-2-基)甲烷衍生物

在无溶剂、无催化剂存在条件下, 用微波促进5-取代-1H-苯并咪唑-2-乙酸乙酯和4-取代-1,2-邻苯二胺反应, 合成了取代双(苯并咪唑-2-基)甲烷衍生物, 产率均在80%以上. 产物结构经IR, ¹H NMR, MS等进行了表征.     

2,6-双(1-苄基-2-苯并咪唑基)吡啶的合成、晶体结构、光谱及抗氧化活性

合成了化合物2,6-双(1-苄基-2-苯并咪唑基)吡啶,通过元素分析、红外光谱、核磁共振氢谱和X-射线单晶衍射方法对其结构进行了表征.结构分析表明,该晶体属于单斜晶系,C2/c空间群,晶胞参数a=2.989 30(15) nm,b=1.093 74(5) nm,c=1.578 86(7) nm, β=103.555(5)o,V=5.018 32(42) nm3,Z=8,Dc=1.301 g/cm3,μ(Mo-Kα)=0.079 mm-1,F(000)=2 064,S=1.038,R1=0.046 0,w R2=0.127 9,化合物分子间存在的C—Hπ和苯环ππ堆积作用,使得其沿b轴方向形成了一维链状结构.通过紫外-可见吸收和荧光光谱研究了化合物的光谱性质及其对DPPH自由基的抗氧化活性.     

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.     

Synthesis,structure and electrochemical behaviour of cobalt(II) complexes with 2,6-bis(benzimidazol-2′-yl) pyridine

Summary The complexes Co(BBP)Cl₂, Co(BBP)₂SO₄·H₂O, Co(BBP)₂(NO₃)₂·H₂O, Co(BBP)₂(ClO₄)₂ and Co(BBP−H)₂· 2H₂O, where BBP is 2,6-bis(benzimidazol-2′-yl) pyridine, were prepared and characterized by elemental analysis, electrical conductance, i.r. and electronic spectra. The electrochemical behaviour of the complexes was recorded and the X-ray crystal structure of Co(BBP)Cl₂(MeOH)₂ was determined. The geometry about cobalt is a distorted octahedron.     

Synthesis and properties of poly(thioether amide)s from 2,6-bis(acrylamido)pyridine and dithiols

Poly(thioether amide)s containing pyridine moieties in their backbone were obtained by the polyaddition of 2,6-bis(acrylamido)pyridine (2,6-BAAP), derived from 2,6-diaminopyridine and acryloyl chloride, with an aromatic or aliphatic dithiol. The influence of various reaction conditions on the polyaddition was investigated in comparison with the polyaddition of 1,3-bis (acrylamido)benzene (1,3-BAAB). 2,6-BAAP gave the polymer even in the absence of any initiator at lower temperatures while 1,3-BAAB did not, which was attributable principally to intramolecular base catalysis of the pyridine moieties. Basic additives effectively promoted the reaction rate and increased the chain length. Those facts and NMR of the resulting polymers indicated Michael-type polyaddition. The polymers from 2,6-BAAP were amorphous and gave transparent and tough films having a high refractive index exceeding 1.7. GPC and DSC characterizations were also made. © 1993 John Wiley & Sons, Inc.     

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.     

Solvo-thermal Preparation and Characterization of Two CdII Coordination Polymers Constructed From 2,6-(1,2,4-Triazole-4-yl)pyridine and 5-R-Isophthalic Acid (R = Nitro,Sulfo)

Under the solvo-thermal conditions, two novel Cd^II mixed-ligand coordination materials with 2,6-(1,2,4-triazole-4-yl)pyridine(L₁) and aromatic poly-carboxylic acid co-ligands such as 5-R-isophthalic acid (R = nitro, sulfo), namely [Cd(L₁)(NO₂-BDC)(H₂O)₂] · 2H₂O ( 1 ) and [Cd(L₁)(HSIP)(H₂O)] · 4H₂O ( 2 ) (NO₂-H₂BDC = 5-nitroisophthalic acid, H₃SIP = 5-sulfobenzene -isophthalic acid) were successfully prepared. These Cd^II mixed-ligand coordination polymers 1 – 2 have been measured by crystal X-ray analysis, FT-IR spectra and powder X-ray diffraction analyses. In 1 , these seven-coordinate Cd^II atoms (Cd1) are inter-linked by didentate 5-nitroisophthalic acid ligands forming 1D chain structures. In 2 , these L₁ and partially de-pronated HSIP^2– are inter-linked by central Cd^II centers and are arranged into the unique 2D micro-porous metal-organic framework of 2 . Side view of 2 , it is noted that numerous oxygen atoms of un-coordinated carboxylate groups and coordinated SO₃ groups protrude out and decorate the 2D framework of 2 . PXRD patterns of 1 and 2 sample is tested, which is consistent with the simulated PXRD diffraction pattern. Photoluminescence studies show that 2 is highly selective and sensitive to trace elements of Eu³⁺ with excellent K_sv value (7.86 × 10⁴ m ^–1) and low detection limit (5.56 × 10^–2 mM), which also provides a convenient method and platform for real-time detection of Eu³⁺.     

Synthesis and spectral studies on heterobimetallic complexes of manganese and ruthenium derived from N-(2-hydroxynaphthalen-1-yl)methylenebenzoylhydrazide

The complex [Mn^IV(napbh)₂] (napbhH₂ = N-(2-hydroxynaphthalen-1-yl)methylenebenzoylhydrazide) reacts with activated ruthenium(III) chloride in methanol in 1 : 1.2 molar ratio under reflux, giving heterobimetallic complexes, [Mn^IV(napbh)₂Ru^IIICl₃(H₂O)] · [Ru^III(napbhH)Cl₂(H₂O)] reacts with Mn(OAc)₂·4H₂O in methanol in 1 : 1.2 molar ratio under reflux to give [Ru^III(napbhH)Cl₂(H₂O)Mn^II(OAc)₂]. Replacement of aquo in these heterobimetallic complexes has been observed when the reactions are carried out in the presence of pyridine (py), 3-picoline (3-pic), or 4-picoline (4-pic). The molar conductances for these complexes in DMF indicates 1 : 1 electrolytes. Magnetic moment values suggest that these heterobimetallic complexes contain Mn^IV and Ru^III or Ru^III and Mn^II in the same structural unit. Electronic spectral studies suggest six coordinate metal ions. IR spectra reveal that the napbhH₂ ligand coordinates in its enol form to Mn^IV and bridges to Ru^III and in the keto form to Ru^III and bridging to Mn^II.     

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,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.     

Study on synthesis and characterization of novel polyimides derived from 2,6-Bis(3-aminobenzoyl) pyridine

A new kind of aromatic diamine monomer containing pyridine unit, 2,6-Bis(3-aminobenzoyl)pyridine (BABP), was synthesized by the Friedel-Crafts acylation of benzene with 2,6-pyridinedicarbonyl chloride to form 2,6-Dibenzoylpyridine (DBPY), the nitrification of DBPY with nitric acid (99%) to form dinitro compound (BNBP), and the deoxidization of BNBP using SnCl₂in ethanol, successively. The diamine monomer BABP reacted with various aromatic dianhydrides to prepare a series of poly(amic acid), meanwhile, corresponding polyimides were obtained via the thermal or chemical imidzation procedures of the resulting poly(amic acid). The poly(amic acid) solutions in N,N-dimethyacetamide (DMAc) would be coated onto a plane-glass and could be thermally converted into transparent and tough polyimides films. The compositions, structures of the resulting monomer including corresponding intermediates, as well as the structure, physical property, thermostability, thermal behavior, solubility and solution viscosity of the resulting polyimides were characterized by means of FT-IR, ¹H-NMR, ¹³C-NMR, MS (EI), DSC, TGA, wide-angle X-ray diffraction, elemental analysis methods, and the effects of reactive conditions on the above structures and properties were studied, too.     

Synthesis of tridentate 2,6-bis(imino)pyridyl aminechlorohydro ruthenium(II) complexes: The convenient use of amine hydrochlorides to generate metal-hydride

The reaction of low-valent ruthenium complexes with 2,6-bis(imino)pyridine ligand, [η²-N₃]Ru(η⁶-Ar) (1) or {[N₃]Ru}₂(μ-N₂) (2) with amine hydrochlorides generates six-coordinate chlorohydro ruthenium (II) complexes with amine ligands, [N₃]Ru(H)(Cl)(amine) (4). Either complex 1 or 2 activates amine hydrochlorides 3, and the amines coordinate to the ruthenium center to give complex 4. This is a convenient and useful synthetic approach to form ruthenium complexes with amine and hydride ligands using amine hydrochloride.