Complexation and Electronic Spectra of Neodymium(III)–Amino Acid–1,10-Phenanthroline Systems in Aqueous Solution

Complexation of neodymium(III)-glutamate(glu)-phenanthroline(phen), neodymium(III)-aspartate(asp)-phenanthroline(phen) ternary systems and the corresponding binary systems in aqueous solution are discussed at various values of pH. Based on change regularity of hypersensitive transition intensities, the neodymium(III)-aspartate-phenanthroline ternary complex has a general formula of Nd(asp)₃phen, but the composition of the complex of Nd(III) with glutamate and phenanthroline is complicated and has not been determined. The electronic spectra of these complexes were studied, Slater-Condon parametersF _k ^s and the Lande parameter ξ_4f were obtained. The rms deviation between calculated and observed energy levels is less than 43 cm⁻¹. Bonding in these complexes are also investigated and bonding parameters calculated. The results show that Nd(III) and amino acids form complexes by ionic linkage with carboxylic oxygens, but with some weak covalency. Besides, the degrees of covalency in ternary complexes are larger than those in binary complexes.     

Use of SDS micelles to stabilize a ternary intermediate in the reaction of ferrioxamine B and 1,10-phenanthroline

Spectrophotometric measurements of the reaction of ferrioxamine B (FeHDFB(+)) with 1,10-phenanthroline (phen) reveal the presence of a ternary intermediate complex in both aqueous solution and an aqueous solution of 0.16 M sodium dodecyl sulfate (SDS). The stoichiometry of the intermediate is Fe(H(2)DFB)(phen)(2+) on the basis of a Schwarzenbach analysis of spectrophotometric data obtained at variable pH and phen concentrations. The ternary complex formation constant for the reaction FeHDFB(+) + H(+) + phen right arrow over left arrow Fe(H(2)DFB)(phen)(2+) is log K = 6.96 in aqueous solution and log K = 8.64 in aqueous 0.16 M SDS. The enhanced stability of Fe(H(2)DFB)(phen)(2+) in micellar solution was analyzed in terms of the pseudophase ion-exchange (PPIE) model of micellar reactions. The association constants for the binding of each reactant to the micellar pseudophase were measured by ultrafiltration. According to PPIE model calculations, the enhanced stability of Fe(H(2)DFB)(phen)(2+) in micellar SDS arises from a proximity effect created by the high local concentrations of reactants in the micellar pseudophase. The calculations also indicate that an inhibitory medium or compartmentalization effect is operative since the observed micellar enhancement is much smaller than predicted by the PPIE model. The micellar stabilization of the Fe(H(2)DFB)(phen)(2+) intermediate and the overall conversion of FeHDFB(+) to Fe(phen)(3)(2+) are discussed as a possible model system for siderophore iron release in microbial organisms.     

Luminescent iridium phenanthroline crown ether complex for the detection of silver(I) ions in aqueous media

The crown ether-linked iridium(III) complex [Ir(ppy)2 (di-aza-phen)]+ (1) {ppy = 2-phenylpyridine and di-aza-phen = 4,7-di(1,4-dioxa-7,13-dithia-10-azacyclopenta-dec-10-yl)-1,10-phenanthroline (7)} has been prepared. Compound 1 exhibits a notable luminescence enhancement in the presence of Ag+ in aqueous media. The analogous ruthenium(II) complex [Ru(phen)2(di-aza-phen)]2+ (4) {phen = 1,10-phenanthroline}, although equally exhibiting a luminescence enhancement in the presence of Ag+, is a far inferior sensor for Ag+ than 1. The 10 times higher luminescence enhancement (I - I0)/I0 of 1 was attributed to a dominance of the emission involving the di-aza-phen ligand that is responsible for binding to the metal ion. In contrast, the 3MLCT emission of 4 does not involve the di-aza-phen ligand but does involve the phen ligand, thus only allowing for a remote effect upon addition of Ag+ ions. While 1 is a highly selective chemosensor for Ag+ in the presence of many metal ions, there is a strong interference of Hg2+ that may restrict its practical use.     

Complexation of diazaperylene and bisisoquinoline with transition metal ions in the gas phase studied by electrospray ionization mass spectrometry

The complex formation of the ligands 1,12-diazaperylene (dap), 1,1'-bisisoquinoline (bis), 2,2'-bipyridine (bpy) and 1,10-phenanthroline (phen) with transition metal ions (M = Fe, Co, Ni, Cu, Zn, Ru, Os, Re, Pd, Pt, Ag and Cd) in the gas phase has been studied by electrospray ionization mass spectrometry. With the exception of Ru, Os, Fe, Ni and Cu, singly charged complexes [MLn](+) (n = 1,2) were observed. The complexes of dap and bis with Ru, Os, Fe and Ni ions, and the mixed ligand complexes with bpy and phen, are preferably of the doubly charged type [ML3]2+. In addition, collision-induced dissociation (CID) measurements were employed to evaluate the relative stabilities of these complexes. The CID experiments of mixed-ligand complexes which contain both dap and phen or dap and bpy exhibit preferential elimination of bpy, indicating that bpy is a weaker ligand than phen and dap.     

铕(Ⅲ)水杨酸邻菲咯啉三元配合物性质研究

合成了Eu3+的水杨酸和邻菲咯啉三元配合物,其组成为Eu(Hsal)3phen,用IR,UV,XPS研究配合物的性质和成键特征.结果表明,Hsal-的羧基、phen的两个氮原子均与Eu3+离子呈双齿配位,形成配合物后芳香环上的共轭性减小.用循环伏安法研究了配合物在玻碳电极上的电化学行为,发现配合物的电化学可逆性比游离Eu3+离子差,不同底液对配合物的电化学行为有影响.     

The effect of ligand donor atoms on ternary complex stability

Formation constants of mixed ligand complexes of Cu²⁺, Zn²⁺, Ni²⁺, Co²⁺, and Mn²⁺,with cyadine-5′-monophosphoric acid (CMP) and various primary ligands such as 1,10-phenanthroline(phen), glycylglycine(glygly) and salicylic acid (sal) have been determined in aqueous solution at 35°C and 0.1 M (KNO₃) by potentiomeric measurements. The acid dissociation constants of all the above mentioned ligands together with their 1 : 1 binary metal complex formation constants were also measured at 35°C. In general all the 1 : 1 binary complexes follow the Irving-Williams order of stability. Further the binary metal complexes of primary ligands are more stable than their ternary complexes with CMP. For ternary complexes, Δ(log K) values seem to change from positive to highly negative as the coordinating atoms of the primary ligands were varied from N,N to N,O^? to O^?O^?. The higher stability of ternary complexes involving phen is due to its Π-bonding interaction with the above metal ions and the relative decrease in the stability of other ternary systems is due to the coulombic repulsion of donor oxygen atoms of primary and secondary ligands. Thus for ternary complexes the stabilities follow a decreasing order of M-phen-CMP > M-glygly-CMP > M-sal-CMP.     

钴与吡啶-2,6-二甲酸和邻菲咯啉三元配合物的合成与晶体结构

合成了钴(Ⅱ)与吡啶-2,6-二甲酸和邻菲咯啉三元配合物Co(DPC)(phen)(H_2O)]·2H_2O(DPC=C7H3O4N;phen=C12H8N2·H_2O),并获得其单晶。晶体学数据如下：C19H17CoN3O7, Mr = 458.29,三斜晶系, P空间群。 a = 7.818(1), b = 9.290(2), c = 14.048(3) ?, α = 81.477(1), β = 81.456(8), γ = 72.970(2)°, V = 958.7(3) ?3, Z =2, F(000) = 470, Dc= 1.588Mg/m3, μ(MoKα) = 0.944mm-1。中心Co(Ⅱ)离子为6配位,6个配位原子形成一个畸变的八面体构型。     

铜与苯甲酸和邻菲咯啉三元配合物的合成与晶体结构

合成了铜 (Ⅱ )与苯甲酸和邻菲咯啉三元配合物 [Cu(ba) 2 (phen) (H2 O) ] (ba :苯甲酸 ;phen :1,10 邻菲咯啉 ) ,得到了它的单晶。用X射线衍射法测定了配合物的晶体结构。晶体学数据如下 :C52 H4 0 Cu2 N4 O10 ,Mr=10 0 7.96 ,单斜 ,P2 1/n ,a =10 .45 5 (1) ,b =2 1.2 6 3(2 ) ,c =11.199(2 ) ;β =117.6 90 (10 )°,Z =2 ,V =2 2 0 4.5 (5 ) 3,F(0 0 0 ) =10 36 ,Dc=1.5 19Mg/m3,μ =1.0 33mm- 1。晶体分子配位中心Cu(Ⅱ )离子的配位数为 5 ,这五个配位原子形成一个畸变的四方锥结构 ,配合物分子因分子间氢键作用以二聚体形式存在。     

Electrocarboxylation of chloroacetonitrile mediated by electrogenerated cobalt(I) phenanthroline

The electrocarboxylation of chloroacetonitrile mediated by [Co(II)(phen)₃]²⁺ has been investigated. Cyclic voltammetry studies of [Co(II)(phen)₃]²⁺ have shown that [Co(I)(phen)₃]⁺, an 18 electron complex, activates chloroacetonitrile by an oxidative addition through the loss of a phenanthroline ligand to give [RCo(III)(phen)₂Cl]⁺. The unstable one-electron-reduced complex underwent Co–C bond cleavage. In carbon dioxide saturated solution, CO₂ insertion proceeds after reduction of the alkylcobalt complex. A catalytic current is observed which corresponds to the electrocarboxylation of chloroacetonitrile into cyanoacetic acid. Electrolyses confirmed the process and gave faradic yield of 62% in cyanoacetic acid at potentials that are about 0.3 V less cathodic than the one required for Ni(salen).     

Flow Injection Spectrofluorimetric Determination of Terbium (III) Based on Solubilizing its Ternary Complex in Micellar Solution

Abstract

A flow injection spectrofluorimetric method has been developed for the determination of terbium (III) based on solubilizing its ternary complex with pi valoyitrifluoroacetone (PTA) and trioctylphosphine oxide(TOPO) in micellar solution of nona (oxyethylene) dodecyl ether (BL-9EX). Accuracy and reproducibility are good up to 16 ng/ml of terbium (III) and 80 samples per hour can be analyzed. The relative standard deviation was less than 1.0 %. No interferences from 20-fold excesses of 11 rare earth ions were observed.     

Sensing of molecular chirality on an electrode modified with a clay-metal complex hybrid film

A chiral sensing electrode has been prepared by coating an indium tin oxide (ITO) substrate with a hybrid film of metal complexes and a clay layer (montmorillonite). By applying the combined method of the Langmuir-Blodgett and self-assembly techniques, a monolayer of a water-soluble chiral metal complex (Lambda-[Os(phen)(3)](2+)), which acted as a mediator of oxidizing a target molecule, was fixed electrostatically onto a single-layered clay film. Chiral sensing was demonstrated by monitoring a photocurrent when the electrode was in contact with an aqueous NaClO(4) solution of 1,1'-2-binaphthol. As a result, the S-1,1'-2-binaphthol gave a photocurrent 1.8 times higher than the R-isomer at the applied potential of 700 mV (vs Ag|AgCl|KCl(sat)). Detection limit was determined to be 40 microM from the concentration dependence of a response current. Mechanisms for chiral sensing effect were explained in terms of the stereoselective binding of 1,1'-2-binaphthol with adsorbed Lambda-[Os(phen)(3)](2+) on a clay surface.     

Studies on kinetics of complexation of lanthanide α-hydroxycarboxylates with 1,10-phenanthroline

Kinetics of the coordination reaction of lanthanide (La^III, Eu^III) α-hydroxycarboxylates [LnL₃(H₂O)₂] with 1,10-phenanthroline (phen) in methanol-water (v/v, 3:2) were studied at 25°C by calorimetric titration. A one-step reaction process in accordance with the rate law has been suggested. The reaction is found to be first order for both lanthanide α-hydroxycarboxylates and phen. We have evaluated rate constants of the reactions. It is found that a linear free energy relationship exists between the stability constants of the lanthanide-α-hydroxycarboxylate-phen ternary complex and the rate constants. It is also found that a linear free energy relationship exists between the rate constants of La-hydroxycarboxylate with phen and the acid strength of α-hydroxy-acid as primary ligand, but the linear free energy relationship does not exist in the Eu-α-hydroxycarboxylate-phen ternary complex. The influence of other factors upon the reaction rate constants was also discussed.     

X-ray structure characterization of palladium(II) ternary complexes of pyridinedicarboxylic and phthalic acid with phenanthroline and bipyridine

The crystal structures of the series of four ternary complexes, [Pd(phen)(2,6-PDCA)].4H(2)O (1) (phen=1,10-phenanthroline; 2,6-PDCA=2,6-pyridinedicarboxylic acid), [Pd(bpy)(2,3-PDCA)].3H(2)O (2) (bpy=2,2'-bipyridineand; 2,3-PDCA=2,3-pyridinedicarboxylic acid) and [Pd(phen)(PHT)].2.5H(2)O (3) (PHT=o-phthalic acid ) and [Pd(bpy)(PHT)].1.5H(2)O (4), are determined and the coordination modes of palladium(II) ternary complexes are characterized. All complexes take the mononuclear Pd(II) complexes, in which central Pd(II) atom of each complex has a similar distorted square-planar four coordination geometry. In all complexes, the aromatic heterocyclic compounds, phen and bpy, behave as a bidentate N, N' ligand. In the complex 1 and 2, 2,6-PDCA and 2,3-PDCA behave as a bidentate N, O ligand, and in complex 3 and 4, PHT behaves as a bidentate O, O' ligand.     

Synthesis,DNA-binding,cytotoxicity, and cleavage studies of unsymmetrical oxovanadium complexes

An unsymmetrical oxovanadium complex [VO(SAA)(phen)] (1) (SAA?=?salicylidene anthranilic acid, phen?=?phenanthroline) and its derivative [VO(MOSAA)(phen)] (2) (MOSAA?=?2-hydroxy-4-methoxysalicylidene anthranilic) have been synthesized and characterized by elemental analysis, UV-Vis, ES-MS, IR, and ¹H NMR. The interaction of these two complexes with calf thymus DNA (CT-DNA) was investigated by absorption titration, fluorescence spectra, viscosity measurements, and thermal denaturation. Their photocleavage reactions with pBR322 supercoiled plasmid DNA were investigated by gel electrophoresis. The cytotoxicity of these two complexes against myeloma cell (Ag8.653) and gliomas cell (U251) have been assessed by MTT assay. The results show that both 1 and 2 bind to CT-DNA in classical intercalation, and the DNA-binding affinity of 1 is larger than that of 2. These complexes enhance the oxidative cleavage of supercoiled pBR322 DNA and both complexes have cytotoxic activities against Ag8.653 and U251 cell lines. Complex 1 has more potent inhibitory effect against the two cell lines than 2.     

Ternary copper complexes for photocleavage of DNA by red light: direct evidence for sulfur-to-copper charge transfer and d-d band involvement

A new class of ternary copper(II) complexes of formulation [Cu(L(n)B](ClO(4)) (1-4), where HL(n) is a NSO-donor Schiff base (HL(1), HL(2)) and B is a NN-donor heterocyclic base viz. 1,10-phenanthroline (phen) and 2,9-dimethyl-1,10-phenanthroline (dmp), are prepared, structurally characterized, and their DNA binding and photocleavage activities studied in the presence of red light. Ternary complex [Cu(L(3))(phen)](ClO(4)) (5) containing an ONO-donor Schiff base and a binary complex [Cu(L(2))(2)] (6) are also prepared and structurally characterized for mechanistic investigations of the DNA cleavage reactions. While 1-4 have a square pyramidal (4 + 1) CuN(3)OS coordination geometry with the Schiff base bonded at the equatorial sites, 5 has a square pyramidal (4 + 1) geometry with CuN(3)O(2) coordination with the alcoholic oxygen at the axial site, and 6 has a square planar trans-CuN(2)O(2) geometry. Binding of the complexes 1-4 to calf thymus DNA shows the relative order: phen > dmp. Mechanistic investigations using distamycin reveal minor groove binding for the complexes. The phen complexes containing the Schiff base with a thiomethyl or thiophenyl moiety show red light induced photocleavage. The dmp complexes are essentially photonuclease inactive. Complexes 5 and 6 are cleavage inactive under similar photolytic conditions. A 10 microM solution of 1 displays a 72% cleavage of SC DNA (0.5 microg) on an exposure of 30 min using a 603 nm Nd:YAG pulsed laser (60 mJ/P) in Tris-HCl buffer (pH 7.2). Significant cleavage of 1 is also observed at 694 nm using a Ruby laser. Complex 1 is cleavage inactive under argon or nitrogen atmosphere. It shows a more enhanced cleavage in pure oxygen than in air. Enhancement of cleavage in D(2)O and inhibition with sodium azide addition indicate the possibility of the formation of singlet oxygen as a reactive intermediate leading to DNA cleavage. The d-d band excitation with red light shows significant enhancement of cleavage yield. The results indicate that the phen ligand is necessary for DNA binding of the complex. Both the sulfur-to-copper charge transfer band and copper d-d band excitations helped the DNA cleavage. While the absorption of a red photon induces a metal d-d transition, excitation at shorter visible wavelengths leads to the sulfur-to-copper charge transfer band excitation at the initial step of photocleavage. The excitation energy is subsequently transferred to ground state oxygen molecules to produce singlet oxygen that cleaves the DNA.     

Synthesis and spectroelectrochemistry of Ir(bpy)(phen)(phi)(3+), a tris(heteroleptic) metallointercalator

A tris(heteroleptic) phenanthrenequinone diimine (phi) complex of Ir(III), Ir(bpy)(phen)(phi)(3+), was synthesized through the stepwise introduction of three different bidentate ligands, and the Lambda- and Delta-enantiomers were resolved and characterized by CD spectroscopy. Like other phi complexes, this tris(heteroleptic) iridium complex binds avidly to DNA by intercalation. Electrochemical studies show that Ir(bpy)(phen)(phi)(3+) undergoes a reversible one-electron reduction at E(0) = -0.025 V in 0.1 M TBAH/DMF (versus Ag/AgCl), and spectroelectrochemical studies indicate that this reduction is centered on the phi ligand. The EPR spectrum of electrochemically generated Ir(bpy)(phen)(phi)(2+) is consistent with a phi-based radical. The electrochemistry of Ir(bpy)(phen)(phi)(3+) was also probed at a DNA-modified electrode, where a DNA binding affinity of K = 1.1 x 10(6) M(-1) was measured. In contrast to Ir(bpy)(phen)(phi)(3+) free in solution, the complex bound to DNA undergoes a concerted two-electron reduction, to form a diradical species. On the basis of UV-visible and EPR spectroscopies, it is found that disproportionation of electrochemically generated Ir(bpy)(phen)(phi)(2+) occurs upon DNA binding. These results underscore the rich redox chemistry associated with metallointercalators bound to DNA.     

Investigations of ternary complexes of Co(II) and Ni(II) with oxydiacetate anion and 1,10-phenanthroline or 2,2′-bipyridine in solutions

Potentiometric (PT) and conductometric (CT) titration methods have been used to determine the stoichiometry and formation constants in water for a series of ternary complexes of Co(II) and Ni(II) involving the oxydiacetate anion (ODA) and 1,10-phenanthroline (phen) or 2,2′-bipyridine (bipy) ligands, namely [Co(ODA)(phen)(H₂O)], [Co(ODA)(bpy)(H₂O)], [Ni(ODA)(phen)(H₂O)] and [Ni(ODA)(bpy)(H₂O)]. The ternary complex formation process was found to take place in a stepwise manner in which the oxydiacetate ligand acts as a primary ligand and the phen or bipy ligands act as auxiliary ones. The stability of the ternary complexes formed is discussed in the relation to the corresponding binary ones. Furthermore, the kinetics of the substitution reactions of the aqua ligands in the coordination sphere of the Ni-ODA and Co-ODA complexes to phen or bipy were studied by the stopped-flow method. The kinetic measurements were performed in the 288–303 K temperature range, at a constant concentration of phen or bipy and at seven different concentrations of the binary complexes (4–7 mM). The influence of experimental conditions and the kind of the auxiliary ligands (phen/bipy) on the substitution rate was discussed.      

Synthesis of a Ag-bridged V-centred tungstovanadate dimer capped by [Ag(phen)] units

A Ag-bridged V-centred tungstovanadate dimer capped by [Ag(phen)] unit, [Ag(phen)₂]₇{Ag[Ag(phen)(VW₁₀V₂O₄₀)]₂} (1) (phen = 1,10-phenanthroline), has been hydrothermally synthesized, and characterized by IR, TG and single-crystal X-ray diffraction. Structural analysis reveals that the compound is composed of one dimeric {Ag[Ag(phen)(VW₁₀V₂O₄₀)]₂}^7? anion and seven [Ag(phen)₂]⁺ cations, which represents the first V-centred tungstovanadate grafted by transition metal coordination polymers. Furthermore, the electrochemical properties of 1 have been studied in the paper.     

胶束介质在速差动力学分析中的应用: 钴、镍的同时测定

研究溴化十六烷基三甲铵表面活性剂对钴(Ⅱ)、镍(Ⅱ)与二甲酚橙配位反应的影响, 测定了反应级数和表观活化能。由于胶束介质的存在, 钴(Ⅱ)、镍(Ⅱ)三元配合物的灵敏度比二元配合物分别提高了4.4和8.6倍, 并扩大了两组分的速率差别, 改善了反应的选择性。基于两组分反应速率的差别, 采用对数外推法计算机处理数据, 建立了速差动力学同时测定钴(Ⅱ)、镍(Ⅱ)的新方法。应用于钴精矿等几种实际样品中钴、镍的同时测定获得了满意结果, 其相对误差和标准偏差分别在4%和3%以内。     

[Cu（L-Ⅱe）（Phen）（H2O）（ClO4）]的合成、结构及稳定性研究

合成了三元混配配合物[Cu(L-Ile)(Phen)(H_2O)(ClO_4)](L-Ile=L=异亮氨酸,phen=1,10-邻菲咯啉),通过红外光谱、紫外-可见光谱、摩尔电导率、X射线单晶结构分析,对配合物进行了表征。该晶体属单斜晶系,P2_1空间群,晶胞参数:a=1.1704(5)nm,b=0.8090(5)nm,c=2.1822(5)nm,β=98.061(5)°,Z=2,D_x=1.60Mg·m~(-3),R_1=0.0462,wR_2=0.1225。每个配合物分子中Cu(Ⅱ)离子与一个L-Ile(N,O)配体、一个Phen(N,N)配体、一个H_2O(O)配体及一个Cl_O~-(O)形成六配位的畸变八面体构型。本文还用电位滴定法测定了配合物的稳定常数,结果表明,配合物具有高的稳定性。