IR luminescence of neodymium(III) and ytterbium(III) complexes with acylpyrazolones in solutions

Acylpyrazolones (L1–L5) have been synthesized and the conditions of their complexation with neodymium(III) and ytterbium(III) ions in aqueous solutions have been elucidated. The component ratio in the synthesized complexes is Nd(Yb): L = 1: 1. The conditions of excitation and luminescence of the ligands and complexes have been studied. The formation of mixed-ligand complexes upon the introduction of trioctyl- or triphenylphosphine oxide leads to a considerable rise of neodymium and ytterbium. In the presence of 1,10-phenanthroline and bathophenanthroline, competing complexation leads to a 20–70% decrease in luminescence intensity. The introduction of water-miscible organic solvents (30 vol %) decreases the Nd(III) and Yb(III) luminescence intensity by a factor of 9–20.     

Preconcentration of molybdenum(VI) on polymeric adsorbents and its photometric determination with bis(2,3,4-trihydroxyphenylazo)benzidine in the presence of 1,10-phenanthroline

The complexation of molybdenum(VI) with bis(2,3,4-trihydroxyphenylazo)benzidine (H₆L) is studied in the presence of 1,10-phenanthroline. A mixed-ligand complex formed with a molar component ratio of 2: 2: 4. The maximum absorbances of the binary and mixed-ligand complexes are observed at 437 and 426 nm, and their molar absorbance coefficients are (9.02 ± 0.02) × 10⁴ and (10.01 ± 0.01) × 10⁴, respectively. It is found that 1,10-phenanthroline affects H₆L and improves the complexation characteristics. A procedure is developed for the photometric determination of molybdenum(VI) in seawater after preconcentration.     

Complex compounds of terbium(III) with some nonsteroidal anti-inflammatory drugs and their analytical applications

Luminescence properties of the complexes of terbium(III) with nonsteroidal anti-inflammatory drugs (ibuprofen and orthofen) were studied. It was demonstrated that in the presence of organic bases (2,2’-dipyridyl and 1,10-phenanthroline) mixed-ligand complexes are formed and the luminescence intensity of terbium(III) increases by a factor of up to 250. The optimum complexation conditions were determined. It was proposed to use these complexes as analytical forms for the luminescence determination of nonsteroidal anti-inflammatory drugs (ibuprofen and orthofen) in pharmaceutical dosage forms. The detection limits are 2 and 0.05 μg/mL, respectively.     

Effect of heterocyclic diimine ligands with donor and acceptor substituents on the spectroscopic and electrochemical properties of Au(III) complexes

The composition, structure, and properties of a series of Au(III) complexes with heterocyclic diimine ligands [Au(N^N)Cl₂]⁺, where (N^N) = 2,2′-bipyridine (Bipy), 4,4′-dimethyl-2,2′-bipyridine (DmBipy), 2,2′-biquinoline (Bqx), 1,10-phenanthroline (Phen), 2,9-dimethyl-1,10-phenanthroline (DmPhen), and 4,7-diphenyl-1,10-phenanthroline (DphPhen), were characterized by ¹H NMR, electronic absorption, and emission spectroscopy and also by cyclic voltammetry. The influence of donor and acceptor substituents on the spectroscopic and electrochemical properties of the Au(III) complexes was revealed.     

Etude du pouvoir inhibiteur de la 2,9-chlorométhyl-1,10-phénanthroline pour la corrosion d'un acier doux en milieu HCL 1M A 90 °C

The corrosion behaviour of mild steel in 1M HCl containing organic compounds such as: 2,2′-bipyridine (inh1), 1,10-phenanthroline (inh2), 4,4′-6,6′-tetramethyl-2,2′-bipyridine (inh3) and 2,9-chloromethyl-1,10-phenanthroline (inh4), was studied by weight loss and electrochemical polarization methods. Polarization data indicate that all tested compounds are mixed-type inhibitors affecting both cathodic and anodic processes. The inhibition efficiency of these additives increases in the order: inh3 < inh1 < inh2 < inh4. The adsorption of 2,9-chloromethyl-1,10-phenanthroline on the mild steel surface in 1M HCl medium follows a Langmuir adsorption isotherm. The effect of temperature indicates that the inhibition efficiency of inh4 is temperature independent in the range 25 to 90 °C. The apparent activation energies in the absence and in the presence of inh4 were determined.     

Kinetics and mechanism of chromium(III) catalyzed oxidation of 1,10-phenanthroline by alkaline permanganate

The kinetics of chromium(III) catalyzed oxidation of 1,10-phenanthroline by permanganate in alkaline medium at a constant ionic strength has been studied spectrophotometrically. The reaction between permanganate and 1,10-phenanthroline in alkaline medium exhibits 4:1 stoichiometry (KMnO₄:1,10-phenanthroline). The reaction shows first order dependence on [permanganate] and [chromium(III)] and less than unit order dependence in 1,10-phenanthroline, zero order in alkali concentrations. The results suggest the formation of a complex between the 1,10-phenanthroline and the chromium(III) which reacts further with one mole of permanganate species in the rate-determining step, resulting in the formation of a free radical, which again reacts with three moles of permangante species in a subsequent fast step to yield the products. The reaction constants involved in the mechanism were evaluated. The activation parameters were computed with respect to the slow step of the mechanism.This revised version was published online in December 2005 with corrections to the Cover Date.     

New colorimetric detection of glucose by means of electron-accepting indicators: ligand substitution of [Fe(acac)3-n(phen)n]n+ complexes triggered by electron transfer from glucose oxidase

A new colorimetric detection technique for glucose, based on electron transfer from glucose oxidase (GODred) to iron(III) acetylacetonate(acac)/phenanthroline(phen) mixed complexes, is developed. When GOD is added to an aqueous mixture that contains tris(acetylacetonato)iron(III) complex (FeIII-(acac)3), 1,10-phenanthroline (phen), and glucose, the color immediately changes from pale yellow to red. The red color originates from formation of tris(1,10-phenanthroline)iron(II) complex ([FeII(phen)3]2+). Differential pulse voltammetry indicates that cationic, mixed-ligand complexes of [Fe(acac)3-n-(phen)n]n+ are formed upon mixing the labile FeIII(acac)3 complex and phenanthroline. The cationic mixed-ligand complexes electrostatically bind to GOD (pI 4.2), and are easily reduced by electron transfer from GODred. This electron transfer is not affected by the presence of oxygen. The reduced complex [FeII(acac)3-n(phen)n](n-1)+ then undergoes rapid ligand exchange to FeII (phen)3. Formation of the colored FeII complex is repressed when the salt concentration in the mixture is increased, or when anionic bathophenanthroline disulfonate (BPS) is employed in place of phenanthroline. The use of labile metal complexes as electron acceptors would be widely applicable to the design of new biochromic detection systems.     

Luminescence determination of praseodymium in solutions of its β-diketonates

With the aim of a search for new analytical forms for the determination of praseodymium(III), its 4f luminescence was studied in solutions of mixed-ligand complexes with fluorinated β-diketones and donoractive ligands (1,10-phenanthroline, neocuproine, diantipyrylmethane, diantipyrylpropylmethane, and trioctylphosphine oxide). It was found that the luminescence intensity of praseodymium(III) depends on both the character of the fluoroalkyl substituent in the β-diketone molecule and the nature of the second ligand. The complex of praseodymium(III) with thenoyltrifluoroacetone and diantipyrylpropylmethane was used for the determination of praseodymium in some optical materials. The lower determination limit of praseodymium was 0.01 μg/mL.     

Ca(Ⅱ)-NTP-HRB混配物的稳定性和配体堆积作用研究

The stability constants of the ternary mixed-ligand complexes of Ca(NTP)(HRB) n-(n=2 or 3) have been determined by potentiometric pH titration in aqueous solution (I=0.1mol/L,KNO3,25℃),Where NTP refers to adenosine 5′-triphorphat e (ATP) and uridine 5′-triphoophate (UTP);HRB,1,10-phenanthroline (Phen),2,2 ′-bipyridyl (Bpy),and L-tryptophan (Trp).The stability difference between the ternany complexes and the binary complexes has been compared and discussed.The increased stability in ternany mixed-ligand complexes was attributed to the coo perative effect of πA-πB and the intramolcular ligand-ligand aromatic st acking interaction.The extent of the stacking interaction in the ternary calcium compl exes was calculated,which is in accordance with the size of the aromatic rings f orming the stacks.     

Rhodium and platinum complexes as catalysts for the polymerization of phenylacetylene

In polymerization reactions of phenylacetylene three different types of polyphenylacetylene (PPA) were prepared by using Rh and Pt complexes as catalysts in different reaction conditions. Type I PPA is obtained with [Rh (COD) Chel] PF₆ complexes (COD = cis,cis-cycloocta 1,5-diene; chel = 2,2′-bipyridine, 1,10-phenanthroline, 2,9-dimethyl-1,10-phenanthroline, 5,6-dimethyl-1,10-phenanthroline, 3,4,7,8-tetramethyl-1,10-phenanthroline) in bulk, benzene methanol, while type II PPA is obtained with the same catalysts in p-dioxane and type III PPA in the presence of [Pt (? C?CPh)₂(PPh₃)₂] in bulk. Type I, II, and III PPA exhibit different IR and ¹H-NMR spectra, which have been compared with literature data. Correlations proposed by different Authors between spectral properties of PPA and chain structures are also discussed.     

Hexacyanoferrate(III) as a mediator in the determination of total iron in potable waters as iron(II)-1,10-phenanthroline at a single-use screen-printed carbon sensor device

Hexacyanoferrate(III) was used as a mediator in the determination of total iron, as iron(II)-1,10-phenanthroline, at a screen-printed carbon sensor device. Pre-reduction of iron(III) at −0.2 V versus Ag/AgCl (1 M KCl) in the presence of hexacyanoferrate(II) and 1,10-phenanthroline (pH 3.5-4.5), to iron(II)-1,10-phenanthroline, was complete at the unmodified carbon electrode surface. Total iron was then determined voltammetrically by oxidation of the iron(II)-1,10-phenanthroline at +0.82 V, with a detection limit of 10 μg l⁻¹.In potable waters, iron is present in hydrolysed form, and it was found necessary to change the pH to 2.5-2.7 in order to reduce the iron(III) within 30 s. A voltammetric response was not found at lower pH values owing to the non-formation of the iron(II)-1,10-phenanthroline complex below pH 2.5.Attempts to incorporate all the relevant reagents (1,10-phenanthroline, potassium hexacyanoferrate(III), potassium hydrogen sulphate, sodium acetate, and potassium chloride) into a modifying coated PVA film were partially successful. The coated electrode behaved very satisfactorily with freshly-prepared iron(II) and iron(III) solutions but with hydrolysed iron, the iron(III) signal was only 85% that of iron(II).     

三元混配铂(Ⅱ)配合物的稳定性和分子内芳环堆积效应研究

用pH电位滴定法测定了铂(Ⅱ)与核苷酸NTP (NTP为腺苷5′-三磷酸和尿苷5′-三磷酸)和另一芳环系列配体ArL形成的三元混配配合物Pt(ArL)(NTP)n-(ArL=Phen, Bpy和Trp; n=2或3)在水溶液中的稳定常数(I=0.1 mol/L, KNO3; 25℃).用ΔlogKPt比较了二元和三元混配配合物的稳定性差异,认为三元混配配合物稳定性的增加可归因于π-酸与π-碱之间的合作效应和分子内芳环配体的堆积作用.     

517—π-Acid effect on electrode behaviour of ternary complexes in solution: Complex formation between copper(II)-1,10-phenanthroline complex and ligands containing oxygen and/or nitrogen donor atoms as secondary ligands. Part I

The mixed-ligand complexes, [Cu_x,(phen)_yL_z] (where phen stands for 1,10-phenanthroline and L for some aliphatic acids, aromatic acids, amino acids, phenols and ethylenediamine in the ratio 1 : 1 : 1 and 1 : 2 : 1) undergo two-step, diffusion-controlled, irreversible electro-reduction in 0.5 M KNO₃ at the dropping mercury electrode. The double-wave nature of these complexes may be attributed to the adsorption effect of 1,10-phenanthroline. From the characteristics of the irreversible wave, the rate constant k_f, for each complex has been calculated at its formal potential. The driving force for the formation of ternary systems has been analysed. The parent complex, [Cu(phen)] is found to show a discriminating nature towards the incoming secondary ligand. Additional stability effects compared to such systems with 2,2′-bipyridyl as the parent ligand have been explained on the basis of comparatively greater π-effects of 1,10-phenanthroline. Such effects are found t o become more pronounced, due to the cooperative effect, if the secondary ligand also has a π-system.     

Phenanthroline complexes bearing fused dipyrrolylquinoxaline anion recognition sites: efficient fluoride anion receptors

Novel anion recognition host molecules, tris-1,10-phenanthroline cobalt(III) and bis-2,2'-bipyridine mono-1,10-phenanthroline ruthenium(II) complexes bearing fused dipyrrolylquinoxaline moieties have been synthesized. As determined by UV-vis spectroscopic and electrochemical studies, these metal complexes bind fluoride with high affinity in polar media both in absolute terms and relative to the metal-free phenanthroline dipyrrolylquinozaline precursor from which they are derived (fluoride is bound to the tris-1,10-phenanthroline cobalt(III) dipyrrolylquinoxaline system with a 1:1 binding constant of 54 000 M-1 in DMSO). The large observed binding constants are ascribed to two factors, (i) the presence of a phenanthroline-coordinated cationic charge that decreases the electron density on the pyrrole NH protons and (ii) pure electrostatic effects.     

Iron(II) and nickel(II) mixed-ligand complexes containing 1,10-phenanthroline and 4,7-diphenyl-1,10-phenanthroline

Two types of mixed-ligand complexes, i.e. [M(phen)2 (dip)]2+ and [M(phen)(dip)2]2+ (M = iron(II) and nickel(II); phen = 1,10-phenanthroline and dip = 4,7-diphenyl-1,10-phenanthroline) have been prepared from their related tris-complexes, [M(phen)3]2+ by ligand substitution, and isolated by semi-preparative HPLC. Elemental and chromatographic analyses confirm the purity of the isolated complexes while u.v./vis and i.r. spectra were used to identify and characterize them. 1H-n.m.r. and room temperature Mössbauer spectra of the iron(III) complexes were also measured and the results are discussed. In addition, our preliminary results on hypochromicity in the MLCT band and circular dihroism (CD) emerging in the u.v./vis region upon addition of CT(calf thymus)-DNA to the racemic complexes indicated that the iron(II) mixed-ligand complexes interact with CT-DNA.     

Kinetics and mechanism of the reduction of 1,10-phenanthroline—copper(II) complex

The cyclic voltammetric study of 1,10-phenanthroline—copper(II) complex was carried out in acidic buffer solution. It was found from the current—mole ratio (copper (II): 1,10-phenanthroline) relationship that the maximum coordination number of 1,10-phenanthroline—copper(II) complex was four under the present experimental condition. The reduction mechanism and kinetics of copper(II) was studied in the presence of various concentrations of 1,10-phenanthroline.     

Sorption–Spectrophotometric and Test Determination of Zinc(II) as the Mixed-Ligand Complex of 1,10-Phenanthroline and Bromophenol Blue

The interaction of Zn(II), Cd(II), and Pb(II) with 1,10-phenanthroline noncovalently immobilized on silica in the presence of Bromophenol Blue was studied. The optimum conditions of the reaction and the composition of mixed-ligand complexes that are formed at the surface were found, and a scheme was proposed for the interaction at the interface. A sorption–spectrophotometric procedure and a test scale were developed for the determination of zinc with detection limits of 0.011 and 0.018 mg/L, respectively. The procedure was used for the determination of labile zinc species in soil.     

Sorption-spectrophotometric determination of iron(II, III) with the use of organic reagents immobilized in a polymethacrylate matrix

The interaction of iron(II) with 2,2′-dipyridyl and 1,10-phenanthroline immobilized in a polymethacrylate matrix was studied. The optimum conditions of the complexation of iron(II) with the immobilized reagents and the chemical analytical properties of the complexes in the polymethacrylate matrix were determined. A sorption-spectrophotometric procedure was developed for the determination of iron(II) and the total of iron(II, III) after the reduction of iron(III) by ascorbic acid. The procedure with 2,2′-dipyridyl was used for the analysis of samples of tap, well, and mineral water and a solution of glucose.     

Mixed-ligand complex formation in the copper(I)-2,9-dimethyl-1,10-phenanthroline-3,3′-bonded biquinoline system according to <Superscript>1</Superscript>H NMR data

The reaction of the copper(I) 2,9-dimethyl-1,10-phenanthroline (neocuproine, DMP) complex with 2,3,8,9-dibenzo-4,7-dimethyl-5,6-dihydro-1,10-phenanthroline (cuprotest, DMQ) in a CD₃OD solution has been studied by ¹H NMR spectroscopy. The substitution of DMQ for the DMP liqand in the inner coordination sphere of the Cu⁺ complex has been observed. A model of the process including the formation of a mixed-ligand complex, presumably of bridged structure, is proposed to describe the observed experimental dependences of integrated intensities of the NMR signals in the spectrum on the concentrations of the components of the solution.     

Complex formation of rare-earth elements with 1,10-phenanthroline

Complex formation in a Ln(III)-1,10-phenanthroline-ethyl acetate system, where Ln = La, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, or Lu, is studied by spectrophotometric methods. The stability of the complexes is estimated. The changes in the thermodynamic parameters of complex formation and the bonding character in the lanthanide complexes with 1,10-phenanthroline and 2,2′-dipyridyl are ascertained and compared.