Electrogenerated chemiluminescence of Pb(II)-bromide complexes

The electrochemistry and electrogenerated chemiluminescence (ECL) of Pb₄Br₁₁ ³⁻ in acetonitrile solution is reported. Pb₄Br₁₁ ³⁻ is formed in situ by the reaction of lead(II) and bromide ions with ECL generated upon sweep to positive potentials using tri-n-propylamine (TPrA) as an oxidative-reductive coreactant. An ECL efficiency (φ_ecl) of 0.0079 was obtained compared to Ir(ppy)₃ (ppy=2-phenylpyridine; φ_ecl=1). The ECL intensity peaks at a potential corresponding to oxidation of TPrA and Pb₄Br₁₁ ³⁻ indicating that emission is from the lead-bromide cluster.     

Electrogenerated chemiluminescence of (bis-bipyridyl)ruthenium(II) acetylacetonate complexes

The synthesis, electrochemistry, spectroscopy and electrogenerated chemiluminescence (ECL) of five bis-bipyridine ruthenium(II) complexes containing acetylacetonate complexes are reported. More specifically, (bpy)₂Ru(BA)₂(PF₆) (bpy = 2,2′-bipyridine; BA = benzoylacetonate), (bpy)₂Ru(TTFA)(PF₆) (TTFA =  thenoyltrifluoroacetonate), (bpy)₂Ru(TFPB)(PF₆) (TFPB = 4,4,4-trifluoro-1-phenyl-1,3-butanedionate), (bpy)₂Ru(TFPD)(PF₆) (TFPD =  1,1,1-trifluoro-2-4-pentanedionate), and (bpy)₂Ru(DBM)(PF₆) (DBM = dibenzoylmethide) display UV-Vis, photoluminescence, electrochemical and ECL properties characteristic of ruthenium bipyridyl complexes. All complexes display absorptions in the UV and visible regions of the spectra, with visible absorptions ranging from 350 to 700 nm, typical of metal-to-ligand charge transfer (MLCT) transitions. Photoluminescence emission maxima are also characteristic of MLCT transitions with wavelength maxima from 575 to 600 nm depending on the nature of the acetylacetonate ligand. ECL efficiencies for the complexes (?_ecl ∼ 0.013-0.051) are much lower than a standard (?_ecl = 1) with electron-withdrawing substituents resulting in lower efficiencies.     

Electrogenerated chemiluminescence from osmium(II) polypyridine carbonyl chloride systems

The spectroscopy, electrochemistry and electrogenerated chemiluminescence (ECL) of four osmium(II) phenanthroline carbonyl chloride complexes are reported. Three of these compounds also contain diphosphine chelating ligands. ECL is generated in acetonitrile solutions with tri-n-propylamine (TPrA) as an oxidative-reductive coreactant. ECL efficiencies (?_ecl = photons emitted per redox event) between 0.011 and 0.13 were obtained in air saturated and deoxygenated solutions with Ru(bpy)₃²⁺ (bpy = 2,2′-bipyridine) as a relative standard (?_ecl = 1). The ECL intensity peaks at a potential corresponding to oxidation of both TPrA and the osmium systems, while ECL spectra (obtained using absorption filters) are similar to photoluminescence spectra, indicating that emission is from the excited states of the osmium complexes.     

Electrogenerated chemiluminescence properties of bisalicylideneethylenediamino (salen) metal complexes

The spectroscopy, electrochemistry and electrogenerated chemiluminescence (ECL) of eight bisalicylideneethylenediamino (salen) metal complexes are reported. Two of the complexes contain an unsubstituted salen ligand and either cobalt(II) or nickel(II). The others have 1,2-cyclohexanediamonio-N,N′-bis(3,5-di-t-butylsalicylidene) as the ligand, and chromium(III), aluminum(III), cobalt(II), cobalt(III) or manganese(II) as the metal center. The complexes have lowest energy absorption maxima between 350 and 430 nm. When excited at these wavelengths, the complexes emit between 417 and 594 nm in acetonitrile. Photoluminescence efficiencies (?_em) were between 0.0310 and 23.8 compared to Ru(bpy)₃²⁺ (bpy = 2,2′-bipyridine; ?_em = 1), with the aluminum complexes displaying the most intense photoluminescence. Both reversible and irreversible oxidative electrochemistry is displayed by the metal–salen complexes with oxidation potentials ranging between +0.152 and +1.661 V versus Ag/AgCl. The ECL intensity peaks at a potential corresponding to oxidation of both TPrA and the salen systems, indicating that both are involved in the ECL reaction sequence. ECL efficiencies (?_ecl) were between 0.0018 and 0.0086 when compared to Ru(bpy)₃²⁺ (?_ecl = 1) in acetonitrile (0.05 M tri-n-propylamine (TPrA) as an oxidative–reductive ECL coreactant). Also, qualitative studies using transmission filters suggest that the complexes emit ECL in approximately the same region as their photoluminescence, indicating that the same excited state is formed in both experiments.     

Electrogenerated chemiluminescence ethanol biosensor based on alcohol dehydrogenase functionalized Ru(bpy)3 doped silica nanoparticles

An ethanol biosensor, based on the electrogenerated chemiluminescence of Ru(bpy)₃²⁺-doped silica nanoparticles (RuSiNPs), was investigated in this study. The biosensor was a modified glassy carbon electrode, where alcohol dehydrogenase was crosslinked to RuSiNPs, and then immobilized on the electrode surface using chitosan. The results indicated that the biosensor exhibited excellent performance during ethanol determination with a wide linear range (10⁻⁷ to 10⁻² M), low detection limit (5.0 × 10⁻⁸ M) and good stability.     

Photoluminescence and electrogenerated chemiluminescence of a bis(bipyridyl)ruthenium(II)-porphyrin complex

The photoluminescence (PL) and electrogenerated chemiluminescence (ECL) of [H₂(MPy3,4DMPP)Ru(bpy)₂Cl](PF₆), where H₂MPy3,4DMPP = meso-tris-3,4-dimethoxyphenyl-mono-(4-pyridyl)porphyrin and bpy = 2,2′-bipyridine, are reported in acetonitrile. The compound has a complex absorbance spectrum with bands characteristic of both the porphyrin and ruthenium moieties. PL emission maxim are observed at 655 nm when excited at the maximum absorption intensity corresponding to the porphyrin Soret π → π^∗ band, and around 600 nm when excited at wavelengths corresponding to Ru(dπ)-bpy (π^∗) MLCT transition. The photoluminescence efficiency (?_em) of the 655 nm emission is 0.039 and that of the free porphyrin is 0.69 compared to at 0.042.[H₂(MPy3,4DMPP)Ru(bpy)₂Cl](PF₆) displays complex electrochemical behavior, with one electrochemically reversible Ru^II-Ru^III oxidation and two quasi-reversible waves at more cathodic potentials corresponding to the porphyrin moiety. Oxidative ECL was generated using the coreactant tri-n-propylamine (TPrA). ECL efficiencies (?_ecl) were 0.14 for [H₂(MPy3,4DMPP)Ru(bpy)₂Cl]⁺ and 0.099 for H₂MPy3,4DMPP using as the standard (?_ecl = 1). ECL intensity was linear with respect to concentration from 1 to 0.001 μM.The ECL intensity peaks at potentials corresponding to oxidation both the ruthenium and porphyrin moieties as well as TPrA, indicating that multiple pathways for formation of the excited state are possible. However, an ECL spectrum shows a band similar in energy and shape to that of the Soret emission (655 nm for the PL and 656 nm for the ECL, respectively), indicating the same excited state is formed in each experiment.     

Electrogenerated chemiluminescence reaction of lucigenin with isatin at a platinum electrode

The electrogenerated chemiluminescence (ECL) reaction of lucigenin with isatin was investigated at a platinum electrode in a neutral aqueous solution. The ECL intensity of lucigenin at ?0.65 V was greatly enhanced by isatin, and the ECL intensity was about 50 times higher than that of lucigenin without isatin. The enhanced ECL was believed to be produced by the chemiluminescence reaction between reduced lucigenin and superoxide anion that was generated by the reaction of electrochemically reduced isatin with dissolved oxygen. The conditions for the determination of isatin were optimized. Under the optimized condition, the enhanced ECL intensity vs. isatin concentration was linear in the range 4.8 × 10^?7?1.9 × 10^?5 g/mL; with a detection limit of 3.3 × 10^?8 g/mL, and the relative standard derivation 1.0 × 10^?6 g/mL isatin was 3.8%. Copyright © 2004 John Wiley & Sons, Ltd.     

Electrogenerated chemiluminescence from polymer-bound ortho-metallated iridium(III) systems.

Three ortho-metallated iridium complexes whose emission maxima fall in different regions of the electromagnetic spectrum were bound in either Nafion or poly(9-vinylcarbazole) and their electrogenerated chemiluminescence (ECL) reported. The reaction of F(Ir)pic [bis(3,5-difluoro-2-(2-pyridyl)phenyl-(2-carboxypyridyl)-iridium III] with the oxidative-reductive co-reactant tri-n-propylamine (TPrA) resulted in ECL when the iridium complex was bound in Nafion. No significant ECL was observed for (btp)(2)Ir(acac) (bis[2,(2'-benzothienyl)-pyridinato-N,C3'](acetylacetonate)Ir(III)), and Ir(ppy)(3) (where ppy = 2-phenylpyridine) under these conditions. However, all three compounds displayed ECL with TPrA when bound in poly(9-vinylcarbazole).     

Electrogenerated chemiluminescence of tris(2‐phenylpyridine)iridium(III) in water,acetonitrile and trifluorethanol

The spectroscopic, electrochemical and coreactant electrogenerated chemiluminescence (ECL) properties of Ir(ppy)3 (where ppy = 2‐phenylpyridine) have been obtained in aqueous buffered (KH2PO4), 50 : 50 (v/v) acetonitrile–aqueous buffered (MeCN–KH2PO4) and 30% trifluoroethanol (TFE) solutions. Tri‐n‐propylamine was used as the oxidative‐reductive ECL coreactant. The photoluminescence (PL) efficiency (ϕem) of Ir(ppy)3 in TFE (ϕem ≈ 0.029) was slightly higher than in 50 : 50 MeCN–KH2PO4 (ϕem ≈ 0.0021) and water (ϕem ≈ 0.00016) compared to a Ru(bpy)32+ standard solution in water (Φem ≈ 0.042). PL and ECL emission spectra were nearly identical in all three solvents, with dual emission maxima at 510 and 530 nm. The similarity between the ECL and PL spectra indicate that the same excited state is probably formed in both experiments. ECL efficiencies (ϕecl) in 30% TFE solution (ϕecl = 0.0098) were higher than aqueous solution (ϕecl = 0.00092) system yet lower than a 50% MeCN–KH2PO4 solution (ϕecl = 0.0091). Copyright © 2014 John Wiley & Sons, Ltd.     

Palladium(II) and platinum(II) complexes with polypyridylbenzene ligands

The ligands 1,3-bis(3-pyridyl)benzene (1), 1,3-bis(4-pyridyl)benzene (2) and 1,3,5-tris(4-pyridyl)benzene (3) have been prepared by Stille coupling of 3- or 4-trimethylstannylpyridine with the appropriate bromoarene. Ligands 1 and 2 react with [M(OTf)₂(dppp)] (M=Pd, Pt) to produce the dipalladium- or diplatinum-containing macrocycles [M₂(μ-1)₂(dppp)₂](OTf)₄ or [M₂(μ-2)₂(dppp)₂](OTf)₄. These have been characterized by NMR spectroscopy and mass spectrometry and, in the case of [Pd₂(μ-1)₂(dppp)₂](OTf)₄, by X-ray crystallography. The molecular structure of the [Pd₂(μ-1)₂(dppp)₂]⁴⁺ cation reveals a shallow arrangement of the aromatic rings, with the palladium atoms lying above and below. The tridentate ligand 3 reacts with [Pd(OTf)₂(dppp)] to produce a trimetallic species of the form [Pd₃(μ₃-3)₂(dppp)₃](OTf)₆.     

Structure and characterization of platinum(II) and platinum(IV) complexes with protonated nucleobase ligands

The reaction of H₂[PtCl₆] · 6H₂O and (H₃O)[PtCl₅(H₂O)] · 2(18C6) · 6H₂O (18C6 = 18-crown-6) with 9-methylguanine (MeGua) proceeded with the protonation of MeGua forming 9-methylguaninium hexachloroplatinate(IV) dihydrate (MeGuaH)₂[PtCl₆] · 2H₂O (1).The same compound was obtained from the reaction of Na₂[PtCl₆] with (MeGuaH)Cl.On the other hand, the reaction of guanosine (Guo) with (H₃O)[PtCl₅(H₂O)] · 2(18C6) · 6H₂O in methanol at 60 °C proceeded with the cleavage of the glycosidic linkage and with ligand substitution to give a guaninium complex of platinum(IV), [PtCl₅(GuaH)] · 1.5(18C6) · H₂O (2).Within several weeks in aqueous solution a slow reduction took place yielding the analogous guaninium platinum(II) complex, [PtCl₃(GuaH)] · (18C6) · 2Me₂CO (3).H₂[PtCl₆] · 6H₂O and guanosine was found to react in water, yielding (GuoH)₂[PtCl₆] (4) and in ethanol at 50 °C, yielding [PtCl₅(GuoH)] · 3H₂O (5).Dissolution of complexes 2 and 5 in DMSO resulted in the substitution of the guaninium and guanosinium ligands, respectively, by DMSO forming [PtCl₅(DMSO)]⁻.Reactions of 1-methylcytosine (MeCyt) and cytidine (Cyd) with H₂[PtCl₆] · 6H₂O and(H₃O)[PtCl₅(H₂O)] · 2(18C6) · 6H₂O resulted in the formation of hexachloroplatinates with N3 protonated pyrimidine bases as cation (MeCytH)₂[PtCl₆] · 2H₂O (6) and (CydH)₂[PtCl₆] (7), respectively. Identities of all complexes were confirmed by ¹H, ¹³C and ¹⁹⁵Pt NMR spectroscopic investigations, revealing coordination of GuoH⁺ in complex 5 through N7 whereas GuaH⁺ in complex 3 may be coordinated through N7 or through N9. Solid state structure of hexachloroplatinate 1 exhibited base pairing of the cations yielding (MeGuaH⁺)₂, whereas in complex 6 non-base-paired MeCytH⁺ cations were found. In both complexes, a network of hydrogen bonds including the water molecules was found. X-ray diffraction analysis of complex 3 exhibited a guaninium ligand that is coordinated through N9 to platinum and protonated at N1, N3 and N7. In the crystal, these NH groups form hydrogen bonds N–HO to oxygen atoms of crown ether molecules.     

Electrogenerated chemiluminescence of novel TiO2/CdS nanocomposites for sensitive assays of cancer cells

A novel TiO₂/CdS nanocomposite was prepared and used to fabricate an electrochemiluminescence (ECL) biosensor for the detection of cancer cells for the first time. The nanocomposite exhibited a strong cathodic ECL signal. Folic acid for targeting cell membranes was bound to a TiO₂/CdS/3-aminopropyltriethoxysilane film, and specific recognition of folic acid to targeting cells was achieved, leading to a significant decrease in ECL intensity. The decrease in ECL signal was logarithmically related to the cell concentration in the range of 150–9600 cells mL^-1. The ECL biosensor could provide a sensitive, selective, and convenient approach for early and accurate detection of cancer cells.     

Simple chemiluminescence determination of ketotifen using tris(1,10 phenanthroline)ruthenium(II)‐ Ce(IV) system

A new method using chemiluminescence (CL) detection has been developed for the simple determination of ketotifen fumarate (KF). The method is based on the catalytic effect of KF in the CL reaction of tris(1,10 phenanthroline)ruthenium(II), Ru(phen)₃²⁺, with Ce(IV) in sulfuric acid medium. The CL response was detected using a lab‐made chemiluminometer. Effects of chemical variables were investigated and under optimum conditions, the CL intensity was proportional to the concentration of the drug over the range 0.34‐34.00 µg mL^?1 KF. The limit of detection (S/N=3) was 0.09 µg mL^?1. Effects of common ingredients were investigated and the method was applied successfully for determining KF in pharmaceutical formulations and human plasma. The percent of relative standard deviation (n=11) at level of 3.4 µg mL^?1 of KF was 4.6% and the minimum sampling rate was 70 samples per hour. The possible CL mechanism is proposed based on the kinetic characteristic of the CL reaction, CL spectrum, UV‐Vis and phosphorescence spectra. Copyright © 2015 John Wiley & Sons, Ltd.     

The microwave synthesis of platinum(II) phosphine complexes

The microwave synthesis of a series of platinum(II) phosphine complexes is reported. The complexes dppePtCl₂ (dppe = bis(diphenylphosphino)ethane), dpppPtCl₂ (dppp = bis(diphenylphosphino)propane), dppmPtCl₂ (dppm = bis(diphenylphosphino)methane) and cis-(Ph₃P)₂PtCl₂ are synthesized from the reaction of potassium tetrachloroplatinate(II) and the phosphine. The isolated yields are 65% or better.     

Enhanced chemiluminescence of peroxomonosulfate–cobalt (II) system in the presence of dicarboxylic acids

In the present work, the effects of molecular mass aliphatic dicarboxylic acids on the HSO₅^‐–Co²⁺ chemiluminescence (CL) system were investigated. It was found that the aliphatic dicarboxylic acids could enhance the CL of the HSO₅^‐–Co²⁺ system. Moreover, the CL intensities improved regularly with increasing carbon chain length of the dicarboxylic acids. To investigate the CL enhancement mechanism, dynamic profiles, CL spectroscopy, ESR spectrum and the effects of various free radical scavengers on the CL system were employed. The results indicated that the enhancement of the CL should be attributed to the formation of peroxo‐diacid, which finally decomposed to the original dicarboxylic acid and singlet oxygen. The mechanism of the HSO₅^‐–Co²⁺‐dicarboxylic acid CL system was then proposed. Copyright © 2010 John Wiley & Sons, Ltd. Copyright © 2010 John Wiley & Sons, Ltd.     

Determination of pholcodine in syrups and human plasma using the chemiluminescence system of tris(1,10 phenanthroline)ruthenium(II) and acidic Ce(IV)

Pholcodine is an opiate derivative drug which is widely used in pediatric medicine. In this study, a chemiluminescence (CL) method is described that determines pholcodine in human plasma and syrup samples. This method is based on the fact that pholcodine can greatly enhance the weak CL emission of reaction between tris(1,10 phenanthroline)ruthenium(II), Ru(phen)₃²⁺, and acidic Ce(IV). The CL mechanism is described in detail using UV–vis light, fluorescence and CL spectra. Effects of chemical variables were investigated and under optimum conditions, CL intensity was proportional to the pholcodine concentration over the range 4.0 × 10^?8 to 8.0 × 10^?6 mol  L^?1. The limit of detection (LOD) (S/N = 3) was 2.5 × 10^?8 mol  L^?1. Percent of relative standard deviations (%RSD) for 3.0 × 10^?7 and 3.0 × 10^?6 mol  L^?1 of pholcodine was 2.9 and 4.0%, respectively. Effects of common ingredients were investigated and the method was applied successfully to the determination of pholcodine in syrup samples and human plasma.     

A new polymorph of dichlorido(1,10-phenanthroline)platinum(II)

A yet unreported polymorph of [PtCl₂(1,10-phenanthroline)] was obtained by slow decomposition, in CH₂Cl₂ solution, of [Pt{CH₂CH₂N(CH₂CH₃)₂-κC,κN}(1,10-phenanthroline)](ClO₄). The structure of the new orthorhombic form, III, (space group Pna2₁), is described and compared to those of the two already reported forms, I and II, which are monoclinic (space group P2₁/c) and orthorhombic (space group Pca2₁), respectively [21]. Polymorph III appears to be the least stable of the three.     

Heterobimetallic platinum(II)-palladium(II) complexes bridged by fluorobenzenethiolates. Structure and equilibria

Synthesis of the heterobimetallic platinum(II)-palladium(II) complexes with poly fluorinated benzenethiolates as intermetallic bridges, [(dppe)Pd(μ-SR_F)₂Pt(dppe)](SO₃CF₃)₂ with SR_F = p-SC₆F₄(CF₃) (1), SC₆F₅ (2), p-SC₆HF₄ (3) and o-SC₆H₄(CF₃) (4), have been accomplished either by a redistribution reaction in mixtures of the homonuclear bimetallic species, [(dppe)Pd(μ-SR_F)₂Pd(dppe)]²⁺/[(dppe)Pt(μ-SR_F)₂Pt(dppe)]²⁺ or by assembling the monometallic building blocks [(dppe)M(μ-SR_F)₂]/[(dppe)M′(solvent)₂]²⁺, M, M′ = Pd or Pt. Both experimental systems reach an equilibrium state which is independent of the temperature within the probed range, −90 °C to +50 °C. A single crystal of the heterobimetallic compound [(dppe)Pd(μ-SC₆F₅)₂Pt(dppe)](SO₃CF₃)₂(acetone)₂ (2) was isolated and analyzed by X-ray diffraction. Comparison with the corresponding structures exhibited by the homobimetallic analogous, [Pd₂(μ-SC₆F₅)₂(dppe)₂](SO₃CF₃)₂(acetone)₂ (5) and [Pt₂(μ-SC₆F₅)₂(dppe)₂](SO₃CF₃)₂(acetone)₂ (6) shows that all three structures are isostructural in space group . All three compounds exhibit a centrosymmetric planar [M₂(μ-S)₂] ring in which the sulfur substituents are arranged in an anti configuration.     

Water soluble platinum(II) and palladium(II) complexes of alkyl sulfonated phosphines

The reactions of the alkylsulfonated phosphines LM=Ph₂P(CH₂)_nSO₃Na/K (n=2, 3, 4) with K₂PtCl₄ and K₂PdCl₄ have been studied in homogeneous aqueous solution as a function of pH. In homogeneous acidic solution the protonated phosphines react to give cis- and trans-PtCl₂(LH)₂. The biphasic reaction between 1,5-cyclooctadiene platinum(II) chloride in dichloromethane and acidified aqueous LNa/K gives a higher proportion of the cis isomer. In neutral solution the initial reaction to give [PtCl(LNa/K)₃]⁺Cl⁻ is followed by slow formation of cis-PtCl₂(LNa/K)₂. K₂PdCl₄ reacts more rapidly to give PdCl₂(LNa/K)₂. In homogeneous alkaline solution rapid oxidation of the phosphine occurs with only small amounts of platinum complex being observable. The biphasic reaction yields phosphine oxide in the aqueous layer and a small amount of the chelate complexes PtL₂ in the organic. Representative complexes have been isolated and characterised and the mechanisms for the reactions discussed. The electrospray mass spectra of solutions of the isolated complexes have been recorded in both positive and negative ionisation modes. The positive ionisation spectra are complicated, but platinum and palladium containing ions derived from loss of chloride, H⁺ and HCl are observed in the negative ionisation spectra.     

Steric influence on platinum(II) ascorbate complexes

From the reaction between dihydroxoplatinum(II) and l-ascorbic acid, two types of platinum(II) ascorbate complexes were obtained and structurally characterized with ethylenediamine (en), N,N-dimethylethylenediamine (dmen) and N,N,N′-trimethylethylenediamine (trimen) as stabilizing ligands. In [Pt(en)(asc-C,O)] (1), [Pt(dmen)(asc-C,O)] (2) and [Pt(trimen)(asc-C,O)] (4), the ascorbate dianion forms a five-membered chelate ring, coordinating to the Pt(II) ion at the 2-carbon and the 5-oxygen atoms (C,O-chelate). From the same mother solution, crystals of [Pt(trimen)(asc-O,O′)] (3) were obtained during the precipitation of 4; in 3 the ascorbate is bound to the Pt at the 2- and 3-oxygen atoms (O,O′-chelate). Compounds 3 and 4 are the first well-characterized linkage isomers among the transition-metal ascorbate complexes. The O,O′-chelated 3 slowly changes to the C,O-chelated 4 in an aqueous solution. Bulkiness of the stabilizing ligand, i.e. en, dmen and trimen has an influence on the formation of the C,O-chelated species, 1, 2 and 4.