Persulphate quenching of the excited state of ruthenium(II) tris-bipyridyl dication: thermal reactions

The rate constant for the reaction between the sulphate radical (SO₄^√−) and the ruthenium (II) tris-bipyridyl dication (Ru(bipy)₃²⁺) is (3.3±0.2)×10⁹ mol⁻¹ dm³ s⁻¹ in 1 mol dm⁻³ H₂SO₄ and (4.9±0.5)×10⁹ mol⁻¹ dm³ s⁻¹ in 0.1 mol dm⁻³, pH 4.7 acetate buffer. The SO₄^√−radical produced by the electron transfer quenching of Ru(bipy)₃^2+* by S₂O₈²⁻ reacts rapidly with both acetate buffer and chloride ions. These side reactions result in a reduction in the overall quantum yield of Ru(bipy)₃³⁺ production and reduced reaction selectivity when Ru(bipy)₃^2+* is quenched by persulphate.     

Photophysics of ruthenium(II) complexes with 2-(2′-pyridyl) pyrimidine and 2,2′-bipyridine ligands in fluid solution

The photophysics of three complexes of the form Ru(bpy)₃₋(pypm)²⁺ (where bpy2,2′-bipyridine, pypm 2-(2′-pyridyl)pyrimidine and P=1, 2 or 3) was examined in H₂O, propylene carbonate, CH₃CN and 4:1 (v/v) C₂H₅OH---CH₃OH; comparison was made with the well-known photophysical behavior of Ru(bpy)₃²⁺. The lifetimes of the luminescent metal-to-ligand charge transfer (MLCT) excited states were determined as a function of temperature (between −103 and 90 °C, depending on the solvent), from which were extracted the rate constants for radiative and non-radiative decay and ΔE, the energy gap between the MLCT and metal-centered (MC) excited states. The results indicate that ^*Ru(bpy)₂(pypm)²⁺ decays via a higher lying MLCT state, whereas ^*Ru(pypm)₃²⁺ and ^*Ru(pypm)₂(bpy)²⁺ decay predominantly via the MC state.     

Synthesis and Fluorescence of a New Active Material for Electrochemiluminescent Sensor:Ru(phen)2[phen-NHCO(CH2)4Br](PF6)2

Recently, much attention has been paid to Ru(II) complexes because of their excellent properties of photochemistry, phtophysis. Bis(2,2'-bipyridine)[4-methyl-4'-(6-bromohexyl)-2,2'-bipyridine] ruthenium(II) perchlorate has been used as an active material for electrochemiluminescent (ECL) sensor for selective detection of oxalic acid.It is known that ECL efficiency of Ru(phen)₃²⁺ is much higher than that of Ru(bpy)₃²⁺. In order to make out more efficient ECL sensor, we have designed and synthesized a new Ru(II) complex, Ru(phen)₂[phen-NHCO(CH₂)₄Br](PF₆)₂.     

Characterization of the low-oxidation-potential electrogenerated chemiluminescence of tris(2,2′-bipyridine)ruthenium(II) with tri-n-propylamine as coreactant

The electrogenerated chemiluminescence (ECL) of the Ru(bpy)₃²⁺ (bpy, 2,2′-bipyridine)/tri-n-propylamine (TPrA) system can be produced at an oxidation-potential well before the oxidation of Ru(bpy)₃²⁺. Here, we describe the unique features of the low-oxidation-potential (LOP) ECL. The LOP ECL exhibited strong dependence on solution pH with the maximum emission at pH  7.7. Compared with the conventional ECL, the LOP ECL was much more significantly diminished at high pH (>10), probably due to the short lifetime of TPrA cation radical which is a crucial intermediate for the LOP emission. It was also found that the preceding deprotonation step played an important role in TPrA oxidation at neutral pH and would remarkably influence the emission intensity. As excess intermediate radicals were produced upon rapid TPrA oxidation, only 5 mM TPrA was needed to achieve the maximum LOP ECL intensity in detecting trace Ru(bpy)₃²⁺ (<1 μM) and the LOP ECL response to Ru(bpy)₃²⁺ concentration was linear. Compared with the conventional Ru(bpy)₃²⁺/TPrA ECL, the LOP ECL technique not only produces higher emission intensity at lower oxidation-potential, but also significantly reduces the amount of the coreactant.     

Rates of virtually self-exchange energy transfer processes of ruthenium(II) polypyridine complexes

The rate constants of electronic energy transfer from the lowest excited state of Ru(bpy)₂(L)²⁺ or Ru(bpy)(L)₂²⁺ 10 Ru(L)₃²⁺ (b     

Development of a triple channel detection probe for hydrogen peroxide

The rapid and reliable measurement of hydrogen peroxide (H₂O₂) is imperative for many areas of technology, including pharmaceutical, clinical, food industry and environmental applications. In this work, a novel multifunctional complex, [Ru(bpy)₂(luminol-bpy)](PF₆)₂ (bpy: 2,20'-bipyridine), was designed and synthesized by incorporating a Ru(II) complex with a luminal group. In the presence of horseradish peroxidase (HRP), reaction of [Ru(bpy)₂(luminol-bpy)]²⁺ with H₂O₂ can be monitored by three sensing channels including photoluminescence (PL), chemiluminiscence (CL) and eletrochemiluminiscence (ECL). The quantitative assays for H₂O₂ in aqueous solutions using [Ru(bpy)₂(Luminalbpy)]( PF₆)₂ as a probe were established with PL, ECL and CL signal output modes, respectively.     

Nafion–RuO2–Ru(bpy)3 composite electrodes for efficient electrocatalytic water oxidation

Electrocatalytic water oxidation to evolve O₂ was studied on a Nafion–RuO₂–Ru(bpy)₃²⁺ composite electrode. The O₂ evolution current efficiency was largely improved for the multi-component electrode over the Nafion–RuO₂ and Nafion–Ru(bpy)₃²⁺ individuals. The redox mediation through the Ru(bpy)₃²⁺ was found to dominate over the RuO₂ catalytic effect in the water oxidation mechanism. The specific surface area of the RuO₂, which was prepared at different temperatures (300–700°C), used in fabricating the composite electrode also played an important role in the overall water oxidation mechanism. Both the reaction and electrode parameters were optimized to get effective electrocatalytic current values in this study.     

Effect of Ionic Strength on the Electrochemiluminescence Generation by Tris(2,2'-bipyridyl)ruthenium(II)/Tri-n-propylamine

Electrochemiluminescence(ECL) is a powerful transduction technique used in biosensing and in vitro diagnosis, while the mechanism of ECL generation is complicated and affected by various factors. Herein the effect of ionic strength on ECL generation by the classical tris(2,2'-bipyridyl)ruthenium(II)[Ru(bpy)₃²⁺]/tri-n-propylamine(TPrA) system was investigated. It is clear that the ECL intensity decreases significantly with the increase of ionic strength, most likely arising from the reduced deprotonation rate of TPrA^+·. We further combined microtube electrode(MTE) with ECL microscopy to unravel the evolution of ECL layer with the variation of ionic strength. At a low concentration of Ru(bpy)₃²⁺, the thickness of ECL layer(TEL) nearly kept unchanged with the ionic strength, indicating the surface-confined ECL generation is dominated by the oxidative-reduction route. While at a high concentration of Ru(bpy)₃²⁺, ECL generation is dominated by the catalytic route and TEL increases remarkably with the increase of ionic strength, because of the extended diffusion length of Ru(bpy)₃³⁺ at a reduced concentration of TPrA^·.     

SOLID PHASE PHOTOREDUCTION OF METHYLVIOLOGEN ON CELLULOSE SENSITIZED BY TRIS(2,2'-BIPYRIDYL)RUTHENIUM COMPLEX

–Methylviologen (MV²⁺) adsorbed on cellulose could be reduced photochemically in the solid phase sensitized by tris(2,2'-bipyridyl)ruthenium(II) complex, [Ru(II)(bpy)₃], using disodium ethylene-diaminetetraacetic acid (Na₂EDTA) as a reducing agent. Formation of the cation radical (MV ⁺.) was confirmed by visible and EPR spectra. The MV⁺. formed on cellulose was remarkably stable against air oxidation and rapidly accumulated even by the irradiation under air. Water adsorbed on the cellulose greatly retarded the photoreaction. Action spectrum showed that the excitation of Ru(II)(byp)₃ is responsible for the photochemical reaction. The quenching of the emission from Ru(II)(bpy)*₃ by MV²⁺. indicated that a primary photochemical reaction occurs between Ru(II)(bpy)*₃ and MV²⁺. The main reaction path is the reduction of MV²⁺ by Ru(II)(bpy)₃, giving MV⁺. and Ru(III)(bpy)₃, followed by the reduction of Ru(III)(bpy)₃ to Ru(II)(bpy)₃ with Na₂EDTA, which in turn is oxidized to give carbon dioxide.     

Stabilization and electron spin resonance characterization of Ru(bpy)3 and Ru(bpy)3 by radiolysis of Ru(bpy)3 adsorbed on silica gel

Ru(bpy)₃³⁺, which is important in artificial photosynthetic systems due to its high reduction potential, is stabilized together with its counter anion, Ru(bpy)₃⁺, by radiolysis of Ru(bpy)₃²⁺ adsorbed on silica gel at 77 K. Both species are characterized by electron spin resonance.     

毛细管电泳电致化学发光检测血浆中布比卡因

布比卡因是一种外科局部麻醉剂,使用过量会导致中枢神经系统和心脏血管系统中毒^[1],可引起心脏停博.高效液相色谱和毛细管电泳(CE)^[2]是该药常用的检测方法.     

Proton solvates, H·nH2O·mL, formed by diphosphine dioxides with chlorinated cobalt(III) dicarbollide acid

Interaction of hydrated proton, H₅O₂⁺·(H₂O)₄, in dichloroethane solutions with diphosphine dioxides (L) having methyl (Ph₄Me), ethyl (Ph₄Et) and polyoxyethylene chains (Ph₄PEG) linking two diphenyl phosphine oxide groups has been investigated. A bulky counter ion: chlorinated cobalt(III) bis(dicarbollide), [Co(C₂B₉H₈Cl₃)₂]⁻, minimizes perturbation of the cation. At low concentrations, Ph₄Et and Ph₄PEG form anhydrous 1:1 complexes with (P)O–H⁺–O(P) fragment having very strong symmetrical H-bonds. At these conditions Ph₄Me form another compound, H₅O₂⁺·L(H₂O)₂, due to lower PO basicity and optimal geometry of the chelate cycle. At higher concentrations, Ph₄Me and Ph₄Et form isostructural complexes H₅O₂⁺·L₂, whereas Ph₄PEG forms only a 1:1 complex with proton dihydrate, H₃O⁺·H₂O. In excess of free Ph₄Me and Ph₄Et a water molecule is introduced to the first coordination sphere of H₅O₂⁺ and the average molar ratio L/H₅O₂⁺ of the complexes exceeds 2. The composition of these complexes as a function of L and its concentration is discussed.     

Enhancement of the chemiluminescence of penicillamine and ephedrine after derivatization with aldehydes using tris(bipyridyl)ruthenium(II) peroxydisulfate system and its analytical application

A novel sequential injection (SI) method was developed for the determination of penicillamine (PA) and ephedrine (EP) based on the reaction of these drugs with tris(bipyridyl)ruthenium(II) (Ru(bpy)₃²⁺) and peroxydisulfate (S₂O₈²⁻) in the presence of light. Derivatization of PA and EP with aldehydes has resulted in a significant enhancement of the chemiluminescence emission signal by at least 25 times for PA and 12 times for EP, leading to better sensitivities and lower detection limits for both drugs. The instrumental setup utilized a syringe pump and a multiposition valve to aspirate the reagents, (Ru(bpy)₃²⁺ and S₂O₈²⁻), and a peristaltic pump to propel the sample. The experimental conditions affecting the derivatization reaction and the chemiluminescence reaction were systematically optimized using the univariate approach. Under the optimum conditions linear calibration curves between 0.2–24 μg mL⁻¹ for PA and 0.2–20 μg mL⁻¹ for EP were obtained. The detection limits were 0.1 μg mL⁻¹ for PA and 0.03 μg mL⁻¹ for EP. The procedure was applied to the analysis of PA and EP in pharmaceutical products and was found to be free from interferences from concomitants usually present in these preparations.     

Multi-functional Photoelectric Sensor Based on a Three-fold Interpenetrated Cd(II) Coordination Polymer for Sensitively Detecting Different Ions

Athree-fold interpenetrated cadmium coordination polymer[Cd₃(BTC)₂(H₂O)₉]·2H₂O(CP 1)(H₃BTC=1,3,5-benzenetricar-boxylic acid) was selected and synthesized to investigate its photoelectric properties. CP 1 showed excellent sensitivity for Cr₂O₇^2- and Fe³⁺, low limit of detection(LOD:0.39 µmol/L for Cr₂O₇^2- and 1.72 µmol/L for Fe³⁺) and stability as electrochemical sensor. More importantly, fluorescence sensing studies indicated that CP 1 exhibits sensing activity for Fe³⁺, Fe²⁺, and MnO₄^- with good cyclic stability and selectivity. Low LOD and high-sensitivity capability of CP 1 make it a potential multifunctional photoelectric sensor.     

8-羟基喹啉合十钒酸盐的研究(Ⅲ)——锂、钾、铵盐的合成、鉴定与性质

在合成与研究钠盐的基础上^[1,2],我们又合成了锂、钾和铵盐,通过元素分析、分子量测定、质谱分析、X射线衍射、紫外和红外吸收光谱分析和热重分析确定了新化合物的组成与化学式并推测了化合物的结构式。     

Preparation,Characterization, Luminescent and Electrochemical Properties of Ru(bpy)2-functionalized Silica Nanoparticles

Ru(II)-complex functionalized silica nanoparticles(nano-SiO₂) were prepared via a coordination reaction of cis-dichlorobis(2,2'-bipyridine)ruthenium[Ru(bpy)₂Cl₂] complex with poly(4-vinylpyridine)(P4VP)-modified nano-SiO₂ particles. Both the Ru-complex and the functionalized nano-SiO₂P4VP-Ru(bpy) hybrids were doped in poly(methyl methacrylate)(PMMA) to form optically transparent thin films. The composition and spectroscopic properties of the nano-SiO₂P4VP-Ru(bpy) hybrids were evaluated with the help of thermogravimetric and elemental analysis, and UV-Vis absorption spectroscopy, infrared spectroscopy, X-ray photoelectron spectroscopy, and fluorescence spectroscopy. Microscopy images revealed that the nanohybrids were approximately 12 nm in diameter and readily formed aggregates following the functionalization with P4VP and Ru(bpy)₂Cl₂. The as-prepared nano-SiO₂P4VP-Ru(bpy) hybrids produced emissions at approximately 604 and 654 nm under radiation both in solution and in doped thin films. Finally, cyclic voltammetry studies on the nanohybrid-modified electrode revealed a redox couple with the cathodic and anodic potentials at approximately 0.28 and 0.73 V(vs. Ag/AgCl), attributed to the one electron transfer of Ru(bpy)₂^2+/3+ immobilized on the nano-SiO₂ particles.     

Electrochemiluminescence sensor using tris(2,2′-bipyridyl)ruthenium(II) immobilized in Eastman-AQ55D–silica composite thin-films

An electrochemiluminescence (ECL) sensor with good long-term stability and fast response time has been developed. The sensor was based on the immobilization of tris(2,2′-bipyridyl)ruthenium(II) (Ru(bpy)₃²⁺) into the Eastman-AQ55D–silica composite thin films on a glassy carbon electrode. The ECL and electrochemistry of Ru(bpy)₃²⁺ immobilized in the composite thin films have been investigated, and the modified electrode was used for the ECL detection of oxalate, tripropylamine (TPA) and chlorpromazine (CPZ) in a flow injection analysis system and showed high sensitivity. Because of the strong electrostatic interaction and low hydrophobicity of Eastman-AQ55D, the sensor showed no loss of response over 2 months of dry storage. In use, the electrode showed only a 5% decrease in response over 100 potential cycles. The detection limit was 1 μmol l⁻¹ for oxalate and 0.1 μmol l⁻¹ for both TPA and CPZ (S/N=3), respectively. The linear range extended from 50 μmol l⁻¹ to 5 mmol l⁻¹ for oxalate, from 20 μmol l⁻¹ to 1 mmol l⁻¹ for TPA, and from 1 μmol l⁻¹ to 200 μmol l⁻¹ for CPZ.     

The electrolyte NRTL model and speciation approach as applied to multicomponent aqueous solutions of H2SO4, Fe2(SO4)3, MgSO4 and Al2(SO4)3 at 230–270 °C

This work presents chemical modeling of solubilities of metal sulfates in aqueous solutions of sulfuric acid at high temperatures. Calculations were compared with experimental solubility measurements of hematite (Fe₂O₃) in aqueous ternary and quaternary systems of H₂SO₄, MgSO₄ and Al₂(SO₄)₃ at high temperatures. A hybrid model of ion-association and electrolyte non-random two liquid (ENRTL) theory was employed to fit solubility data in three ternary systems H₂SO₄–MgSO₄–H₂O, H₂SO₄–Al₂(SO₄)₃–H₂O at 235–270 °C and H₂SO₄–Fe₂(SO₄)₃–H₂O at 150–270 °C. Employing the Aspen Plus™ property program, the electrolyte NRTL local composition model was used for calculating activity coefficients of the ions Al³⁺, Mg²⁺ Fe³⁺ and SO₄²⁻, HSO₄⁻, OH⁻, H₃O⁺, respectively, as well as molecular species. The solid phases were hydronium alunite (H₃O)Al₃(SO₄)₂(OH)₆, hematite Fe₂O₃ and magnesium sulfate monohydrate (MgSO₄)·H₂O which were employed as constraint precipitation solids in calculating the metal sulfate solubilities. A correlation for the equilibrium constants of the association reactions of complex species versus temperature was implemented. Based on the maximum-likelihood principle, the binary interaction energy parameters for the ionic species as well as the coefficients for equilibrium constants of the reactions were obtained simultaneously using the solubility data of the ternary systems. Following that, the solubilities of metal sulfates in the quaternary systems H₂SO₄–Fe₂(SO₄)₃–MgSO₄–H₂O, H₂SO₄–Fe₂(SO₄)₃–Al₂(SO₄)₃–H₂O at 250 °C and H₂SO₄–Al₂(SO₄)₃–MgSO₄–H₂O at 230–270 °C were predicted. The calculated results were in excellent agreement with the experimental data.     

Charge transfer photochemistry of Ru(bpz)3 with carboxylic acids and carboxylate ions

Ru(bpz)₃²⁺ (bpz = 2,2′-bipyrazine) has six peripheral uncoordinated nitrogen atoms potentially available for protonation in presence of acids. The emission from ^*Ru(bpz)₃²⁺ is efficiently quenched by organic acids and the observed quenching rate constants are explained in terms of proton transfer from acids to ^*Ru(bpz)₃²⁺. The absorption and emission intensity of Ru(bpz)₃²⁺ increases with increasing concentration of carboxylate ion suggesting the complex formation between the two reactants in the ground state. From these studies, the formation constant (K_f) have been evaluated by Benesi–Hildebrand method. The K_f values indicate that generally the ion pair association constants estimated from absorption and emission techniques are comparable and these values are sensitive to the structure of the carboxylate ions.     

SO_4~(2-)功能化处理对Fe_2O_3催化剂上氨选择性催化还原NO_x性能的促进机理研究

采用沉淀法制备了Fe(OH)_3和Fe_2O_3。通过硫酸化处理得到SO_4~(2-)/Fe(OH)_3和SO_4~(2-)/Fe_2O_3两种催化剂,并将其应用于氨选择性催化还原NO_x(NH_3-SCR)反应,研究了SO_4~(2-)功能化处理对Fe_2O_3催化剂上NH_3-SCR脱硝性能的促进机理。结果表明,与纯的Fe_2O_3相比,硫酸化处理得到的催化剂上SCR活性得到显著提升;其中,SO_4~(2-)/Fe(OH)_3表现出更加优异的催化性能,在250-450℃时NO_x转化率高于80%,且具有优异的稳定性和抗H_2O+SO_2性能。XRD、Raman、TG、FT-IR、H_2-TPR、NH_3-TPD和in situ DRIFTS等表征结果显示,硫酸功能化处理能抑制Fe_2O_3的晶粒生长,同时SO_4~(2-)与Fe~(3+)结合形成硫酸盐复合物,提高了催化剂表面酸性位点的数量和酸强度,抑制了Fe_2O_3上的氨氧化反应,从而提高了其脱硝催化性能。