Determination of Amino Acids by Ru(bpy)_3~(2+) Cathodic Electrochemiluminescence with High Sensitivity

The unique cathodic electrochemiluminescence(ECL) emission of Ru(bpy)32+(bpy=2,2′-bipyridine) was observed via Nafion film at Au electrode[Au/Nafion/Ru(bpy)32+] at about 0.20 V(vs. Ag/AgCl) and applied to the determination of several amino acids without prior derivatization with high sensitivity. The cathodic electrochemilumi-nescence(ECL) exhibits the detection limits and linear ranges of several amino acids comparable to or better than those of capillary electrophoresis with conventional ECL detection method(at 1.10—1.20 V vs. Ag/AgCl) based on precolumn derivatization. The results suggest that the cathodic ECL is promising for the detection of amino acids in bioanalysis.     

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.     

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     

Hydrogen peroxide photoproduction by the semicarbazide—tris(2,2′-bipyridine)ruthenium(II)—oxygen system

A light-driven system consisting of tris(2,2′-bipyridine)ruthenium(II) (Ru(bpy)₃²⁺) as the photosensitizer, semicarbazide as the electron donor and molecular oxygen as the electron acceptor has been employed for hydrogen peroxide production. The efficiency of this photosystem markedly depends on pH: while the peroxide yield is almost negligible at acid, neutral or slightly alkaline pH, it reaches significant values at high hydroxide concentrations, the initial rate of H₂O₂ formation drastically increasing from pH 12 to pH 14. In 1 M NaOH solutions containing Ru(bpy)₃²⁺ and semicarbazide at optimum concentrations, the number of catalytic cycles (or turnover number) undergone by the ruthenium complex over the complete course of the photochemical reaction is as high as 1.1 × 10⁴.

Spectrofluorometric and laser flash photolysis techniques were used to study the primary photochemical reactions involving the excited state of the ruthenium complex as well as the photochemically generated species Ru(bpy)₃³⁺ and Ru(bpy)₃⁺. It is proposed that at pH 14 a sequence of reactions leading to O₂ photoreduction by electrons from semicarbazide takes place, with the concomitant formation of H₂O₂; the excited state of Ru(bpy)₃²⁺ appears to react via oxidative quenching by oxygen rather than via reductive quenching by semicarbazide. At neutral pH, in contrast, there is no H₂O₂ formation owing to the fact that semicarbazide is unable to reduce (Ru(bpy)₃³⁺ to Ru(bpy)₃²⁺, although the photoexcited ruthenium complex is quenched equally by oxygen.     

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.     

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^·.     

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.     

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.     

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.     

Effect of Electron-Donating/Withdrawing for Hydroxyl Carboxylic Acid on the Tris(2,2,-bipyridyl) Ruthenium(Ⅲ) Chemiluminescence

Since 1966 Hercules and Lytle first reported visible light was generated upon a reduction of tris(2,2'-bipyridyl) ruthenium(Ⅲ), Ru(bpy)₃³⁺, with either hydrazine or hydroxide ion.     

Electrochemiluminescent behavior of melatonin and its important derivatives in the presence of Ru(bpy)(3)(2+)

Melatonin and some of its important derivatives were found to be able to enhance the ECL of Ru(bpy)₃²⁺ in an alkaline Britton–Robinson buffer solution. The optimum conditions for the enhanced ECL, such as the selection of applied potential mode, type of buffer solution, pH effect and effect of Ru(bpy)₃²⁺ concentration have been investigated in detail in this paper. Under the optimum conditions, the enhanced ECL is linear with the concentration of melatonin and its derivatives over the wide range, and the detection limit for these compounds was found to be in the range of 5.0 × 10⁻⁸ to 1.0 × 10⁻¹⁰ mol L⁻¹. The proposed procedure was applied for the determination of drug in tablets with recoveries of 85–93%. A possible mechanism for the enhanced ECL of Ru(bpy)₃²⁺ by melatonin and its derivatives was proposed, and the relationship between molecular structure of melatonin and its derivatives and the enhanced ECL behavior was also discussed.     

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.     

Capillary electrophoresis with electrochemiluminescence detection of procyclidine in human urine pretreated by ion-exchange cartridge

This paper describe a Ru(bpy)₃²⁺ based electrochemiluminescence (ECL) method to detect procyclidine in human urine following separation by capillary electrophoresis (CE). An ECL detection cell was designed for post-column addition of Ru(bpy)₃²⁺. Parameters affecting separation and detection were optimized, leading to a detection limit of 1×10⁻⁹ mol/l in an on-capillary stacking mode. For application in urine, a cartridge packed with slightly acidic cation-exchange resin was used to eliminate the matrix effects of urine and improve the detection sensitivity. Extraction recovery was nearly 90%.     

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.     

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.     

Ru(bpy)2(NCS)2染料敏化CdS/Zn2+TiO2复合半导体纳米多孔膜的光电化学

采用水热法合成了Zn²⁺离子掺杂的TiO₂纳米粒子[Zn²⁺掺杂量0.5%(物质的量的比)],并用光电化学方法研究了经Ru(bpy)₂(NCS)₂(bpy=2,2′bipyridine₄,4′dicarboxylicacid)分别敏化的掺杂Zn²⁺的TiO₂电极(简写为Zn²⁺-TiO₂)和CdS/Zn²⁺-TiO₂复合半导体纳米多孔膜电极的光电化学行为.实验证明Ru(bpy)₂(NCS)₂敏化CdS/Zn²⁺-TiO₂复合半导体纳米多孔膜电极比单独敏化Zn²⁺-TiO₂电极的光电转换效率高,且敏化Zn²⁺TiO₂电极和敏化CdS/Zn²⁺TiO₂复合半导体纳米多孔膜电极比Zn²⁺-TiO₂电极的光电流产生的起始波长都向长波方向移动.在360600nm范围内,Ru(bpy)₂(NCS)₂敏化CdS/Zn²⁺-TiO₂复合半导体纳米多孔膜电极光电转换效率最好.     

阳离子交换型聚合物AQ薄膜修饰碳纤维电极及伏安行为

本文成功地制备了Eastman-AQ-55D聚合物修饰碳纤维电极,用循环伏安法探讨了一些实验参数的影响,并对Ru(NH₃)₆³⁺、甲基紫精进行了分析,结果表明,AQ-55D修饰的微电极稳定性好,修饰方法简单,灵敏度和选择性都有一定的提高,Ru(NH₃)₆³⁺、甲基紫精的峰电流与浓度在1.2×10^-6～1.2×10^-5mol/L、1.7×10^-6～1.4×10^-5mol/L范围内呈线性关系,其相关系数分别为0.999、0.998.利用此电极测定了几种离子在膜中的扩散系数.     

Fabrication and Photoelectrochemical Properties of [Ru(bpy)2dppz]2+ on ITO Electrode Associated with the Oxidation of Guanine

<正>Electrochemical assembly of[Ru(bpy)_2dppz]~(2+){bpy=2,2'-bipyridine,dppz=dipyrido[3,2-a:2',3'-c]phenazine} on an ITO electrode in the presence of guanine and photoelectrochemical properties of the assembled layer were investigated.It has been found that[Ru(bpy)_2dppz]~(3+/2+) can be assembled onto the ITO electrode by the method of repetitive voltammetric sweeping,and the assembly is enhanced by guanine.The peak currents of prewaves increase linearly up to a guanine concentration of 0.25 mmol/L.More importantly,upon illumination with 470 nm light source and at an applied potential of 0.2 V,cathodic current for the fabricated layer on the ITO electrode indicate a linear enhancement with the rise of guanine concentration.Meanwhile,[Ru(bpy)_2dppz]~(2+) can be served as an excellent mediator to prompt the oxidation of guanine,and the mediated peak current increases linearly with added guanine concentration from 0.01 to 0.25 mmol/L.In addition,the assembly mechanism of[Ru(bpy)_2dppz]~(2+) on the ITO electrode associated with the oxidation of guanine and the assistance of light irradiation were discussed.     

Electrochemiluminescent behavior of allopurinol in the presence of Ru(bpy)(3)(2+)

The electrochemiluminescent (ECL) response of allopurinol was studied in aqueous media over a wide pH range (pH 2–13) using flow injection (FI) analysis. It was revealed that allopurinol itself had no ECL activity, but could greatly enhance the ECL of Ru(bpy)₃²⁺ in alkaline media giving rise to a sensitive FI-ECL response. The effects of experimental conditions including the mode of applied voltage signal, the potential of working electrode, pH value, the flow rate of carrier solution, and the concentration of Ru(bpy)₃²⁺ and allopurinol on the ECL intensity were investigated in detail. The most sensitive FI-ECL response of allopurinol was found at pH 12.0, where the FIA-ECL intensity showed a linear relationship with concentration of allopurinol in the range 1 × 10⁻⁸ mol L⁻¹ to 5 × 10⁻⁷ mol L⁻¹, and the detection limit was 5 × 10⁻⁹ mol L⁻¹.     

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.