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1.
Electrocatalytic water oxidation to evolve O 2 was studied on a Nafion–RuO 2–Ru(bpy) 32+ composite electrode. The O 2 evolution current efficiency was largely improved for the multi-component electrode over the Nafion–RuO 2 and Nafion–Ru(bpy) 32+ individuals. The redox mediation through the Ru(bpy) 32+ was found to dominate over the RuO 2 catalytic effect in the water oxidation mechanism. The specific surface area of the RuO 2, 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. 相似文献
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. 相似文献
3.
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 ( Kf) have been evaluated by Benesi–Hildebrand method. The Kf 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. 相似文献
4.
Two mononuclear Ru II complexes of polypyridyl ligands, cis-[Ru(bpy) 2(4,4′-bpy)Cl](PF 6)·H 2O (1) and cis-[Ru(phen) 2(CH 3CN) 2](PF 6) 2 (2) (bpy=2,2′-bipyridyl, 4,4′-bpy=4,4′-bipyridyl, and PHEN=1,10-phenanthroline), have been synthesized and characterized by elemental analyses, IR and UV–vis spectra. The crystal structures of both complexes have been determined by X-ray diffraction, indicating that each Ru II center is hexa-coordinated (RuN 5Cl for 1 and RuN 6 for 2) and takes a distorted octahedral geometry. The favored feature of both complexes is that they are quite useful complex precursors for further constructing new functional architectures. 相似文献
5.
Excitation of solutions of Fe(bipy) 2(CN) 2 by a 266-nm laser pulse produces a hydrated electron and the oxidized complex, Fe(bipy) 2 (CN) 2+, in the primary photochemical step, in homogeneous aqueous solution as well as in aqueous solutions containing cetyltrimethylammonium bromide (CTAB) or sodium dodecyl sulfate (SDS) micelles. In all cases nascent hydrated electrons react with ground state Fe(bipy) 2(CN) 2 to form Fe(bipy) 2(CN) 2−, and comparison of the decay constants in the three media (H 2O: k = 2.8 × 10 10 M −1 s −1; CTAB: k = 2.9 × 10 10 M −1 s −1; SDS: k = 5.5 × 10 9 M −1 s −1), shows that the reaction is essentially unaffected by CTAB micelles but is much slower in SDS solution. Similar micellar effects were found for the back reaction between e aq− and Fe(bpy) 2(CN) 2+. Rate constants for the scavenging of the photogenerated hydrated electrons by methyl viologen (MV 2+) cations and NO 3− anions were measured in the three systems, and the results indicate that for scavenging by MV 2+ the rate constants are decreased in the micelle systems ( k in H 2O, 8.4 × 10 10; CTAB, 3.5 × 10 10 and SDS, 1.58 × 10 10 M −1 s −1), whereas for NO 3− the CTAB micelle decreases while the SDS micelle enhances the scavenging compared to water solution ( k in H 2O, 8.3 × 10 9; CTAB, 7 × 10 8; and SDS, 2.05 × 10 10 M −1 s −1). For the comproportionation reaction between Fe(bipy) 2(CN) 2+ and Fe(bipy) 2(CN) 2− both micelles reduce the rate ( k in H 2O, 3.3 × 10 10; CTAB, 2.3 × 10 10; and SDS, 1.05 × 10 10 M −1s −1), but while the reaction of Fe(bipy) 2(CN) 2+ with MV + is increased in CTAB compared to water, it is slowed in SDS ( k in H 2O, 2.4 × 10 10; CTAB, 8.9 × 10 10; and SDS, 1.8 × 10 10 M −1s −1). All effects observed in these microheterogeneous systems can be uniformly interpreted in terms of Coulombic interactions between the actual reactants and the charged surface of the micelles. 相似文献
6.
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. 相似文献
7.
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 H 2O 2 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 × 10 4. 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. 相似文献
8.
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 相似文献
9.
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. 相似文献
10.
The observed difference in transition strength for (SF 6) 2, (SiF 4) 2 and (SiH 4) 2 IR-predissociation spectra is explained by induction effects (μ 012/ R126) which have to be included in the interaction Hamiltonian in addition to the dominant dipole-dipole term (μ 012/ R123). 相似文献
11.
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(CH 2) 4Br](PF 6) 2. 相似文献
12.
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. 相似文献
13.
The generality of a two-electron reduction process involving an
mechanism has been established for M 3(CO) 12 and M 3(CO) 12− n(PPh 3) n (M = Ru, Os) clusters in all solvents. Detailed coulometric and spectral studies in CH 2Cl 2 provide strong evidence for the formation of an ‘opened’ M 3(CO) 122− species the triangulo radical anions M 3(CO) 12−· having a half-life of < 10 −6 s in CH 2Cl 2. However, the electrochemical response is sensitive to the presence of water and is concentration dependent. An electrochemical response for “opened” M 3(CO) 122− is only detected at low concentrations < 5 × 10 −4 mol dm −3 and under drybox conditions. The electroactive species ground at higher concentrations and in the presence of water M 3(CO) 112− and M 6(CO) 182− were confirmed by a study of the electrochemistry of these anions in CH 2Cl 2; HM 3(CO) 11− is not a product. The couple [M 6(CO) 18] −/2− is chemically reversible under certain conditions but oxidation of HM 3(CO) 11− is chemically irreversible. Different electrochemical behaviour for Ru 3(CO) 12 is found when [PPN][X] (X = OAc −, Cl −) salts are supporting electrolytes. In these solutions formation of the ultimate electroactive species [μ-C(O)XRu 3(CO) 10] − at the electrode is stopped under CO or at low temperatures but Ru 3(CO) 12−· is still trapped by reversible attack by X presumably as [η 1-C(O)XRu 3(CO) 11] −. It is shown that electrode-initiated electron catalysed substitution of M 3(CO) 12 only takes place on the electrochemical timescale when M = Ru, but it is slow, inefficient and non-selective, whereas BPK-initiated nucleophilic substitution of Ru 3(CO) 12 is only specific and fast in ether solvents particulary THF. Metal---metal bond cleavage is the most important influence on the rate and specificity of catalytic substitution by electron or [PPN]-initiation. The redox chemistry of M 3(CO) 12 clusters (M = Fe, Ru, Os) is a consequence of the relative rates of metal---metal bond dissociation, metal-metal bond strength and ligand dissociation and in many aspects resembles their photochemistry. 相似文献
14.
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 ·. 相似文献
15.
Ru(II)-complex functionalized silica nanoparticles(nano-SiO 2) were prepared via a coordination reaction of cis-dichlorobis(2,2'-bipyridine)ruthenium[Ru(bpy) 2Cl 2] complex with poly(4-vinylpyridine)(P4VP)-modified nano-SiO 2 particles. Both the Ru-complex and the functionalized nano-SiO 2P4VP-Ru(bpy) hybrids were doped in poly(methyl methacrylate)(PMMA) to form optically transparent thin films. The composition and spectroscopic properties of the nano-SiO 2P4VP-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) 2Cl 2. The as-prepared nano-SiO 2P4VP-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) 22+/3+ immobilized on the nano-SiO 2 particles. 相似文献
16.
Polymerizations of ethylene have been carried out by using Cp 2*Zr(NMe 2) 2 (Cp *=C 5Me 5) compound combined with common alkyl aluminums (AlR 3) and methylaluminoxane (MAO) as cocatalysts. The AlMe 3 cocatalyzed system showed no activity due to the formation of stable but inactive heterodinuclear [Cp 2*2Zr(μ-Me) 2AlMe 2] + cations; however, the bulkier AlR 3 [AlEt 3, Al( i-Bu) 3 and Al( i-Bu) 2H] cocatalyzed systems showed very high activities. Especially, Cp 2*Zr(NMe 2) 2/Al( i-Bu) 3 catalyst showed higher catalytic activity and produced higher molecular weight (MW) polymer than Cp 2*Zr(NMe 2) 2/MAO catalyst, demonstrating both MAO and bulky AlR 3 are effective cocatalysts for Cp 2*Zr(NMe 2) 2 compound. 相似文献
17.
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. 相似文献
18.
<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. 相似文献
19.
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 H 2O, propylene carbonate, CH 3CN and 4:1 (v/v) C 2H 5OH---CH 3OH; 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 Δ E, 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. 相似文献
20.
The thermally (decomp. temp. 300°C) and completely air stable, novel coordination polymers [(Me 3Sn IV) 2(Me 3Sb V)M II(CN) 6] ∞ with M = Fe and Ru can be prepared by co-precipitation from aqueous solutions of Me 3SnCl, Me 3SbBr 2 and K 4[(M(CN) 6], or, alternatively, by the ion-exchange-like reaction of the polymers [A(Me 3Sn) 3M(CN) 6] ∞ (A + = Et 4N +, Cp 2Co +, Me 3Sn + etc.) with Me 3SbBr 2. IR-spectroscopic findings suggest a statistical distribution of quasi-octahedral M(CN-Sn··) 6-x(CNSb ··) x building blocks (with x = 0–6) within a three-dimensional network. 相似文献
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