Ru Bipy Research Articles

Electrochemical properties of outer-sphere associates of bipyridyl and sepulchrate metal complexes with (thia)calix[4]arenes

The electrochemical one-electron reduction (oxidation) of bipyridyl metal complexes ([Co(bipy)3]3+, [Cr(bipy)3]3+, [Fe(bipy)3]2+, [Ru(bipy)3]2+ (as well as Co(III) sepulcrate)) with water-soluble (thia)calix[4]arenes has been studied by means of cyclic voltammetry. It has been shown that [M(bipy)3]3+/2+ bind to (thia)calix[4]arenes via sulfonate groups of the upper rim. Oxidized forms bind stronger than reduced ones leading to reduction (oxidation) of half-wave cathodic shift. The effect of predominant stabilization of oxidized forms of metal complexes for carboxylated calix[4]arene is stronger than for thiacalix[4]arene (ΔΔG0 = − 7.8 ÷ − 12.5 and − 3.7 kJ/mol, respectively). The redox-switchable outer-sphere binding of Co(III) sepulchrate via lower rim of carboxylated calix[4]arene has been revealed using cyclic voltammetry. The binding constants of outer-sphere associates based on calix[4]arenes and unstable metal complexes ([Co(sep)]2+, [Ru(bipy)3]3+, [Co(bipy)3]2+) have been calculated for the first time using 1H NMR titration and cyclic voltammetry data.

Synthesis and photophysical properties of bis(phenylpyridine) iridium(III) dicyanide complexes

Our research group is focusing on luminescence of coordination compounds which based on cyanide bridging interactions. Recently, four cyanometallate complexes based on Ir(III) complex [Ir(ppy)2(CN)2]-, which is one of an extensive family of Ir(III) complexes based on cyclometallating phenylpyridine ligands that have achieved prominence for their desirable photophysical properties, were successfully synthesised. The present study showed that, the introduction of fluorine atoms to the phenyl rings could enhance the triplet excited state energy and thus caused a blue-shift phosphorescence peak (λem = 453 nm) as shown by (PPN)[Ir(2,4-F2ppy)2(CN)2] (1) compared to that of complex without fluorine atom (PPN)[Ir(ppy)2(CN)2] (4) (λem=474 nm). However, (PPN)[Ir(3,5-F2ppy)2(CN)2] (2) shows a negligible hypsochromic shift (λem = 473 nm) in the emission. Conversely, (PPN)[Ir(4-CF3ppy)2(CN)2] (3) shows a red-shift (λem = 479 nm) compared to complex (4). These complexes, like [Ru(bipy)(CN)4]2−, have a strong emissive and high energy excited state and thus, are potentially good energy donors; and are anionic with cyanide groups, and so can form cyanide-bridged complexes with other metal and lanthanide cations.

Optimization of ultrafast reverse saturable to saturable absorption transition in Ru dioxolene complex for all-optical logic applications

A detailed theoretical analysis of reverse saturable absorption (RSA) to saturable absorption (SA) transition has been presented in Ru complex [{Ru (bipy)2}2L][PF6], with picosecond laser pulses at 532 nm wavelength. Interestingly, it is shown that an increase in pulse intensity leads to transition from RSA to SA, with increased contrast, due to strong excited-state absorption. Theoretical results are in good agreement with reported experimental results. The effect of pulse intensity, pulse width, frequency and concentration has been studied to optimize the RSA to SA transition, which has been used to design all-optical picosecond NOT, AND, OR, and the universal NAND and NOR logic gates. The designs are the first application of Ru dioxolene complex based all-optical logic gates with picosecond switch off/on time. These results show the potential of transition-metal complexes for photonic applications.

Synthesis, Characterization, and Quantum Chemical Studies of Ru(phen)2Cl2.2H2O and Ru(bipy)2Cl2.2H2O With 2,6-Diacetylpyridinedihydrazone

The mixed-ligand complexes of Ru(phen)2Cl2.2H2O and Ru(bipy)2Cl2.2H2O with 2,6-diacetylpyridinedihydrazone were prepared and characterized using elemental analyses and spectroscopic techniques. Semi-empirical (PM3) and ab initio (HF/3-21G*) methods were used for the calculations of geometries, heat of formation, binding and stabilization energies. The elemental analyses were satisfactory when compared with the calculated values. The infrared and UV-Vis spectra as well as the fragmentation patterns in the mass spectra were consistent with octahedral Ru(II) complex. The conductivity measurements confirmed the 1:2 electrolyte nature of the complexes. The theoretical studies revealed higher stabilization and binding energies for the [Ru(phen)2L]2+ species which indicated that it is thermodynamically more stable.

Parallel microdevice for high throughput analysis of levofloxacin using tris (2,2'-bipyridyl) ruthenium (II) and peroxydisulfate chemiluminescence system.

A parallel microdevice has been developed for high throughput analysis using microfluidics. The detection method is based on a chemiluminescence (CL) system based on the oxidation of tris (2,2'-bipyridyl) Ru(ll) [Ru (bipy)3(2+)] by peroxydisulfate. The device consists of a photoreactor chip and two detection chips. The sample throughput can reach up to 720 runs/h with the total reagent consumption of only 2.4 mL. The parallel microdevice was evaluated using levofloxacin (LEVO) in pharmaceutical preparations. The various factors that affect the CL signal were optimized, and the LOD was found to be 30 and 27 microg/L for the two detectors, respectively (S/N = 3), while RSD was 1.1% (n = 15) for 1.0 mg/L LEVO. Two tablet samples that contain LEVO as an active ingredient were successfully analyzed using the proposed parallel microdevice.

Dehydrogenation and demethanation of 2-methylpropane and propane in the gas-phase by the 16-electron complex [Ru(bipy)2(CO)]2+* chemically activated by the association of [Ru(bipy)2]2+ and CO

The reactions of [Ru(bipy)(2)](2+) with 2-methylpropane, propane, and propene have been investigated in the ICR cell of a mass spectrometer. In these reactions, the association of one molecule of each hydrocarbon was observed. When [Ru(bipy)(2)](2+) was ligated with CO, and the newly formed [Ru(bipy)(2)(CO)](2+) was allowed to react with 2-methylpropane and propane both dehydrogenation and demethanation were observed among association and substitution products. Density functional calculations were used to help elucidate the mechanism and the energy requirement for the dehydrogenation and demethanation reactions of 2-methylpropane mediated by [Ru(bipy)(2)(CO)](2+)*. These very interesting elimination reactions of [Ru(bipy)(2)(CO)](2+) are attributed to a hot 16-electron intermediate, [Ru(bipy)(2)(CO)](2+)*, formed upon ligation of [Ru(bipy)(2)](2+) with CO which has no efficient means of dissipating its internal energy in the low-pressure confines of the ICR cell. The reactions were concluded to occur via a concerted elimination mechanism rather than by oxidative addition/reductive elimination following the dissociation of one Ru-N bond.

A novel method of chemiluminescence detection coupled with high-performance liquid chromatography and its application in direct determination of tartaric, malic and citric acids in fruit juice

In the present work, a new method of chemiluminescence detection coupled with high performance liquid chromatography for three organic acids—tartaric, malic and citric acids is described. The detection is based on the enhancement of the organic acids for the chemiluminescence reaction between cerous sulfate (Ce(SO4)2) and tris (2,2′-bipyridyl)ruthenium(II) (Ru(bipy)32+). The latter was immobilized on the cationic ion-exchange resin for obtaining high sensitivity and reducing consumption of expensive reagent. Under the optimal conditions, the linear ranges were 7.5 × 10−7 g mL−1 to 7 × 10−6 g mL−1 for tartaric acid, 4.0 × 10−7 g mL−1 to 1.0 × 10−5 g mL−1 for malic acid and 1 × 10−7 g mL−1 to 1.5 × 10−6 g mL−1 for citric acid, and the detection limits were 1.5 × 10−7 g mL−1, 2.0 × 10−7 g mL−1, 4.0 × 10−8 g mL−1 for tartaric, malic and citric acid, respectively. The proposed method had been successfully applied to the determination of three organic acids in fruit juice – with only filtration and dilution steps.

Synthesis, photophysical, and electrochemical properties of a new family of trinuclear Ru(II) polypyridine complexes

A series of four tripodal ligands L1–4 were prepared by the reaction of 9-(2-hydroxy)phenylimino-4,5-diazafluorene with 1,3,5-tris(bromomethyl)benzene, 1,3,5-tris(bromomethyl)-2,4,6-trimethylbenzene, tris(2-chloroethyl)amine hydrochloride, and pentaerythrityl tetratosylate, respectively, in DMF solution under nitrogen. For each ligand, Ru(II) complexes were prepared by refluxing Ru(bipy)2Cl2 · 2H2O and ligand in 2-methoxyethanol. Photophysical behaviors of these Ru(II) complexes have been investigated by UV-Vis absorption and luminescence spectrometry. They display metal-to-ligand charge transfer absorption at 442 nm in MeCN solution at room temperature and emission at 574 nm in EtOH–MeOH (4 : 1, v/v) glassy matrix at 77 K. Electrochemical studies of the Ru(II) complexes show one Ru(II)-centered oxidation at 1.33 V and three ligand-centered reductions.

Sensitive detection of H2O2 and H2O2-related reactant with Ru(bipy)2(7,8-dimethyl-dipyridophenazine)2+ and oligodeoxyribonucleotide

A sensor for H(2)O(2) and H(2)O(2)-related reactant was constructed with oligonucleotides and Ru(bipy)(2)dppx(2+) (bipy = 2,2'-bipyridine, dppx = 7,8-dimethyl-dipyridophenazine), which was performed by converting the H(2)O(2)-induced DNA cleavage into the change of luminescence. The 'DNA light switch' Ru(bipy)(2)dppx(2+) could emit strong luminescence in the presence of dsDNA. DNA cleavage occurred upon addition of H(2)O(2) due to the Fenton reaction, which resulted in the decrease of the luminescence of Ru(bipy)(2)dppx(2+). Therefore, the luminescence intensity depended on the concentration of H(2)O(2) and H(2)O(2)-related reactants, and the detection limits for H(2)O(2), uric acid and cholesterol were 0.20 μM, 0.46 μM and 1.25 μM, respectively. The recovery varied between 94.0% and 105.0% when the assay was applied to the determination of uric acid and cholesterol in biological samples, which demonstrated the good practicability of the assay.

Study of CdS-ZnS Photocatalyst Loaded with Pd & Pt Embedded on Immobilized Matrix for Decomposition of Na 2 S-Na 2 SO 3 Solution by Solar Energy using Different Sacrificial Substrates and Photosensitiser

Mixed CdS-ZnS photocatalyst (1 : 4 molar ratio) and Pt, Pd loaded mixed semiconductor photocatalysts immobilized on Whatmann No. 1 fitter paper matrix were prepared. Photocatalytic production of hydrogen from Na 2 S-Na 2 SO 3 solution by immobilized photocatalyst using sacrificial agents like EDTA, oxalate, formate etc. and photosensitiser like Ru(bipy) 3 Cl 2 were studied. The maximum photoproduction of hydrogen obtain when mixed CdS-ZnS loaded with Pt (1.5 wt%) photocatalyst immobilized in Whatman No.1 filter paper matrix was used with Ru (bipy) 3 Cl 2 .

Towards an ideal method for analysis of lisinopril in pharmaceutical formulations using a tris(2,2′-bipyridyl)-ruthenium(ii)-peroxydisulfate chemiluminescence system in a two chip device

A novel, rapid, selective and sensitive method has been developed for analysis of lisinopril (LIS) in pharmaceutical formulations using a tris(2,2′-bipyridyl)-ruthenium(II) (Ru(bipy)32+) peroxydisulfate chemiluminescence (CL) system in a two chip device. The parameters that influence the CL signal intensity were carefully optimized. These include pH, flow rates and concentration of reagents used. Under optimum conditions, a linear calibration curve between 0.25 and 50.0 μg mL−1 was obtained. About 180 samples were analyzed per hour while the detection limit was found to be 0.067 μg mL−1. The method was applied for analysis of LIS in pharmaceutical products and was found to be free from interferences of acid-induced degradation (AID) products and other ingredients usually present in these preparations.

Analysis of phenylephrine hydrochloride in pharmaceutical formulations and biological fluids using (2,2′-bipyridyl)ruthenium(ii)-peroxydisulphate chemiluminescence system in a two-chip microdevice

A two-chip microdevice has been developed for the analysis of phenylephrine hydrochloride (PEH) in pharmaceutical formulations and biological fluids using (2,2′-bipyridyl)ruthenium(II) (Ru(bipy)32+)-peroxydisulphate chemiluminescence (CL) system. It was observed that a pre-derivatization step is required to obtain an analytically useful CL signal. Using 0.5 mol L−1 formaldehyde solution as derivatization reagent, eighteen-time enhancement in the CL signal was observed. The derivatization reaction, photoreaction of (Ru(bipy)32+) with peroxydisulphate to produce (Ru(bipy)33+), reaction of (Ru(bipy)33+) with the derivatization product and detection of the produced CL signal were all carried out in this two-chip microdevice using minute quantity of reagents (27 μL per run). Various parameters that influence the derivatization reaction and the CL signal intensity were optimized. These include pH, flow rates and concentration of reagents used. A linear response was observed over the range 0.25 μg mL−1 to 15.0 μg mL−1 (R2 = 0.9999) with RSD values of 0.03% (n = 15) for 1 μg mL−1. The limit of detection (LOD) was found to be 0.027 μg mL−1 (S/N = 3). The developed method was successfully applied for the analysis of PEH in biological fluids and pharmaceutical formulations.

DNA interactions of ruthenium(II) complexes with a polypyridyl ligand: 2-(2, 5-dimethoxyphenyl)-1H-imidazo[4,5-f]1,10-phenanthroline

This article describes the synthesis of a polypyridyl ligand, namely 2-(2, 5-dimethoxyphenyl)-1H-imidazo[4,5-f]1,10-phenanthroline (DMPIP) and its Ru(II) complexes, namely [Ru(bipy)2DMPIP]2+ (1), [Ru(dmb)2DMPIP]2+ (2) and [Ru(phen)2DMPIP]2+ (3) ((bipy = 2,2′-bipyridine, dmb = 4,4′-dimethyl-2,2′-bipyridine, phen = 1,10-phenanthroline). The complexes were characterized by elemental analysis, plus IR, 1H-NMR and 13C [1H]-NMR spectra. The interactions of the complexes with calf thymus DNA were investigated. The results indicate that the three complexes can intercalate into DNA. Under irradiation at 365 nm, all three complexes promote the photocleavage of plasmid pBR 322 DNA. Inhibitor studies suggest that singlet oxygen plays a significant role in the cleavage mechanism for the complexes.

DNA interaction with Ru(ii) and Ru(ii)/Cu(ii) complexes containing azamacrocycle and dppz residues. A thermodynamic, kinetic and theoretical study.

Ru(ii) complexes that bring together the properties of the dppz (dipyrido[3,2-a:2',3'-c]phenazine) intercalating residue and the properties of metal-coordinating macrocycles (L = 4,4'-(2,5,8,11,14-pentaaza[15])-2,2'-bipyridilophane) have been synthesised and their protonation and affinity for copper(ii) was analysed. Ru(bpy)(dppz)L(2+) (D2(2+)) and Ru(dppz)(2)L(2+) (D3(2+)) were found to interact with DNA but the binding mode is not simple and its features strongly depend both on the ligand structure and on the [DNA]/[complex] ratio. Equilibrium measurements (spectrophotometric and spectrofluorometric titrations), kinetics (stopped-flow technique) and theoretical calculations all concur in suggesting that for the less hindered D2(2+) an important contribution of external binding, driven by dye-dye interactions, is operative, as revealed by the onset of positive cooperativity. On the contrary, for the bulkier D3(2+) complex dye-dye interactions are less effective, resulting in an intercalation process with lower dppz penetration within DNA slots. The Ru(bipy)(2)L(2+)(D1(2+))/DNA system was also analysed for comparison and helped in showing the non negligible contribution of the macrocycle to the binding process. The binding affinities of the macrocycle copper complexes for DNA are lower than those of their copper-free analogues only in the case of D1(2+), whereas an affinity enhancement in agreement with the charge increase upon copper coordination is observed for D2(2+) and D3(2+). Copper coordination produces complete loss of the cooperative behaviour in the case of D2(2+). Further mechanistic details are discussed.

Flow-Injection Chemiluminescent Determination of Piroxicam Using Tris (2,2′-bipyridyl) Ruthenium(II)—Potassium Permanganate System

A rapid and sensitive chemiluminescence method using flow-injection has been developed for the determination of an analgesic agent drug, piroxicam. The method is based on the chemiluminescence reaction of piroxicam with an acidic potassium permanganate and Ru(bipy)3 2+. The chemiluminescence intensity is greatly enhanced when quinine sulfate is used as a sensitizer. After optimization of the different experimental parameters, a calibration graph was obtained over a concentration range of 3.0 × 0−8–3.0 × 0−5 mol L−1 with the detection limit of 1.0 × 0−8 mol L−1. The relative standard deviation is 1.5% (n = 11) for the determination of 8.0 × 10−7 mol L−1 piroxicam. The proposed method was successfully applied to commercial tablets, spiked serum, and urine samples.

Enhanced electrochemical activity of redox-labels in multi-layered protein films on indium tin oxide nanoparticle-based electrode

Facile electrical communication between redox-active labeling molecules and electrode is essential in the electrochemical detection of bio-affinity reactions. In this report, nanometer-sized indium tin oxide (ITO) particles were employed in the fabrication of porous thick film electrodes to enhance the otherwise impeded electrochemical activity of redox labels in multi-layered protein films, and to enable quantitative detection of avidin/biotin binding interaction. To carry out the affinity reaction, avidin immobilized on an ITO electrode was reacted with mouse IgG labeled with both biotin and ruthenium Tris-(2,2′-bipyridine) (Ru–bipy). The binding reaction between avidin and biotin was detected by the catalytic voltammetry of Ru–bipy in an oxalate-containing electrolyte. On sputtered ITO thin film electrode, although a single layer of Ru–bipy labeled avidin exhibited substantial anodic current, attaching the label to the outer IgG layer of the avidin/biotin–IgG binding pair resulted in almost complete loss of the signal. However, electrochemical current was recovered on ITO film electrodes prepared from nanometer-sized particles. The surface of the nanoparticle structured electrode was found by scanning electron microscopy to be very porous, and had twice as much surface binding capacity for avidin as the sputtered electrode. The results were rationalized by the assumption of different packing density of avidin inner layer on the two surfaces, and consequently different electron transfer distance between the electrode and Ru–bipy on the IgG outer layer. A linear relationship between electrochemical current and IgG concentration was obtained in the range of 40–4000 nmol L −1 on the nanoparticle-based electrode. The approach can be employed in the electrochemical detection of immunoassays using non-enzymatic redox labels.

Synthesis, characterization, and catalytic properties of some new ruthenium(II)/(III) complexes containing N,N-donor ligands

This article describes the preparation and characterization of cis-[Ru(bipy)2L](ClO4)2 and trans-[RuCl2L2] · Cl (bipy = 2,2′-bipyridyl and L = ortho-phenylenediamine (o-phd), 2-aminopyridine (2-apy) and 2-aminobenzonitrile (2-abn), and examines the catalytic oxidations of benzyl alcohol, benzohydrol and pipronyl alcohol by cis-[Ru(bipy)2 (o-phd)](ClO4)2 and trans-[RuCl2(o-phd)2] · Cl complexes at room temperature and in the presence of N-methyl morpholine-N-oxide (NMO) as co-oxidant.

Synthesis, structure and physical properties of nickel bis(dithiolene) complexes with different cations

A series of new complexes of multi-sulfur 1,2-dithiolene ligands, [Ru(bipy)3][Ni(L)2]2 (bipy = 2,2′-bipyridine; L = pddt (6,7-dihydro-5H-1,4-dithiepin-2,3-dithiolate), dddt (5,6-dihydro-1,4-dithiin-2,3-dithiolate)), have been synthesized and characterized. One typical complex, [Ru(bipy)3][Ni(pddt)2]2·2H2O (1), crystallized in an acentric space group of P212121, with the cell dimensions of a = 8.634(1), b = 14.560(1), c = 49.889(5) Å, α = β = γ = 90°, and Z = 4. It consists of alternating columns of cations and anions along the a direction. The structure was refined by full matrix least squares methods to R 1 = 0.0340, wR 2 = 0.0670. Magnetic studies on [Ph2Cr][Ni(dddt)2] are also reported.

Kinetics and mechanism of the oxidation of glyoxylic acid by peroxodisulfate induced by irradiation with visible light of aqueous solutions containing tris (2,2‘-bypyridine)ruthenium(II) ion

The kinetics of light-induced oxidation of glyoxylic acid in the presence of [Ru(bipy) 2 + 3 ] as photo-catalyst have been studied. The observed kinetic rate law is given by -d[S 2 O 2 - 8 ]/dt = k q / a Φ[S 2 O 2 - 8 ]/k 0 +K q [S 2 O 2 - 8 ] The reaction events are governed by the following scheme. Formula Chem.

Optical properties of Ru(bipy)2(dppx)2+ in different environments

The emission spectra of Ru(bipy)2 (dppx)2+ in different environments has been studied. It was found that the solvent polarity and the ability of donating and transferring proton are the important factors in predicting luminescence intensity in different systems. The increasing content of water in the organic solutions of Ru(bipy)2 (dppx)2+ leads to decrease in emission intensity that follows the Perrin sphere of quenching model. The effect of base content of DNA on the fluorescence spectra of Ru (bipy)2 (dppx)2+ has also been studied.