Novel luminescent iminephosphine complex of copper(I) with high photochemical and electrochemical stability

Luminescent heteroleptic Cu-I complexes based on asymmetrical iminephosphine ligands exhibit improved electrochemical and photochemical stability as compared to the analogous complexes based on traditional diimine or diphosphine ligands.

Electrochemiluminescence detection of NADH and ethanol based on partial sulfonation of sol-gel network with gold nanoparticles

We developed a stable, sensitive electrochemiluminescence (ECL) biosensor based on the synthesis of a new sol-gel material with the ion-exchange capacity sol-gel to coimmobilize the Ru(bpy)(3)(2+) and enzyme. The partial sulfonated (3-mercaptopropyl)-trimethoxysilane sol-gel (PSSG) film acted as both an ion exchanger for the immobilization of Ru(bpy)(3)(2+) and a matrix to immobilize gold nanoparticles (AuNPs). The AuNPs/PSSG/Ru(bpy)(3)(2+) film modified electrode allowed sensitive the ECL detection of NADH as low as 1 nM. Such an ability of AuNPs/PSSG/Ru(bpy)(3)(2+) film to promote the electron transfer between Ru(bpy)(3)(2+) and the electrode suggested a new, promising biocompatible platform for the development of dehydrogenase-based ECL biosensors. With alcohol dehydrogenase (ADH) as a model, we then constructed an ethanol biosensor, which had a linear range of 5 mu M to 5.2 mM with a detection limit of 12 nM.

Selective hydrogenation of maleic anhydride to gamma-butyrolactone in supercritical carbon dioxide

The reaction rates of the hydrogenation of maleic anhydride (MAH) and succinic anhydride (SAH) were significantly accelerated and the selectivity to gamma-butyrolactone (GBL) was enhanced largely when the reaction mixture was pressurized by a non-reactant of CO2. Above 99% selectivity to GBL was achieved in 14 MPa CO2, the superior selectivity in scCO(2) was attributed to that MAH and/or SAH could be extracted to CO2 phase and separated from H2O, the hydrolysis were thus minimized and so the selectivity to GBL was improved.

Solid-state electrochemiluminescence sensor based on the Nafion/poly(sodium 4-styrene sulfonate) composite film

An effective electrochemiluminescence (ECL) sensor based on Nafion/poly(sodium 4-styrene sulfonate) (PSS) composite film-modified ITO electrode was developed. The Nafion/PSS/Ru composite film was characterized by atomic force microscopy, UV-vis absorbance spectroscopy and electrochemical experiments. The Nafion/PSS composite film could effectively immobilize tris(2,2'-bipyridyl)ruthenium(II) (Ru(bpy)(3)(2+)) via ion-exchange and electrostatic interaction. The ECL behavior of Ru(bpy)(3)(2+) immobilized in Nafion/PSS composite film was investigated using tripropylamine (TPA) as an analyte. The detection limit (S/N = 3) for TPA at the Nafion/PSS/Ru composite-modified electrode was estimated to be 3.0 nM, which is 3 orders of magnitude lower than that obtained at the Nafion/Ru modified electrode. The Nafion/PSS/Ru composite film-modified indium tin oxide (ITO) electrode also exhibited good ECL stability. In addition, this kind of immobilization approach was simple, effective, and timesaving.

Tuning the Energy Level of Organic Sensitizers for High-Performance Dye-Sensitized Solar Cells

Cost-effective organic sensitizers will play a pivotal role in the future large-scale production and application of dye-sensitized solar cells. Here we report two new organic D-pi-A dyes featuring electron-rich 3,4-ethylenedioxythiophene- and 2,2'-bis(3,4-ethylenedioxythiophene)-conjugated linkers, showing a remarkable red-shifting of photocurrent action spectra compared with their thiophene and bithiophene counterparts. On the basis of the 3-f{5'-[N,N-bis(9,9-dimethylfluorene-2-yl)phenyl]-2,2'-bis(3,4-ethylenedioxythiophene)-5-yl}2-cyanoacrylic acid dye, we have set a new efficiency record of 7.6% for solvent-free dye-sensitized solar cells based on metal-free organic sensitizers. Importantly, the cell exhibits an excellent stability, keeping over 92% of its initial efficiency after 1000 h accelerated tests under full sunlight soaking at 60 degrees C. This achievement will considerably encourage further design and exploration of metal-free organic dyes for higher performance dye-sensitized solar cells.

Conjugation of Selenophene with Bipyridine for a High Molar Extinction Coefficient Sensitizer in Dye-Sensitized Solar Cells

A high molar extinction coefficient heteroleptic polypyridyl ruthenium sensitizer, featuring a conjugated electron-rich selenophene unit in its ancillary ligand, has been synthesized and demonstrated as an efficient sensitizer in dye-sensitized solar cells. A nanocrystalline titania film stained with this sensitizer shows improved optical absorptivity, which is highly desirable for dye-sensitized solar cells with a thin photoactive layer. With preliminary testing, this sensitizer has already achieved a high efficiency of 10.6% measured under the air mass 1.5 global conditions.

Formation of [Ru(bpy)(3)](2+)-containing microstructures induced by electrostatic assembly and their application in solid-state detection of electrochemiluminescence

Tris(2,2'-bipyridine)ruthenium(II) ((Ru(bpy)(3)](2+)) is one of the most extensively studied and used electrochemiluminescent (ECL) compounds owing to its superior properties, which include high sensitivity and stability under moderate conditions in aqueous solution. In this paper we present a simple method for the preparation of [Ru(bpy)(3)](2+)-containing microstructures based on electrostatic assembly The formation of such micro-structures occurs in a single process by direct mixing of aqueous solutions of [Ru(bpy)(3)]Cl-2 and K-3[Fe(CN)(6)] at room temperature. The electrostatic interactions between [Ru(bpy)(3)]Cl-2 cations and [Fe(CN)(6)](3-) anions cause them to assemble into the resulting microstructures. Both the molar ratio and concentration of reactants were found to have strong influences on the formation of these microstructures. Most importantly, the resulting [Ru(bpy)(3)](2+)- containing microstructures exhibit excellent ECL behavior and, therefore, hold great promise for solid-state ECL detection in capillary electrophoresis (CE) or CE microchips.

Polyethyleneimine-Functionalized Platinum Nanoparticles with High Electrochemiluminescence Activity and Their Applications to Amplified Analysis of Biomolecules

Polyethyleneimine-functionalized platinum nanoparticles (PtNPs) with excellent electrochemiluminescence (ECL) properties were synthesized and applied to the amplified analysis of biomolecules. These particles were prepared at room temperature, with hyperbranched polyethyleneimine (HBPEI) as the stabilizer. The UV/Vis absorption spectra and transmission electron microscopy images clearly confirmed the formation of monodisperse PtNPs. Such particles proved to possess high stability against salt-induced aggregation, enabling them to be employed even under high-salt conditions. Owing to the existence of many tertiary amine groups, these particles exhibited excellent ECL behavior in the presence of tris(2.2'-bipyridyl)ruthenium(II). An HBPEI-coated particle possessed an ECL activity that was at least 60 times higher than that of a tripropylamine molecule. Furthermore, these particles could be immobilized on the 3-aminopropyltriethoxysilane-treated quartz substrates to amplify the binding sites for carboxyl groups. Through this approach, PtNPs were applied to the amplified analysis of the hemin/G-quadruplex DNAzyme by using the luminol/H2O2 chemiluminescence method.

Electrochemiluminescence sensor based on partial sulfonation of polystyrene with carbon nanotubes

Herein, homogenously partial sulfonation of polystyrene (PSP) was performed. An effective electrochemiluminescence (ECL) sensor based on PSP with carbon nanotube (CNTs) composite film was developed. Cyclic voltammetry and electrochemical impendence spectroscopy were applied to characterize this composite film. The PSP was used as an immobilization matrix to entrap the ECL reagent Ru(bpy)(3)(2+) due to the electrostatic interactions between sulfonic acid groups and Ru(bpy)(3)(2+) cations. The introduction of CNTs into PSP acted not only as a conducting pathway to accelerate the electron transfer but also as a proper matrix to immobilize Ru(bpy)(3)(2+) on the electrode by hydrophobic interaction. Furthermore, the results indicated the ECL intensity produced at this composite film was over 3-fold compared with that of the pure PSP film due to the electrocatalytic activity of the CNTs. Such a sensor was verified by the sensitive determinations of 2-(dibutylamino)ethanol and tripropylamine.

Characterization of procaine metabolism as probe for the butyrylcholinesterase enzyme investigation by simultaneous determination of procaine and its metabolite using capillary electrophoresis with electrochemiluminescence detection

Capillary electrophoresis with electrochemiluminescene detection was used to characterize procaine hydrolysis as a probe for butyrylcholinesterase by in vitro procaine metabolism in plasma with butyrylcholinesterase acting as bioscavenger. Procaine and its metabolite N,N-diethylethanolamine were separated at 16 kV and then detected at 1.25 V in the presence of 5.0 mM Ru(bpy)(3)(2+), with the detection limits of 2.4 x 10(-7) and 2.0 x 10(-8) mol/L (S/N=3), respectively. The Michaelis constant K-m value was 1.73 x 10(-4) mol/L and the maximum velocity V-max was 1.62 x 10(-6) mol/L/min. Acetylcholine bromide and choline chloride presented inhibition effects on the enzymatic cleavage of procaine, with the 50% inhibition concentration (IC50) of 6.24 x 10(-3) and 2.94 x 10(-4) mol/L.

A novel sensitive solid-state electrochemiluminescence sensor material: Ru(bpy)(2+)(3) doped SiO2@MWNTs coaxial nanocable

A simple, large scale, and one-step process for the preparation of tris(2,2'-bipyridyl)ruthenium(I) (Ru(bpy)(3)(2+)) doped SiO2@carbon nanotubes (MVNTs) coaxial nanocable used for an ultrasensitive electrochemiluminescence (ECL) is presented for the first time. More importantly, a directly coated as-formed functional material on ITO electrode surface exhibits excellent ECL behavior, good stability, and high sensitivity in the presence of tripropylamine (TPA). This novel functional material will find potential applications in biosensor, electrophoresis and electroanalysis.

One-step synthesis of Ru(2,2 '-bipyridine)(3)Cl-2-immobilized silica nanoparticles for use in electrogenerated chemiluminescence detection

One-step synthesis of Ru (bpy)(3) Cl-2-immobilized (bpy = 2,2'-bipyridine) silica nanoparticles (Ru-silica nanoparticles) for use in electrogenerated-chemiluminescence (ECL) detection is reported. Ru-silica nanoparticles are prepared by using the Stober method. Compared with free Ru(bpy)(3)Cl-2, Ru-silica nanoparticles are seen to exhibit a red-shift of the UV-vis absorbance peak and a longer fluorescence lifetime, which are attributed to the electrostatic interaction of Ru(bpy)(3)(2+) and silica. Because silica nanoparticles are used as immobilization matrices, the surfaces of Ru-silica nanoparticles are easily modified or functionalized via the assembly of other nanoparticles, such as Au. For ECL detection, Au-colloid-modified Ru-silica nanoparticles are immobilized on a 3-mercaptopropyl-trimethoxysilane-modified indium tin oxide electrode surface by Au-S interaction; the surface concentration of electroactive Ru(bpy)(3)Cl-2 is obviously higher than that in silica films.

A novel alcohol dehydrogenase biosensor based on solid-state electrogenerated chemiluminescence by assembling dehydrogenase to Ru(bpy)(3)(2+)-Au nanoparticles aggregates

Based on electrogenerated chemiluminescence (ECL), a novel method for fabrication of alcohol dehydrogenase (ADH) biosensor by self-assembling ADH to Ru(bpy)(3)(2+) -AuNPs aggregates (Ru-AuNPs) on indium tin oxide (ITO) electrode surface has been developed. Positively charged Ru(bpy)(3)(2+) could be immobilized stably on the electrode surface with negatively charged AuNPs in the form of aggregate via electrostatic interaction. On the other hand, AuNPs are favourable candidates for the immobilization of enzymes because amine groups and cysteine residues in the enzymes are known to bind strongly with AuNPs. Moreover, AuNPs can act as tiny conduction centers to facilitate the transfer of electrons. Such biosensor combined enzymatic selectivity with the sensitivity of ECL detection for quantification of enzyme substrate, and it displayed wide linear range, high sensitivity and good stability.

Charge carrier transporting, photoluminescent, and electroluminescent properties of zinc(II)-2-(2-hydroxyphenyl)benzothiazolate complex

Zinc(II)-2-(2-hydroxyphenyl)benzothiazolate complex is an excellent white-light-emitting material. Despite some studies devoted to this complex, no information on the real origin of the unusually broad electroluminescent (EL) emission is available. Therefore, we investigate photoluminescent and EL properties of the zinc complex. Orange phosphorescent emission at 580 nm was observed for the complex in thin film at 77 K, whereas only fluorescent emission was obtained at room temperature. Molecular orbitals, excitation energy, and emission energy of the complex were investigated using quantum chemical calculations. We fabricated the device with a structure of ITO/F16CuPc(5.5 nm)/Zn-complex/Al, where F16CuPc is hexadecafluoro copper phthalocyanine. The EL spectra varied strongly with the thickness of the emissive layer. We observed a significant change in the emission spectra with the viewing angles. Optical interference effects and light emission originating both from fluorescence and from phosphorescence can explain all of the observed phenomena, resulting in the broad light emission for the devices based on the Zn complex. We calculated the charge transfer integral and the reorganization energy to explain why the Zn complex is a better electron transporter than a hole transporter.

Selective hydrogenation of citral with transition metal complexes in supercritical carbon dioxide

The activity and selectivity of the transition metal complexes formed from Ru, Rh, Pd and Ni with triphenylphosphine (TPP) have been investigated for hydrogenation of citral in supercritical carbon dioxide (scCO(2)). High activities are obtained with Ru/TPP and Pd/TPP catalysts, and the overall activity is in the order of Pd approximate to Ru > Rh > Ni. The Ru/TPP complex is highly selective to the formation of unsaturated alcohols of geraniol and nerol. In contrast, the Pd/TPP catalyst is more selective to partially saturated aldehydes of citronellal. Furthermore, the influence of several parameters such as CO2 and H-2 pressures, N-2 pressure and reaction time has been discussed. CO2 pressure has a significant impact on the product distribution, and the selectivity for geraniol and nerol can be enhanced from 27% to 75% with increasing CO2 pressure from 6 to 16 MPa, while the selectivity for citronellol decreases from 70% to 20%. Striking changes in the conversion and product distribution in scCO(2) could be interpreted with variations in the phase behavior and the molecular interaction between CO2 and the substrate in the gas phase and in the liquid phase.