Studies of perchlorate triggered ion-gate behavior of sBLM by electrochemiluminescence and its application to a sensor for perchlorate

Ru(bpy)(3)(2+) electrochemiluminescence (ECL) method and electrocatalysis method were first used to study the ion-gate behavior of supported lipid bilayer membrane (sBLM). We found that sBLM, made of dimethyldioctadecylammonium bromide (a kind of synthetic lipid), showed ion-gate behavior for the permeation of Ru(bpy)(3)(2+) in the presence of perchlorate anion. There existed a threshold concentration (0.1 muM) of perchlorate anion for ion-gate opening. Below the threshold the ion-gate was closed. Above the threshold, the number of opened ion-gate sites increased with the increase of perchlorate anion concentration and leveled off at concentrations higher than 1200 muM. Based on it, a new sensor for perchlorate was developed. Furthermore, the opening and closing of the ion-gate behavior was reversible, which means the sensor can repeatedly be used.

Synthesis, characterization, determination of luminescent properties of tetracoordinate organoboron compounds derivatives from organic tridentate ligands, and their potential application in OLEDs.

Tesis (Doctor of Science with orientation in Materials Chemistry) UANL, 2014.

Sensitive luminescent paper-based sensor for the determination of gaseous hydrogen sulfide

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Determination of isocyanates by capillary electrophoresis with tris(2,2 '-bipyridine) ruthenium(II) electrochemiluminescence

CE with tris(2,2'-bipyridyl) ruthenium(II) (Ru(bpy)(3)(2+)) electrochemiluminescence (ECL) detection for the quantitative determination of isocyanates was first reported. Hexamethylene diisocyanate (HDI) and hexyl isocyanate (HI) were used as the model analytes. Commercially available N,N-diethyl-N'-methylethylenediamine was used as the derivatization reagent. It has both a secondary amine group and a tertiary amine group. The secondary amine group can quantitatively react with isocyanate group, and the tertiary amine group can react with Ru(bpy)(3)(2+) to produce strong ECL signal for sensitive detection. The derivatization reaction was almost instantaneous and is much faster than other reported derivative reactions using other derivative reagents.

A novel tris(2,2 '-bipyridine)ruthenium(II)/tripropylamine cathodic electrochemiluminescence in acetonitrile for the indirect determination of hydrogen peroxide

A novel tris(2,2'-bipyridine)ruthenium(II) (Ru(bpy)3(2+)) cathodic electrochemiluminescence (ECL) was generated at -0.78V at the Pt electrode in acetonitrile (ACN), which suggested that the cathodic ECL differed from conventional cathodic ECL It was found that tripropylamine (TPrA) could enhance this cathodic ECL and the linear range (log-log plot) was 0.2 mu M-0.2 mM. In addition, hydrogen peroxide (H2O2) could inhibit the cathodic ECL and was indirectly detected with the linear range of 27-540 mu M. The RSD (n = 12) of the ECL intensity in the presence of 135 mu M H2O2 was 0.87%. This method was also demonstrated for the fast determination of H2O2 in disinfectant sample and satisfactory results were obtained.

Controlled Synthesis of Ln(3+) (Ln = Tb, Eu, Dy) and V5+ Ion-Doped YPO4 Nano-/Microstructures with Tunable Luminescent Colors

YPO4 nano/microcrystals with multiform crystal phases and morphologies, such as hexagonal nano/submicroprisms, spherical-like nanoparticles, and nanorods with different length/diameter ratios as well as tetragonal nanospindles, have been synthesized via a facile hydrothermal route. A series of controlled experiments indicate that the pH values in the initial solution, phosphorus sources, and the organic additive trisodium citrate (Cit(3-)) are responsible for crystal phase and shape determination of final products. It is found that Cit(3-) as a ligand and shape modifier has the dynamic effect by adjusting the growth rate of different facets under different experimental conditions, resulting in the formation of various geometries of the final products. The possible formation mechanisms for products with diverse architectures have been presented.

Determination of sulpiride by capillary electrophoresis with end-column electrogenerated chemiluminescence detection

Background: Capillary electrophoresis (CE) with tris(2,2'-bipyridyl)ruthenium(II) [Ru(bpy)(3)(2+)]-electro-generated chemiluminescence (ECL) detection is a promising method for clinical analysis. In this study, a method combining CE with Ru(bpy)(3)(2+) ECL (CE-ECL) detection that can be applied to amine-containing clinical species was developed, and the performance of CE-ECL as a quantitative method for determination of sulpiride in human plasma or urine was evaluated. Methods: Sulpiride was separated by capillary zone electrophoresis in uncoated fused-silica capillaries [510 cm x 25 mum (i.d.)] filled with phosphate buffer (pH 8.0 and a driving voltage of +15 kV, with end-column Ru(bpy)(3)(2+) ECL detection. A platinum disc electrode was used as working electrode. Sulpiride in human plasma or urine samples (100 muL) was extracted by a double-step liquid-liquid extraction procedure, dried under nitrogen at 35 degreesC in a water bath, and reconstituted with 100 muL of filtered water. The extraction solvent was ethyl acetate-dichloromethane (5:1 by volume). Results: Under optimum conditions (pH 8.0 phosphate buffer, injection for 6 s at 10 kV, and +1.2 V as detection potential), separation of sulpiride was accomplished within 4 min. The calibration curve was linear over a concentration range of 0.05-25.0 mumol/L, and the limit of detection was 2.9 x 10(-8) mol/L for sulpiride. Intra- and interday CVs for ECL intensities were <6%. Extraction recoveries of sulpiride were 95.6-101% with CVs of 2.9-6.0%. The method was,clinically validated for patient plasma and urine samples. Conclusions: CE combined with Ru(bpy)(3)(2+) ECL is reproducible, precise, selective, and enables the analysis of sulpiride in human plasma and urine. It thus is of value for rapid and efficient analysis of amine-containing analytes of clinical interest.

Luminescent properties of Langmuir-Blodgett films of europium bisphthalocyanine

Eu(III)-octa-4-(tetrahydrofurfuroxy) phthalocyanine (EuPc2') was synthesied and characterized by elementary analysis, IR, MS, UV-vis spectra. EuPc2' has good film-forming ability from determination of isotherm of pi-A. The complex LB film was formed by depositing of EuPc2' on a quartz slide with the LB techniques of the Z-type, The luminescent properties of pure and doped LS films were determined. The results showed that pure films have good luminescent properties, the thicker the LB films, the stronger the fluorescent intensity. The films doped with o-phenanthroline (abbreviated as phen) made the relative intensity of fluorescent emission behavior enhance in comparison to that of pure LB film, But the amount of phen may be not too much. Our results showed that EuPc2':phen = 1: 10 (molar ratio) has the best fluorescent behavior. The electronic spectroscopic characterization of the LB films is also given.

Electrochemiluminescent determination of peroxydisulfate with Cr(bpy)(3)(3+) in purely aqueous solution

A novel method for the sensitive and selective determination of peroxydisulfate was proposed. It was based on an electrochemiluminescent method with Cr(bpy)(3)(3+). The applied potential was set at -0.5 V in Cr(bpy)(3)(3+) system which was much more positive than those in Ru(bpz)(3)(2+) and Ru(bpy)(3)(2+) systems. A linear calibration was obtained over the range of 7-100 mu mol l(-1) with a correlation coefficient of 0.993. The relative standard deviation was 2% for 10 replicate injections of 0.01 mol l(-1) S2O82- solution. The detection limit (S/N=3) was 1 mu mol l(-1). The method was successfully applied to determination of peroxydisulfate in phase transfer catalysis. (C) 2000 Elsevier Science B.V. All rights reserved.

Chemiluminescent determination of luminol and hydrogen peroxide using hematin immobilized in the bulk of a carbon paste electrode

A new method for immobilization of a chemiluminescent reagent is presented. It is based on immobilizing hematin, a catalyst for luminol reaction, in the bulk of a carbon paste electrode. Bulk-immobilization allows renewal of the surface by simple polishing or cutting to expose anew and fully active surface in the case of fouling or deactivation by other means. By using a hematin-modified carbon paste electrode, the applied potential shifted negatively compared with that of unmodified carbon paste electrode or a glassy carbon electrode. The shift in potential changed the reaction processes and effectively stabilized the chemiluminescent signal during successive measurements. Under this condition, the signal was stable during 3 hours of continuous operation. The log-log plots of the emitted light intensity vs. luminol concentration and hydrogen peroxide concentration were linear over the region 10(-8)-10(-3) mol L-1 with a correlation coefficient of 0.999 and 3.9 x 10(-6)-10(-3) mol L-1 with a correlation coefficient of 0.994, respectively. Application of this method for other chemiluminescent and bioluminescent systems is suggested.

Chemiluminescent determination of glucose with a modified carbon paste electrode

A flow injection analysis detection method for glucose is presented which is based on the oxidation of glucose by glucose oxidase followed by chemiluminescent detection of hydrogen peroxide. Both glucose oxidase and hematin, a chemiluminescent reaction catalyst, were bulk-immobilized conveniently by direct mixing with carbon paste, which allows renewal of the electrode surface by simply polishing or cutting to expose a new and fully active surface in the case of fouling. Luminol in reagent solution passed through the flow cell and reacted with hydrogen peroxide produced by the enzyme reactor in the presence of the catalyst to yield light. An applied potential of -0.4 V avoided the electrode fouling effectively. The log-log plot of the emitted light intensity vs glucose concentration was linear over the range of 1-100 mmol L-1 with a correlation coefficient of 0.992. Application of this method to other chemiluminescent and bioluminescent systems is suggested. (C) 1999 Academic Press.

Listening to lanthanide complexes: Determination of the intrinsic luminescence quantum yield by nonradiative relaxation

The photophysical properties of lanthanide complexes have been studied extensively; however, fundamental parameters such as the intrinsic quantum yield as well as radiative and nonradiative decay rates are difficult or even impossible to measure experimentally. Herein, a photoacoustic (PA) method is proposed to determine the intrinsic quantum yield of lanthanide complexes with lifetimes in the order of milliseconds. This method is used to determine the intrinsic quantum yields for europium (III)-containing metallomesogens as well as terbium(III) complexes. The results show that the PA signal is sensitive to both the lifetime and the ratio of the fast-to-slow heat component of the samples. It is found that there is an efficient ligand sensitization and a moderate intrinsic quantum yield for the complexes. The intrinsic quantum yield of Eu3+ in the metallomesogens exhibits an obvious increase upon the isotropic liquid to smectic A transition. The proposed PA method is quite simple, and con contribute to a clearer understanding of the photophysical processes in luminescent lanthanide complexes.

Energy yield determination of concentrator solar cells using laboratory measurements

The annual energy conversion efficiency is calculated for a four junction inverted metamorphic solar cell that has been completely characterized in the laboratory at room temperature using measurements fit to a comprehensive optoelectronic model of the multijunction solar cells. A simple model of the temperature dependence is used redict the performance of the solar cell under varying temperature and spectra characteristic of Golden, CO for an entire year. The annual energy conversion efficiency is calculated by integrating the predicted cell performance over the entire year. The effects of geometric concentration, CPV system thermal characteristics, and luminescent coupling are ighlighted.

Determination of the cytotoxic capacity of organotin compounds derivatives from salicylidene benzoylhidrazone

The successful application of metal complexes in the treatment of many diseases, including cancer, is a rapidly expanding area in biomedical chemistry and research. Organotin compounds studies show the versatility and the attractive features of these molecules. In the same manner, has been reported the development of new compounds derivative from bezoylhidrazones, which possess the azomethine fragment (-N = CH-), key pillar for designing new drugs with biological activity. Based on the above, we are interested in to synthesize four tin compounds derivatives from benzoylhidrazones, and the evaluation of their cytotoxic capacity. Conclusions and contribution: In this research work, we reported four new tin compounds derivatives from bezoylhidrazones, which were characterized by spectroscopic and spectrometric techniques and X-ray diffraction In the same manner, cytotoxic ability of each compound was studied and reported and compared with metaled base drugs like cisplatin and carboplatin. Also, in some cases it was possible to use their luminescent ability to study their intracellular behavior.

Determination of preventive maintenance lead time using hybrid analysis

The time for conducting Preventive Maintenance (PM) on an asset is often determined using a predefined alarm limit based on trends of a hazard function. In this paper, the authors propose using both hazard and reliability functions to improve the accuracy of the prediction particularly when the failure characteristic of the asset whole life is modelled using different failure distributions for the different stages of the life of the asset. The proposed method is validated using simulations and case studies.