Photoluminiscence response of Ru(II) complex immobilized in SiO2-based matrix to dissolved oxygen in beer (original) (raw)
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Journal of Non-Crystalline Solids, 2008
Films are deposited by dip-or spin-coating in gels produced from tetraethoxysilane (TEOS), octyltriethoxysilane (OtEOS) or mixtures of TEOS and OtEOS (mole ratio1:1) as well as TEOS and methyltriethoxysilane (MtEOS) (mole ratio 1:3). The Stern-Volmer constants and the response to oxygen of Ru(II)-tris(4,7-diphenyl-1,10-phenathroline) dichloride immobilized in the produced matrices are calculated. The oxygen sensitivity of the film depends on the chemical nature of the precursors, the Ru(II) concentration, the film deposition technology, and the film thickness. The uncertainty of the results obtained with films of different production batches varies between 1.5% and 3% of the measured value for oxygen content for gas mixtures between 10% and 90% oxygen content. The sonication of the sol has a strong positive effect on the sensitivity of the films and the linearity of the calibration curves.
Electroanalysis, 2003
Ru(II) tris-bipyridine based ECL sensors were produced by embedding the complex inside silica glass thin films deposited via a sol-gel dipping procedure on K-glass conducing substrates. Films were prepared starting from a prehydrolyzed ethanolic solution of Si(OC 2 H 5 ) 4 and Ru(bpy) 3 Cl 2 . Transparent, crack-free and homogeneous reddish silica layers, having a thickness of 200 AE 20 nm, were obtained. The films, either deposited at room temperature or thermally annealed at 100, 200 and 300 8C for 30 h, were structurally and chemically characterized. Ru(bpy) 3 Cl 2 thermal stability was previously checked by thermogravimetric analysis (TGA). The films were investigated by X-Ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS) and UV-vis spectroscopy. XPS in-depth profiles revealed a homogeneous distribution of the ruthenium complex inside the silica thin layers. SIMS data suggested that the embedded Ru(bpy) 3 Cl 2 did not react with oxygen inside the oxygen-rich silica matrix to give Ru-O bonds. Electrochemical and ECL characterization of the thin film electrodes were made by means of cyclic voltammetry (CV) and controlled potential step experiments. The ECL sensor showed a diffusive redox behavior of the Ru(bpy) 3 2 /Ru(bpy) 3 3 system. Light emission produced from the reaction between oxalic acid and the electrogenerated Ru(bpy) 3 3 was larger and stable when thermally treated electrodes were used after a suitable hydration period. The 300 8C treated sample was the best performing sensor both in terms of low complex leakage and sensitivity. Calibration plots relative to oxalic acid were obtained both in stationary and in flowing solutions in the concentration range 2 Â 10 À6 À 3 Â 10 À4 M. A linear behavior appeared in the former case, while in the latter a slight curvature was evident as a consequence of a finite diffusion time of the analyte inside the thin film. The signal repeatability, obtained by multiple 100 mL of 10 À5 M oxalic acid injections in flowing solutions, was better than 4%. The obtained detection limit (computed as three times the standard deviation of the base-line noise) was 10 À6 M as oxalic acid.
Chemistry of Materials, 2004
The title compounds were synthesized by Sonogashira coupling reactions of appropriate Ru(II) complexes with the electron acceptors. Characterization was conducted in solution and in frozen matrixes. Finally, the title compounds were evaluated as dopants of sol-gel materials. It was found that the intramolecular quenching efficiency of 4-benzoyl-Nmethylpyridinium cation in solution depends on the solvent: photoluminescence is quenched completely in CH 3 CN, but not in methanol or ethanol. On the other hand, intramolecular emission quenching by 4-benzyl-N-methyl viologen is complete in all solvents. The difference between the two quenchers is traced electrochemically to the solvation of the 4-benzoyl-Nmethylpyridiniums by alcohol. In frozen matrixes or adsorbed on the surfaces of silica aerogel, both Ru(II) complex/electron acceptor dyads of this study are photoluminescent, and the absence of quenching has been traced to the environmental rigidity. When doped aerogels are cooled at 77 K, the emission intensity increases by ∼4×, and the spectra shift to the blue, analogous to what is observed with Ru(II) complexes in solutions undergoing fluidto-rigid transition. However, in contrast to frozen solutions, the luminescent moieties in the bulk of aerogels kept at low temperatures are still accessible to gas-phase quenchers diffusing through the mesopores, leading to more sensitive platforms for sensors than other room-temperature configurations. Thus, the photoluminescence of our Ru(II) complex dyads adsorbed on aerogel is quenchable by O 2 both at room temperature and at 77 K. Furthermore, it was also found that O 2 modulates the photoluminescence of aerogels doped with 4-benzoyl-N-methylpyridinium -based dyads over a wider dynamic range compared with aerogels doped with either our viologen-based dyads or with Ru(II) tris(1,10-phenanthroline) itself.
Optical Sol-Gel-Based Dissolved Oxygen Sensor: Progress Towards a Commercial Instrument
Journal of Sol-gel Science and Technology - J SOL-GEL SCI TECHNOL, 1998
A dissolved oxygen sensor based on fluorescence quenching of the oxygen-sensitive ruthenium complex, [Ru(II)-tris(4,7-diphenyl-1,10-phenanthroline]2+, which has been immobilized in a porous silica sol-gel-derived film, is reported. Ormosil sensing films were fabricated using modified silica precursors such as methyltriethoxysilane (MTEOS) and ethyltriethoxysilane (ETEOS) and were dip-coated onto planar glass substrates. Tailoring of the films for dissolved oxygen (DO) sensing is described whereby sensor response is optimized by maximizing film hydrophobicity by the use of the modified precursors. Sensor performance parameters such as limit of detection and sensor resolution are reported. Issues such as dye leaching and photobleaching are discussed. Progress towards a commercial instrument is reported.
Optimisation of sol-gel-derived silica films for optical oxygen sensing
Journal of Sol-Gel Science and Technology, 1997
Sol-gel-derived silica films were fabricated by dip-coating onto planar and optical fibre substrates. The films were pre-doped with the oxygen-sensitive ruthenium complex [Ru(II)-tris(4,7-diphenyl-1,10-phenanthroline)], whose fluorescence is quenched in the presence of oxygen. The structure and behaviour of sol-gel films is related to the fabrication parameters. In order to optimise the films for oxygen sensing in gaseous and in aqueous media, the quenching behaviour was monitored as a function of dip-speed and water : precursor ratio. By adjusting the above parameters, film properties can be tailored to optimise oxygen quenching in particular concentration ranges and environments.
Analytica Chimica Acta, 2010
This paper describes the fabrication and performance of a range of highly sensitive luminescence-based oxygen sensor films based on the fluorinated sol-gel precursor 3,3,3-trifluoropropyltrimethoxysilane (TFP-TMOS). The oxygen-sensitive ruthenium complex [Ruthenium(II)-tris(4,7-diphenyl-1,10phenanthroline)] dichloride, [Ru(dpp) 3 ] 2+ was entrapped in a wide range of ORMOSILs (organically modified silicates) matrices composed of alkyl and TFP-TMOS sol-gel precursors in different relative ratios. The influence of TFP-TMOS on sensor sensitivity, humidity-sensitivity and long-term stability was investigated and performance was compared to that of similar but non-fluorinated films. The optimum limit of detection was found to be 0.002% of oxygen for the propyltriethoxysilane (PTEOS)/TFP-TMOS-derived film compared to 0.09% for PTEOS-derived films reported previously. Photobleaching of the luminescent complex in fluorinated and non-fluorinated matrices was also investigated. It was established that photobleaching was reduced but not eliminated in fluorinated films. All films produced in this study exhibit very good reproducibility, reversibility, enhanced sensitivity, humidity-insensitivity and long-term stability.
Novel sol-gel derived films for luminescence-based oxygen and pH sensing
2000
A range of both sol-gel and polymer derived sensor films have been developed for optical oxygen and pH sensing. Oxygen sensing is based on the luminescence quenching of the ruthenium complex (Ru(II)-tris( 4,7-diphenyl-1,10-phenanthroline))dichloride, ((Ru(dpp)3) 2+ ), which is entrapped in the sol-gel matrix. The oxygen-dependent luminescence is detected using the principle of phase fluorometry, which facilitates indirect monitoring of the
Materials Chemistry and Physics, 2009
Photophysical characteristics and emission based response of tris(2,2 -bipyridyl)ruthenium(II)chloride (Ru(bipy) 3 2+ ) to gaseous oxygen was investigated in ionic liquid modified sol-gel matrix. The ionic liquid; 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF 4 ) was used for the first time in acid-catalyzed tetraethyl orthosilicate (TEOS) based sol-gel matrix. Effects of the ionic liquid to the oxygen sensitivity and to surface characteristics were examined. EMIMBF 4 doped sol-gel slides exhibited enhanced O 2 sensitivity, larger Stern-Volmer constants, linear Stern-Volmer plots with respect to classical acid catalyzed sol-gel monoliths and completely crack-free surfaces. The utilization of EMIMBF 4 in sol-gel matrix also caused a red shift of 23 nm in the emission wavelength and an enhanced Stoke's shift value of (Ru(bipy) 3 2+ ) with respect to ionic liquid free sol-gel composites. The response and regeneration times were 5 and 10 s after exposure to 100% O 2 and 100% N 2 , respectively. The offered composite is only available for gas phase measurements.
2014 IEEE 10th International Colloquium on Signal Processing and its Applications, 2014
The fabrication and characterization of a fiber optic dissolved oxygen sensor based on the dynamic quenching of fluorescence from a ruthenium complex in gas and aqueous phase is presented. The unclad portion of the multimode optical fiber is coated with an oxygen sensitive ruthenium complex, which is immobilized by the sol-gel route. The intensity of the fluorescence emission has been found to decrease as the oxygen content increases. The dynamic range and the temporal response of the sensor are investigated for three different environment, gas, deionized water and sea water. The performance of the device is evaluated in terms of the results obtained during actual measurements.