The Experts below are selected from a list of 288 Experts worldwide ranked by ideXlab platform
Hiromasa Nishikiori - One of the best experts on this subject based on the ideXlab platform.
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observation of photoinduced proton transfer between the titania surface and Dye molecule
Journal of Physical Chemistry C, 2020Co-Authors: Hiromasa Nishikiori, Hayato Kondo, Yosuke Kageshima, Nasrin Hooshmand, Sajanlal R Panikkanvalappil, David A Valverdechavez, Carlos Silva, Mostafa A Elsayed, Katsuya TeshimaAbstract:The photocatalyst titania film surface acquires a high hydrophilicity after it is exposed to UV light, which is induced by changes in the densities of the surface hydroxyl groups and charge. A Xanthene Dye, fluorescein, was deposited from a solution onto a titania film after UV irradiation in order to probe the titania surface change. The change in the surface acidity was confirmed by the ratio of the dianion to monoanion of fluorescein by Raman spectroscopy. The ratio increased by the UV irradiation, indicating that the surface became more basic. Transient absorption spectroscopy revealed the transformation from the monoanion to the dianion via the excited states, i.e., photoinduced proton transfer from the fluorescein to the titania surface. The UV irradiation increases the basic hydroxyl groups on the titania surface, which accepts protons from the water molecules or proton donors on the surface and has a positive charge.
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observation of photoinduced proton transfer between the titania surface and Dye molecule
The Journal of Physical Chemistry, 2020Co-Authors: Hiromasa Nishikiori, Hayato Kondo, Yosuke Kageshima, Nasrin Hooshmand, Sajanlal R Panikkanvalappil, David A Valverdechavez, Carlos Silva, Mostafa A Elsayed, Katsuya TeshimaAbstract:The photocatalyst titania film surface acquires a high hydrophilicity after it is exposed to UV light, which is induced by changes in the densities of the surface hydroxyl groups and charge. A Xanthene Dye, fluorescein, was deposited from a solution onto a titania film after UV irradiation in order to probe the titania surface change. The change in the surface acidity was confirmed by the ratio of dianion to monoanion of fluorescein by Raman spectroscopy. The ratio increased by UV irradiation, indicating that the surface became more basic. Transient absorption spectroscopy revealed the transformation from the monoanion to dianion via the excited states, that is, photoinduced proton transfer from fluorescein to the titania surface. The UV irradiation increases the basic hydroxyl groups on the titania surface, which accepts protons from the water molecules or proton donors on the surface and has a positive charge.
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Influence of Steam Treatment on Dye−Titania Complex Formation and Photoelectric Conversion Property of Dye-Doped Titania Gel
The Journal of Physical Chemistry C, 2011Co-Authors: Hiromasa Nishikiori, Rudi Agus Setiawan, Tsuneo Fujii, Yohei Uesugi, Shohei Takami, Wei Qian, Mostafa A. El-sayedAbstract:Xanthene Dye molecules form a chelate complex with the titanium species on the titania surface in Dye−titania systems. The complex formation causes a fast electron injection into the titania conduc...
Erjian Wang - One of the best experts on this subject based on the ideXlab platform.
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a water soluble supramolecular structured photosensitive initiation system me β cd complex of Xanthene Dye aryliodonium salt
Polymer, 2009Co-Authors: Erjian WangAbstract:Abstract A water-soluble supramolecular structured photosensitive initiator (SSPI) was developed by the supramolecular self-assembling between the photosensitizer (Xanthene Dye) and the initiator (Complex A). The structure of SSPI was characterized by static and dynamic fluorescence quenching method. The photolysis properties of SSPI in the film were evaluated. The photopolymerization of AM and bis-AM in the film using the SSPI as the photoinitiator was also carried out. The results indicated that the SSPI formation played an important role in the photolysis and photopolymerization process. The SSPI was an efficient water-soluble photosensitive initiator.
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a water soluble two photon photopolymerization initiation system methylated β cyclodextrin complex of Xanthene Dye aryliodonium salt
Journal of Photochemistry and Photobiology A-chemistry, 2009Co-Authors: Erjian WangAbstract:Abstract An effective two-photon photopolymerization in an aqueous environment was done using a new water-soluble two-photon photopolymerization (TPP) initiation system. This system comprised a photosensitizer Dye and the photoinitiator 4,4′-dimethyl diphenyliodonium hexafluorophosphate (DMDPI) encapsulated by methylated-β-cyclodextrin (Me-β-CD). Photochemical properties of the complex were studied in film. We proved that the complex can be used as an effective TPP photoinitiator for two-photon photopolymerization in an aqueous system. Three-dimensional microstructure was successfully fabricated by TPP.
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multi Dye photosensitization system of Xanthene iodonium salts
Journal of Photopolymer Science and Technology, 1994Co-Authors: Wenhui Zhou, Erjian WangAbstract:We have synthesised the serries of Xanthene Dye iodouium (XT On, including FL, FC, FI, EO, ER and RB) and studied their spectral properities and photochemical behavior. Under irradiation of visible light, the electron transfer reaction which occured between xanthenic moiety and oaium caused the photolysis of onium to generate active radical, simultaneousty, Xanthene Dye occured photobleaching reaction. The results of spectral kinetic studies indicate that their photobleaching rate is in the order of FL>FC>FI>EO>ER>RB. At the same time, we have also studied the role of energy transfer sensitization among different Xanthene Dyes, and depended on this method to speed up the photobleaching reaction. In photochemical reaction system of multi-Xanthene iodonium, the rate of electron transfer process is higher than the one of energy transfer process, so their photochemical reaction is equivalent to the one of each single component . On the basis of the result, different systems of multi-Xanthene onium can be used in the certain ranges of wave length, for their spectral response covers most region of visible light from 440nm to 600nm. Application of the multi-Dye photosensitization system can effectively improved the effecience of photopolymeization initiated radical.
Luis Crovetto - One of the best experts on this subject based on the ideXlab platform.
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A solvatofluorochromic silicon-substituted Xanthene Dye useful in bioimaging
Dyes and Pigments, 2019Co-Authors: Laura Espinar-barranco, Pilar Luque-navarro, Maja A. Strnad, Pilar Herrero-foncubierta, Luis Crovetto, Delia Miguel, María D. Girón, Angel Orte, Juan M. Cuerva, Rafael SaltoAbstract:Abstract In this work, we have performed an in-depth study of the photophysics and solvatofluorochromism of a red-emitting Si-Xanthene Dye, an analog of Tokyo Magenta (TM) historically developed by Egawa et al. (Chem. Commun. 2011, 47, 4162–4164). The results show a strong dependency of the emission properties of 2-Me-4-OMe-TM on the polarity of the solvent. For instance, the Dye exhibited an increase in its fluorescence lifetime with the decrease in solvent polarity. Therefore, in this work, this spectral behavior has been used as a new approach for determining the intracellular microenvironment polarity through the measurement of its fluorescence lifetime by Fluorescence Lifetime Imaging Microscopy (FLIM). Our experiments confirmed the ability of the Dye to detect changes in polarity between different intracellular compartments.
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design synthesis and photophysical studies of improved Xanthene Dye to detect acetate
2018Co-Authors: Jose M Paredes, Delia Miguel, Juan M. Cuerva, Sandra Resa, Maria Del Carmen Gonzalezgarcia, Yanira Diaztorres, Luis CrovettoAbstract:Abstract Development of biomarkers of analytes with interest in clinic is an important field of study. In this work, we synthesized and analyzed the new fluorescent acetate-biomarker, Iso-PG. The mechanism of detection is the acetate buffer mediated proton transfer reaction. The rate constants involved were obtained, and we measured the change in the fluorescence lifetime produced as a consequence of the presence of acetate in the medium. Finally, we checked its potential use as acetate biomarker in synthetic serum.
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photophysics of a live cell marker red silicon substituted Xanthene Dye
Journal of Physical Chemistry A, 2015Co-Authors: Luis Crovetto, Delia Miguel, Angel Orte, Juan M. Cuerva, Jose M Paredes, Sandra Resa, Javier Valverde, Fabio Castello, Eva M Talavera, Jose M AlvarezpezAbstract:Dyes with near-red emission are of great interest because of their undoubted advantages for use as probes in living cells. In-depth knowledge of their photophysics is essential for employment of such Dyes. In this article, the photophysical behavior of a new silicon-substituted Xanthene, 7-hydroxy-5,5-dimethyl-10-(o-tolyl)dibenzo[b,e]silin-3(5H)-one (2-Me TM), was explored by means absorption, steady-state, and time-resolved fluorescence. First, the near-neutral pH, ground-state acidity constant of the Dye, pKN-A, was determined by absorbance and steady-state fluorescence at very low buffer concentrations. Next, we determined whether the addition of phosphate buffer promoted the excited-state proton-transfer (ESPT) reaction among the neutral and anion form of 2-Me TM in aqueous solutions at near-neutral pH. For this analysis, both the steady-state fluorescence method and time-resolved emission spectroscopy (TRES) were employed. The TRES experiments demonstrated a remarkably favored conversion of the neutral form to the anion form. Then, the values of the excited-state rate constants were determined by global analysis of the fluorescence decay traces recorded as a function of pH, and buffer concentration. The revealed kinetic parameters were consistent with the TRES results, exhibiting a higher rate constant for deprotonation than for protonation, which implies an unusual low value of the excited-state acidity constant pK*N-A and therefore an enhanced photoacid behavior of the neutral form. Finally, we determined whether 2-Me TM could be used as a sensor inside live cells by measuring the intensity profile of the probe in different cellular compartments of HeLa 229 cells.
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Photophysics of a Live-Cell-Marker, Red Silicon-Substituted Xanthene Dye
2015Co-Authors: Luis Crovetto, Delia Miguel, Angel Orte, Juan M. Cuerva, Jose M Paredes, Sandra Resa, Javier Valverde, Fabio Castello, Eva M Talavera, Jose M. Alvarez-pezAbstract:Dyes with near-red emission are of great interest because of their undoubted advantages for use as probes in living cells. In-depth knowledge of their photophysics is essential for employment of such Dyes. In this article, the photophysical behavior of a new silicon-substituted Xanthene, 7-hydroxy-5,5-dimethyl-10-(o-tolyl)dibenzo[b,e]silin-3(5H)-one (2-Me TM), was explored by means absorption, steady-state, and time-resolved fluorescence. First, the near-neutral pH, ground-state acidity constant of the Dye, pKN‑A, was determined by absorbance and steady-state fluorescence at very low buffer concentrations. Next, we determined whether the addition of phosphate buffer promoted the excited-state proton-transfer (ESPT) reaction among the neutral and anion form of 2-Me TM in aqueous solutions at near-neutral pH. For this analysis, both the steady-state fluorescence method and time-resolved emission spectroscopy (TRES) were employed. The TRES experiments demonstrated a remarkably favored conversion of the neutral form to the anion form. Then, the values of the excited-state rate constants were determined by global analysis of the fluorescence decay traces recorded as a function of pH, and buffer concentration. The revealed kinetic parameters were consistent with the TRES results, exhibiting a higher rate constant for deprotonation than for protonation, which implies an unusual low value of the excited-state acidity constant pK*N‑A and therefore an enhanced photoacid behavior of the neutral form. Finally, we determined whether 2-Me TM could be used as a sensor inside live cells by measuring the intensity profile of the probe in different cellular compartments of HeLa 229 cells
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rational design of a new fluorescent on off Xanthene Dye for phosphate detection in live cells
Organic and Biomolecular Chemistry, 2014Co-Authors: Angela Martinezperagon, Delia Miguel, Angel Orte, Juan M. Cuerva, Jose M Alvarezpez, Antonio J Mota, Maria J Ruedasrama, Jose Justicia, Luis CrovettoAbstract:A new fluorescein derivative with ON/OFF features, 9-[1-(4-tert-butyl-2-methoxyphenyl)]-6-hydroxy-3H-xanthen-3-one (Granada Green, GG), was designed and synthesised. The new Dye has spectral characteristics similar to those of other xanthenic derivatives but shows a higher pKa value for the equilibrium between its neutral and anionic forms. In addition, GG undergoes the same phosphate-mediated excited state proton transfer (ESPT) reaction as other xanthenic derivatives, giving rise to fluorescence decay traces that are dependent on both the phosphate concentration and pH of the medium. The phosphate-mediated ESPT reaction was employed to detect changes in the phosphate concentrations in live, permeabilised MC3T3-E1 preosteoblasts at pH 7.35. Its high pKa value indicates that this new Dye is more sensitive as an intracellular phosphate sensor than other previously tested Dyes, as experimentally demonstrated by its ability to detect a wider range of phosphate concentrations in biomimetic media and by the increased ratio of the phosphate concentration/decay time.
Huiyu Zhang - One of the best experts on this subject based on the ideXlab platform.
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Interaction between triethanolamine and singlet or triplet excited state of Xanthene Dyes in aqueous solution.
Spectrochimica acta. Part A Molecular and biomolecular spectroscopy, 2017Co-Authors: Huiyu ZhangAbstract:Triethanolamine (TEOA) has been often used as a hole-scavenger in Dye-sensitized semiconductor photocatalytic systems. However, the femtosecond time-resolved kinetics of the interaction between a sensitized Dye and TEOA has not been reported in literatures. Herein, we selected four commonly used Xanthene Dyes, such as fluorescein, dibromofluorescein, eosin Y, and erythrosine B, and studied their ultrafast fluorescence quenching dynamics in the presence of TEOA in aqueous solution, respectively, by using both femtosecond transient absorption and time-resolved fluorescence measurements. We obtained the electron transfer rate from TEOA to each photoexcited Xanthene Dye in 2.0 M TEOA solution. We also obtained the intersystem crossing rate of each Xanthene Dye in aqueous solution with fluorescence quantum yield and lifetime measurements. Finally we found that TEOA mainly interacts with the singlet excited-state of fluorescein, dibromofluorescein, and eosin Y, and that TEOA can interact with both the singlet and triplet excited-states of erythrosine B in high concentration of TEOA aqueous solution.
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Time-Resolved Study on Xanthene Dye-Sensitized Carbon Nitride Photocatalytic Systems
ACS applied materials & interfaces, 2015Co-Authors: Huiyu ZhangAbstract:Dye sensitization is a promising strategy to extend the visible light absorption of carbon nitride (C3N4) and increase the photocatalytic hydrogen evolution efficiency of C3N4 under visible light irradiation. However, the interaction dynamics between C3N4 and a sensitized Dye has not been reported in the literature. Herein, we selected four commonly used Xanthene Dyes such as fluorescein, dibromofluorescein, eosin Y, and erythrosine B and prepared their corresponding Dye-sensitized-C3N4 composites. For the first time, we derived the electron transfer rate from the LUMO of each photoexcited Xanthene Dye to the conduction band of C3N4 using picoesecond time-resolved fluorescence measurements. We also obtained the reduction potentials of all selected Xanthene Dyes and C3N4 with cyclic voltammetry measurements. The cyclic voltammetry measurements gave a consistent result with the picosecond time-resolved fluorescence measurements. Besides, the possibility of the selected Xanthene Dye as an acceptor for the ho...
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Time-Resolved Study on Xanthene Dye-Sensitized Carbon Nitride Photocatalytic Systems
2015Co-Authors: Huiyu ZhangAbstract:Dye sensitization is a promising strategy to extend the visible light absorption of carbon nitride (C3N4) and increase the photocatalytic hydrogen evolution efficiency of C3N4 under visible light irradiation. However, the interaction dynamics between C3N4 and a sensitized Dye has not been reported in the literature. Herein, we selected four commonly used Xanthene Dyes such as fluorescein, dibromofluorescein, eosin Y, and erythrosine B and prepared their corresponding Dye-sensitized-C3N4 composites. For the first time, we derived the electron transfer rate from the LUMO of each photoexcited Xanthene Dye to the conduction band of C3N4 using picoesecond time-resolved fluorescence measurements. We also obtained the reduction potentials of all selected Xanthene Dyes and C3N4 with cyclic voltammetry measurements. The cyclic voltammetry measurements gave a consistent result with the picosecond time-resolved fluorescence measurements. Besides, the possibility of the selected Xanthene Dye as an acceptor for the hole of the photoexcited C3N4 was also discussed. We believe this study is significant for the researcher to understanding the fundamental aspects in the Xanthene Dye-sensitized-C3N4 photocatalytic systems
Delia Miguel - One of the best experts on this subject based on the ideXlab platform.
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A solvatofluorochromic silicon-substituted Xanthene Dye useful in bioimaging
Dyes and Pigments, 2019Co-Authors: Laura Espinar-barranco, Pilar Luque-navarro, Maja A. Strnad, Pilar Herrero-foncubierta, Luis Crovetto, Delia Miguel, María D. Girón, Angel Orte, Juan M. Cuerva, Rafael SaltoAbstract:Abstract In this work, we have performed an in-depth study of the photophysics and solvatofluorochromism of a red-emitting Si-Xanthene Dye, an analog of Tokyo Magenta (TM) historically developed by Egawa et al. (Chem. Commun. 2011, 47, 4162–4164). The results show a strong dependency of the emission properties of 2-Me-4-OMe-TM on the polarity of the solvent. For instance, the Dye exhibited an increase in its fluorescence lifetime with the decrease in solvent polarity. Therefore, in this work, this spectral behavior has been used as a new approach for determining the intracellular microenvironment polarity through the measurement of its fluorescence lifetime by Fluorescence Lifetime Imaging Microscopy (FLIM). Our experiments confirmed the ability of the Dye to detect changes in polarity between different intracellular compartments.
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design synthesis and photophysical studies of improved Xanthene Dye to detect acetate
2018Co-Authors: Jose M Paredes, Delia Miguel, Juan M. Cuerva, Sandra Resa, Maria Del Carmen Gonzalezgarcia, Yanira Diaztorres, Luis CrovettoAbstract:Abstract Development of biomarkers of analytes with interest in clinic is an important field of study. In this work, we synthesized and analyzed the new fluorescent acetate-biomarker, Iso-PG. The mechanism of detection is the acetate buffer mediated proton transfer reaction. The rate constants involved were obtained, and we measured the change in the fluorescence lifetime produced as a consequence of the presence of acetate in the medium. Finally, we checked its potential use as acetate biomarker in synthetic serum.
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photophysics of a live cell marker red silicon substituted Xanthene Dye
Journal of Physical Chemistry A, 2015Co-Authors: Luis Crovetto, Delia Miguel, Angel Orte, Juan M. Cuerva, Jose M Paredes, Sandra Resa, Javier Valverde, Fabio Castello, Eva M Talavera, Jose M AlvarezpezAbstract:Dyes with near-red emission are of great interest because of their undoubted advantages for use as probes in living cells. In-depth knowledge of their photophysics is essential for employment of such Dyes. In this article, the photophysical behavior of a new silicon-substituted Xanthene, 7-hydroxy-5,5-dimethyl-10-(o-tolyl)dibenzo[b,e]silin-3(5H)-one (2-Me TM), was explored by means absorption, steady-state, and time-resolved fluorescence. First, the near-neutral pH, ground-state acidity constant of the Dye, pKN-A, was determined by absorbance and steady-state fluorescence at very low buffer concentrations. Next, we determined whether the addition of phosphate buffer promoted the excited-state proton-transfer (ESPT) reaction among the neutral and anion form of 2-Me TM in aqueous solutions at near-neutral pH. For this analysis, both the steady-state fluorescence method and time-resolved emission spectroscopy (TRES) were employed. The TRES experiments demonstrated a remarkably favored conversion of the neutral form to the anion form. Then, the values of the excited-state rate constants were determined by global analysis of the fluorescence decay traces recorded as a function of pH, and buffer concentration. The revealed kinetic parameters were consistent with the TRES results, exhibiting a higher rate constant for deprotonation than for protonation, which implies an unusual low value of the excited-state acidity constant pK*N-A and therefore an enhanced photoacid behavior of the neutral form. Finally, we determined whether 2-Me TM could be used as a sensor inside live cells by measuring the intensity profile of the probe in different cellular compartments of HeLa 229 cells.
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Photophysics of a Live-Cell-Marker, Red Silicon-Substituted Xanthene Dye
2015Co-Authors: Luis Crovetto, Delia Miguel, Angel Orte, Juan M. Cuerva, Jose M Paredes, Sandra Resa, Javier Valverde, Fabio Castello, Eva M Talavera, Jose M. Alvarez-pezAbstract:Dyes with near-red emission are of great interest because of their undoubted advantages for use as probes in living cells. In-depth knowledge of their photophysics is essential for employment of such Dyes. In this article, the photophysical behavior of a new silicon-substituted Xanthene, 7-hydroxy-5,5-dimethyl-10-(o-tolyl)dibenzo[b,e]silin-3(5H)-one (2-Me TM), was explored by means absorption, steady-state, and time-resolved fluorescence. First, the near-neutral pH, ground-state acidity constant of the Dye, pKN‑A, was determined by absorbance and steady-state fluorescence at very low buffer concentrations. Next, we determined whether the addition of phosphate buffer promoted the excited-state proton-transfer (ESPT) reaction among the neutral and anion form of 2-Me TM in aqueous solutions at near-neutral pH. For this analysis, both the steady-state fluorescence method and time-resolved emission spectroscopy (TRES) were employed. The TRES experiments demonstrated a remarkably favored conversion of the neutral form to the anion form. Then, the values of the excited-state rate constants were determined by global analysis of the fluorescence decay traces recorded as a function of pH, and buffer concentration. The revealed kinetic parameters were consistent with the TRES results, exhibiting a higher rate constant for deprotonation than for protonation, which implies an unusual low value of the excited-state acidity constant pK*N‑A and therefore an enhanced photoacid behavior of the neutral form. Finally, we determined whether 2-Me TM could be used as a sensor inside live cells by measuring the intensity profile of the probe in different cellular compartments of HeLa 229 cells
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rational design of a new fluorescent on off Xanthene Dye for phosphate detection in live cells
Organic and Biomolecular Chemistry, 2014Co-Authors: Angela Martinezperagon, Delia Miguel, Angel Orte, Juan M. Cuerva, Jose M Alvarezpez, Antonio J Mota, Maria J Ruedasrama, Jose Justicia, Luis CrovettoAbstract:A new fluorescein derivative with ON/OFF features, 9-[1-(4-tert-butyl-2-methoxyphenyl)]-6-hydroxy-3H-xanthen-3-one (Granada Green, GG), was designed and synthesised. The new Dye has spectral characteristics similar to those of other xanthenic derivatives but shows a higher pKa value for the equilibrium between its neutral and anionic forms. In addition, GG undergoes the same phosphate-mediated excited state proton transfer (ESPT) reaction as other xanthenic derivatives, giving rise to fluorescence decay traces that are dependent on both the phosphate concentration and pH of the medium. The phosphate-mediated ESPT reaction was employed to detect changes in the phosphate concentrations in live, permeabilised MC3T3-E1 preosteoblasts at pH 7.35. Its high pKa value indicates that this new Dye is more sensitive as an intracellular phosphate sensor than other previously tested Dyes, as experimentally demonstrated by its ability to detect a wider range of phosphate concentrations in biomimetic media and by the increased ratio of the phosphate concentration/decay time.
