Transient Photochemistry of Safranin-O

Baumgartner, Charles E.; Richtol, H. H.; Aikens, D. A.

doi:10.1111/j.1751-1097.1981.tb08954.x

Cited by 20 publications

(15 citation statements)

References 16 publications

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“…Similar studies were reported with other members (e.g. Safranine T and Safranine O) using flash photolysis technique 4–7. The semireduced safranine species cannot exclusively be produced by flash photolysis of the parent dye molecule without the presence of dye triplet and also the radicals derived from externally added reducing agents such as EDTA, ascorbic acid, etc 6.…”

Section: Introductionsupporting

confidence: 83%

“…Thus, for example, the phenazine dye, Safranine T (SF + ) has been considered to be a well‐known sensitizer and in order to explain the photopotential of a photogalvanic cell employing the SF + –EDTA system 1, the semireduced safranine radical was postulated as the electroactive species. Formation of semireduced species of phenazinium dyes has been demonstrated in flash photolysis experiments 4–7. Also, in the case of thiazine dyes the formation of the semireduced species was observed 8–12 in both flash photolysis and pulse radiolysis experiments.…”

Section: Introductionmentioning

confidence: 81%

“…Also, in the case of thiazine dyes the formation of the semireduced species was observed 8–12 in both flash photolysis and pulse radiolysis experiments. Generally in the photoreduction of dyes an intermediate semireduced radical is formed through the excited states of the dye in the presence of a suitable reducing agent 6. Chlorophyll‐sensitized reduction of safranine has been investigated in the past 3, in connection with the elucidation of the mechanism of photosynthesis in the plant.…”

Section: Introductionmentioning

confidence: 99%

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Kinetic and redox characteristics of semireduced species derived from phenosafranine in homogeneous aqueous and sodium dodecyl sulfate micellar media

Gawandi

Guha

Mohan

et al. 2001

Int J of Chemical Kinetics

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One-electron reduction of phenosafranine (PS + , 3,7-diamino-5-phenylphenazinium chloride), a phenazinium dye, has been studied in homogeneous aqueous and sodium dodecyl sulfate (SDS) micellar media, using the pulse radiolysis technique. The various reducing radicals employed for the study in homogeneous aqueous medium were e aq − , H · , CO 2 ·− , and isopropyl ketyl radicals (CH 3 ) 2 · COH. Semireduced species generated by these reactions have been characterized by their absorption spectra, decay kinetics, and pK a . The one-electron reduction potential of PS + was determined at pH 7 in homogeneous aqueous solution employing nitrobenzene (NB/NB ·− ) as the standard couple. One-electron reduction in SDS micellar medium and a detailed spectrophotometric investigation of the parent dye in this surfactant system was carried out in order to understand the dye-surfactant interactions in the micellar and premicellar media.

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Section: Introductionsupporting

confidence: 83%

Section: Introductionmentioning

confidence: 81%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Kinetic and redox characteristics of semireduced species derived from phenosafranine in homogeneous aqueous and sodium dodecyl sulfate micellar media

Gawandi

Guha

Mohan

et al. 2001

Int J of Chemical Kinetics

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“…2 and the pH dependence of the three maxima are presented in Fig. 36 In water at pH 7 the triplet state decays by a first order process with a lifetime in the range of 20-100 μs depending on the dye concentration. Under our experimental conditions in the quenching experiments, pH 7-8, the predominant species is the monoprotonated triplet.…”

Section: Photophysics Of the Dyementioning

confidence: 99%

“…11,12 SF + and PSH + were used as sensitizers in a large number of applications. 25,34,35 In a pioneering work, Baumgartner et al 36 have studied the triplet state properties of SH + as a function of pH in aqueous media using conventional flash photolysis. The electrochemistry of these dyes was investigated long ago by Clark and co-workers 23 and more recently the electrochromic properties of PSH + were reported.…”

Section: Introductionmentioning

confidence: 99%

Triplet state quenching of phenosafranine dye by indolic compounds studied by transient absorption spectroscopy

Broglia

Previtali

Bertolotti

2015

Photochem Photobiol Sci

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The interaction of the triplet state of the synthetic dye phenosafranine (3,7-diamino-5-phenylphenazinium chloride) with indolic compounds of biological relevance was investigated in water by means of laser flash photolysis. The rate constants for the triplet quenching were determined. The quenching process may be explained by an electron transfer from the indole to the dye in its triplet state. The rate constants present a typical dependence of an electron transfer process with the one-electron oxidation potential of the indole. Indole-3-acetic acid and its homologous indole propionic and indole butyric acids are the most effective quenchers with rate constants reaching the diffusion limit. Rate constants for indole itself, tryptophan and indole-3 carboxylic acid are one order of magnitude lower. The electron transfer nature of the quenching reaction is further confirmed by the detection of the semi-reduced form of the dye by its transient absorption. The absorption coefficients of the transient species were estimated, and the quantum yield of the charge separation process was determined. The efficiency of formation of radical species is between 60 and 90% of the triplets intercepted.

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Synthesis of poly(HEMA‐co‐AAm) hydrogels by visible‐light photopolymerization of aqueous solutions containing aspirin or ibuprofen: analysis of the initiation mechanism and the drug release

Gómez

Gallastegui

Spesia

et al. 2016

Polymers for Advanced Techs

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Recently, we reported the synthesis of hydrogels by visible‐light photopolymerization of 2‐hydroxyethylmethacrylate and acrylamide, employing safranine O as sensitizer, and a functionalized silsequioxane (SFMA) as co‐initiator/crosslinker. The influence of the ionic character of a drug on its release rate from the hydrogels was also reported. In the present study, we analyzed the photoinitiation mechanism, the synthesis of hydrogels in the presence of aspirin (ASA) or ibuprofen (Ibu), and their release from hydrogels synthesized with variable SFMA concentrations. Concerning the photoinitiation mechanism, we found that the main contribution was the electron transfer reaction between the excited triplet state of safranine and SFMA, followed by a fast proton transfer reaction from secondary amine groups. The generated nitrogen radicals initiated the copolymerization reaction. The photoreaction quantum yield was 0.031. Concerning the drug‐release study, we found that the release rate of both drugs increased by increasing pH from 7 to 10. This was ascribed to the increase in the partial ionization of the carboxylic acid groups, a fact that reduced the interactions with the secondary amine groups present in SFMA and increased the release rate. The effect was larger for ASA than for Ibu. Increasing the amount of SFMA increased both the crosslink density and the fraction of H‐bonds formed with the drugs. At pH 10, the increment in the crosslink density was dominant for the release of Ibu while the increase in fraction of H‐bonds determined the release rate of ASA. Cytotoxicity studies showed that these materials did not exhibit significant hemolytic activity. Copyright © 2016 John Wiley & Sons, Ltd.

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Transient Photochemistry of Safranin-O

Cited by 20 publications

References 16 publications

Kinetic and redox characteristics of semireduced species derived from phenosafranine in homogeneous aqueous and sodium dodecyl sulfate micellar media

Kinetic and redox characteristics of semireduced species derived from phenosafranine in homogeneous aqueous and sodium dodecyl sulfate micellar media

Triplet state quenching of phenosafranine dye by indolic compounds studied by transient absorption spectroscopy

Synthesis of poly(HEMA‐co‐AAm) hydrogels by visible‐light photopolymerization of aqueous solutions containing aspirin or ibuprofen: analysis of the initiation mechanism and the drug release

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