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

Abstract

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.

Spectroscopic and kinetic investigation of the interaction between crystal violet and sodium dodecylsulfate

“…2 is lower than the one observed by conductivity, viscosity and light-scattering measurements [35]. Lowering the cmc values in dye-surfactant systems has also been observed in the past by Mukerjee and Mysels [12b,36].…”

Redox Phenomena during Adsorption of Aniline on Fe‐ and Zn‐bound SDS Micelles

“…The same effect can be observed with opposite micelle polarity, with anionic oxidants like chromate associating to cationic micelles to oxidize compounds like D-glucose [2]. Redox reactions involving micelle-bound species like phenosafranine (PS) benefits also from this concentration effect of the charged species PS + upon SDS micelles [3], and in this case, micelle-binding of the reactants also alters the mechanism of the redox process, favoring the stability of the transient state.…”

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

“…In a pulse radiolysis study Mittal et al 44 reported ε R = 12 600 M −1 cm −1 at 410 nm and 11 300 M −1 cm −1 at 650 nm. Using the GSD method a lower limit of 7500 M −1 cm −1 and 8200 M −1 cm −1 at 650 and 410 nm, respectively, was obtained.…”

“…40 The oxidation potential of indole derivatives is 1.24 V for indole and tryptophan and 1.07 V vs. SCE for 3-methyl indole. 44 Using the triplet energy of the dye, 1.77 eV, 42,43 the reduction potential vs. SCE for the triplet state of the dye may be estimated as −1.20 V in water. 44 Using the triplet energy of the dye, 1.77 eV, 42,43 the reduction potential vs. SCE for the triplet state of the dye may be estimated as −1.20 V in water.…”

“…In the presence of the indoles the long time transient absorption spectrum differs from that in the absence of the quenchers. 44 However, the formation of the semireduced form of the dye does not follow simple kinetics. This new species can be attributed to the semireduced dye.…”