Sn. Guha et Jp. Mittal, PULSE-RADIOLYSIS STUDY OF ONE-ELECTRON REDUCTION OF SAFRANINE-T, Journal of the Chemical Society. Faraday transactions, 93(20), 1997, pp. 3647-3652
Citations number
26
Categorie Soggetti
Chemistry Physical","Physics, Atomic, Molecular & Chemical
The one-electron reduction of safranine T by hydrated electrons and va
rious reducing organic radicals in aqueous solution has been studied b
y the technique of nanosecond pulse radiolysis. The absorption spectru
m of the transient semireduced safranine formed in these reactions exh
ibited lambda(max) at 400 and 650 nm with molar absorption coefficient
values of 6.88 x 10(3) and 9.9 x 10(3) dm(3) mol(-1) cm(-1) respectiv
ely and decayed obeying a second-order rate law with a bimolecular rat
e constant of 0.97 x 10(9) dm(3) mol(-1) s(-1) at neutral pH. It has t
wo pK(a) values of 3.0 and 8.5. The rate constants for the formation o
f semireduced safranine species by the reactions of most of the reduci
ng radicals with the dye were very high and nearly diffusion controlle
d. The one-electron reduction potential of safranine T was estimated t
o be -0.35 +/- 0.02 V as. NHE at pH 5. Reaction of H atoms with SF+ at
acidic pH was also studied. The results obtained have been discussed
with respect to the possibilities of different modes of H-atom reactio
ns with safranine T.