On the photoreduction of crystal violet, phenosafranine and methylene blue by benzophenone

✍ Scribed by S. Jockusch; H.J. Timpe; Ch.-H. Fischer; W. Schnabel

• Publisher: Elsevier Science
• Year: 1992
• Tongue: English
• Weight: 658 KB
• Volume: 63
• Category: Article
• ISSN: 1010-6030
• DOI: 10.1016/1010-6030(92)85139-l

✦ Synopsis

Benzophenone triplets (3BP*) react very effectively with the cations of crystal violet (CV+), methylene blue (MB*) and phenosafranine (PS') in argon-saturated acetonitrile solution at 23 "C: k, values (in M-' s-l) are (3 rt 1) x 10" (CV+), (7 f 1) X 1CP (MB+) and (5 * 1) x 10' (PS+). The results suggest that electron transfer occurs in the system 3BP*-CV', whereas triplet energy transfer is the dominant reaction route in the other two cases. Substituted methyl radicals generated by the reaction of 3BP* with several amines (triethanol amine, triethyl amine, dimethyl and diethyl aniline) are effectively oxidized by the three dye cations. Electron transfer rate constants k, ranging from 0.6 X lOlo to 3 X 10" M-' s-l were determined. The dye cations are less reactive towards ketyl radicals, e.g. k,[(Ph),C(OH) f CV*] = 2 X 10' M-l s-l and k,[(CH&COH + CV*] = 1.3 x 10' M-l s-l.