ELECTRON-SPIN-RESONANCE AND ELECTRON-SPIN ECHO MODULATION STUDIES ON PHOTOINDUCED CHARGE SEPARATION FROM N-ALKYLPHENOTHIAZINES IN SODIUM DODECYL-SULFATE MICELLES - EFFECT OF ALPHA-CYCLODEXTRIN AND BETA-CYCLODEXTRIN ADDITION

Photoinduced electron transfer from N-alkylphenothiazines (PCn, n = 3, 9, 12, 16) to D2O at a micellar interface was monitored versus the al kyl chain length of PCn and versus cyclodextrin (CD) addition into the micelle by determining the photoproduced radical yield by electron sp in resonance. The photoyield of PCn in sodium dodecyl sulfate micelles monotonically decreases with increasing concentration of alpha-CD. Th is results from an increased electron transfer distance between the ph enothiazine moiety and interface D2O by replacing some interface D2O w ith alpha-CD. Addition of beta-CD shows a different trend for the phot oyield. The photoyield increases with increasing concentration of beta -CD up to 10 mM and thereafter monotonically decreases. The increased photoyields up to 10 mM beta-CD result from a decreased interaction di stance between the phenothiazine moeity and D2O at the micellar interf ace by intercalation of beta-CD between the headgroups of the surfacta nt molecules. The decrease of photoyield above 10 mM beta-CD results f rom an initial increased interaction distance between the phenothiazin e moiety and interface water by replacing some D2O at the micellar int erface to 15 mM beta-CD and thereafter disrupting the micellar structu re by the high concentration of beta-CD.