ELECTRON-TRANSFER STUDIES IN C-78 (C-2-NU'), C-76 (D-2), C-70 (D-5H),AND C-60 (I-H) SURFACTANT AQUEOUS-SOLUTIONS

C-60 (I-h) and several higher fullerenes, namely, C-70 (D-5h), C-76 (D -2), and C-78 (C-2v'), have been solubilized via capping with suitable surfactants. Excited states and reduced states of these surfactant sy stems were probed by photolytic and radiolytic techniques. mash photol ytic irradiation at 355 nm of surfactant solutions of C-60, C-70, C-76 , and C-78 revealed the rapid grow-in of transient (S-1 --> *S-n) abs orptions with lambda(max) at 920, 660, 650, and 890 nm, respectively. The associated intersystem crossing rates to the energetically lower l ying excited triplet states are typically on the order of 9.0 x 10(8) s(-1) Reductive quenching of the excited triplet states by diazabicycl ooctane (DABCO) occurs with (0.8-7.4) x 10(7) M-1 s(-1) and yields the fullerene pi-radical anions. Direct reduction of surfactant capped fu llerene monomers have been studied by means of time-resolved pulse rad iolysis with measurements being conducted in the near-IR region. Radio lytic reduction of (C-76)(surfactant) and (C-78)(surfactant) resulted in the formation of characteristic pi-radical anion bands positioned a t 920 and 980 nm, respectively. Rate constants have been measured for the reduction of these fullerene-surfactant systems with hydrated elec trons (k(et) = (2.6-3.9) x 10(10) M-1 s(-1)) and (CH3)(2) . C(OH) radi cals (k(et) = (3.0-7.2) x 10(8) M-1 s(-1)).