Photophysical and Electron Transfer Properties of C₆₀(C₆H₅)₅OH and C₆₀(C₆H₄F)₅OH: A Laser Flash Photolysis and Pulse Radiolysis Study

Abstract

Photophysical properties of the excited singlet and triplet states of pentaphenylfulleren-2-ol (C60(C6H5)5OH, PPF) and penta-4-fluorophenylfulleren-2-ol [C60(C6H4F)5OH, PFPF], two derivatives of buckminsterfullerene, C60, have been investigated in benzene and benzonitrile solutions using two complementary transient absorption techniques, namely, laser flash photolysis and pulse radiolysis. Singlet−singlet and triplet−triplet absorption spectra have been characterized. Quantum yields for formation of the triplet states by intersystem crossing from the singlet states, and also the intrinsic lifetimes of the singlet and triplet states, have been determined. In addition to the intrinsic decay of the triplet state, the evidences have been obtained for the contribution of the other two processes, namely, the self-quenching by the ground state and the T−T annihilation reaction, toward the decay of the triplet state, and the rate constants for these processes have been determined. The formation of charge transfer (CT) complexes with two aromatic amines, diphenylamine (DPA) and triphenylamine (TPA), in benzonitrile and the electron transfer reactions in the excited singlet and CT complexes have been studied.

Photochemical Properties and Activity of Water‐Soluble Polymer/C60 Nanohybrids for Photodynamic Therapy

“…Triplet state absorption spectra recorded under anaerobic conditions (squares in Figure 2) show one broad absorption peaking at 640–660 nm. This band corresponds to T 1 → T n transitions usually observed in C 60 adducts 43–46. Further confirmation that the transient state observed in Figure 2 corresponds to the triplet state is given by its quenching in the presence of oxygen.…”

Excited-State Dynamics and Photophysical Properties of para-Aminobenzophenone

“…Steady-state fluorescence spectra were recorded with this same setup by blocking the probe light, and the fluorescence yields were determined by comparing the areas under the fluorescence curves with that of a standard, pentaphenylfullerene-2-ol (PPF), under the same experimental conditions. The fluorescence quantum yield for PPF in benzene solution has been reported to be 0.7 × 10 -3 . Transient species surviving beyond 100 ns were studied by monitoring the optical absorption using the same picosecond Nd:YAG laser for excitation and a continuous-wave tungsten lamp, in combination with a Bausch & Lomb monochromator (350−800 nm) and a Hamamatsu R928 PMT, 500-MHz digital oscilloscope (Tektronix, TDS-540A) connected to a PC.…”

Thermally Stable Perfluoroalkylfullerenes with the Skew-Pentagonal-Pyramid Pattern: C60(C2F5)4O, C60(CF3)4O, and C60(CF3)6

“…The C s -C 60 X 6 skew-pentagonal-pyramid (SPP) addition pattern is exhibited by the regioisomer most commonly observed when each of six X addends forms a σ bond with one of six different cage C atoms. , Examples of compounds with this structure include C 60 Br 6 , , C 60 Cl 6 , , C 60 Me 6 , C 60 Me 5 Cl, C 60 Ar 5 Cl, C 60 Ar 5 H, , one isomer of C 60 Ph 5 (OH), − C 60 ( t -BuOO) 4 X(OH) (X = F, Cl, t -BuOO, OOH), and C 60 (OR) 5 Cl (R = Me, Et), some of which were among the first isolable exohedral derivatives of C 60 . , Two views of a fragment of the SPP C s -C 60 Br 6 structure 3,4 are shown in Figure S-1 (Supporting Information), and a generic C 60 X 6 SPP Schlegel diagram is shown in Figure . Five of the X substituents are positioned on a para 5 ( p 5 ) loop of five edge-sharing p -C 6 X 2 hexagons, and the sixth substituent is positioned ortho to one and meta to two of the first five.…”