Reactivity of fullerenes with chemically generated singlet oxygen

Influence of Oxygen-Containing Functional Groups on the Environmental Properties, Transformations, and Toxicity of Carbon Nanotubes

“…Photochemical transformations play a major role in regulating the surface properties of CNMs. For example, n-C 60 can be irradiated with UVC light or natural sunlight to form surface oxidized, hydrophilic C 60 derivatives with increased solubility in water as a result of new oxygen-containing surface functional groups (e.g., epoxide, ether, and hydroxyl). − The indirect photolysis mechanism driving these processes has been proposed to to rely on the formation of the excited triplet state of C 60 ( 3 C 60 ) through photoexcitation and conversion from the singlet state ( 1 C 60 ); the 3 C 60 then reacts with 1 O 2 species to form oxidized C 60 species. , Highly oxidized n-C 60 materials, modeled using fullerenol, are then susceptible to degradation and partial mineralization as a result of direct photolysis. , Similarly, GO materials are also known to partially mineralize under direct photolysis by both UVC and solar irradiation. , When exposed to sunlight, GO undergoes a rapid (<10 h) reaction to form smaller fragments of rGO materials, CO 2 , and low molecular weight photoproducts, in a process that has been hypothesized to be driven by electron–hole pair reactions . Continued irradiation up to the equivalent of two months of natural sunlight exposure results in slower transformation and further production of both oxidized (i.e., CO 2 ) and reduced (i.e., rGO fragments) product species, with the relative proportion of CO 2 vs rGO fragments depending on the presence or absence of dissolved O 2 in solution .…”

C60 degrades to C120O

“…C 60 O, which has been produced by oxidation of [60]fullerene under a variety of conditions viz. using photosensitizers, 10 chemically generated singlet oxygen, 11 dimethyldioxirane, 12 iodosobenzene/metal catalysts, 13 methyltrioxorhenium-hydrogen peroxide, 14 ozone, 15 3-chloroperbenzoic acid, 16 and electrochemistry. 17 It is widely assumed that C 60 undergoes oxidation to C 60 O on exposure to air, but we believe this has never been demonstrated.…”

The role of singlet oxygen in the photochemical formation of C60O

“…7 Juha et al showed some time ago that C 60 in fullerene-solvent clathrate microcrystallites was unreactive to a stream of chemically generated 1 O 2 . 10 The question then remains as to the role played by 1 O 2 in the photochemical formation of 1. Could an electronically excited state of C 60 lead to C 60 O by reaction with 1 O 2 ?…”