Simple Synthetic Method Toward Solid Supported C₆₀ Visible Light-Activated Photocatalysts

Solid supported fullerene materials are prepared in aims of creating a fullerene-based photocatalyst that is capable of producing ¹O₂ in the aqueous phase. Past studies of using fullerene as a photocatalyst in water have exclusively focused on using water soluble fullerene derivatives and employed sophisticated chemistry to create immobilized fullerene materials. The method presented herein is much less synthetically complex and utilizes pristine fullerene, providing a drastically simpler route to supported fullerene materials and furthering their potential for use in environmental applications. Covalent immobilization was achieved through the nucleophilic addition of a terminal amine (located on a solid support) across a [6,6] fullerene double bond, resulting in attachment directly to C₆₀’s cage. Immobilization allowed supported fullerene moieties to produce ¹O₂ in water under various illumination conditions and inactivate MS2 bacteriophages. In a water with natural organic matter, supported fullerene materials produced ¹O₂ under visible light irradiation without exhibiting significant loss of photocatalytic activity after successive cycling

Differential Photoactivity of Aqueous [C₆₀] and [C₇₀] Fullerene Aggregates

Many past studies have focused on the aqueous photochemical properties of colloidal suspensions of C₆₀ and various [C₆₀] fullerene derivatives, yet few have investigated the photochemistry of other larger cage fullerene species (e.g., C₇₀, C₇₄, C₈₄, etc.) in water. This is a critical knowledge gap because these larger fullerenes may exhibit different properties compared to C₆₀, including increased visible light absorption, altered energy level structures, and variable cage geometries, which may greatly affect aggregate properties and resulting aqueous photoactivity. Herein, we take the first steps toward a detailed investigation of the aqueous photochemistry of larger cage fullerene species, by focusing on [C₇₀] fullerene. We find that aqueous suspensions of C₆₀ and C₇₀, nC₆₀ and nC₇₀, respectively, exhibit many similar physicochemical properties, yet nC₇₀ appears to be significantly more photoactive than nC₆₀. Studies are conducted to elucidate the mechanism behind nC₇₀’s superior ¹O₂ generation, including the measurement of ¹O₂ production as a function of incident excitation wavelength, analysis of X-ray diffraction data to determine crystal packing arrangements, and the excited state dynamics of aggregate fullerene species via transient absorption spectroscopy

Dual-Functionality Fullerene and Silver Nanoparticle Antimicrobial Composites via Block Copolymer Templates

We present the facile prepartion of C₇₀ and Ag nanoparticle (NP) loaded block copolymer (BCP) thin films, with C₇₀ and Ag NPs working in tandem to provide virucidal and bactericidal activities, respectively. Polystyrene-<i>block</i>-poly-4-vinylpyridine (PS-P4VP) was used as a template, allowing C₇₀ integration into PS domains and in situ formation of Ag NPs in P4VP domains, while providing control of the nanoscale spatial distribution of functionality as a function of BCP molecular weight (MW). C₇₀ loaded PS-P4VP films were found to generate significant amounts of ¹O₂ under visible light illumination with no apparent dependence on BCP MW. An analogous C₇₀ loaded PS homopolymer film produced notably less ¹O₂, highlighting a possible critical role of morphology on C₇₀ photoactivity. The antimicrobial activity of Ag NP and C₇₀ loaded composites against the model PR772 bacteriophage and Escherichia coli was assessed, finding synergistic inactivation afforded by the dual functionality. BCPs were demonstrated as versatile platforms for the preparation of multifunctional antimicrobial coatings toward combating diverse microbial communities

Improving the Visible Light Photoactivity of Supported Fullerene Photocatalysts through the Use of [C₇₀] Fullerene

We herein present the first instance of employing [C₇₀] fullerene for photocatalytic ¹O₂ production in water, through covalent immobilization onto a mesoporous silica support via nucelophilic amine addition directly to fullerene’s cage. This attachment approach prevents the aggregation of individual fullerene molecules in water, thus allowing fullerene to retain its photoactivity, yet is much less complex than other techniques commonly pursued to create such supported-fullerene materials, which typically rely on water-soluble fullerene derivatives and elaborate immobilization methods. The solid-supported C₇₀ material exhibits significantly improved aqueous visible-light photoactivity compared to previous C₆₀- and C₆₀-derivative-based supported fullerene materials. Further, this material rapidly inactivates MS2 bacteriophage under sunlight illumination, oxidizes various organic contaminants, and does not appear to be significantly fouled by natural organic matter (NOM), highlighting the potential of these materials in real-world applications. Collectively, the ease of preparation and significantly enhanced visible-light photoactivity of these materials advance fullerene-based technologies for water treatment

Functionalized Fullerenes in Water: A Closer Look

The excellent photophysical properties of C₆₀ fullerenes have spurred much research on their application to aqueous systems for biological and environmental applications. Spontaneous aggregation of C₆₀ in water and the consequent diminution of photoactivity present a significant challenge to aqueous applications. The mechanisms driving the reduction of photoactivity in fullerene aggregates and the effects of functionalization on these processes, however, are not well understood. Here, we take a closer look at the molecular phenomena of functionalized fullerene interactions in water utilizing simulation and experimental tools. Molecular dynamic simulations were performed to investigate time-evolved molecular interactions in systems containing fullerenes with water, oxygen, and/or neighboring fullerene molecules, complimented by physical and chemical characterizations of the fullerenes pre- and postaggregation. Aggregates with widely different photoactivities exhibit similar fullerene–water interactions as well as surface and aggregation characteristics. Photoactive fullerene aggregates had weaker fullerene–fullerene and fullerene–O₂ interactions, suggesting the importance of molecular interactions in the sensitization route