Facile Synthesis of Highly Water-Soluble Fullerenes More Than Half-Covered by Hydroxyl Groups

Abstract

Using a novel hydrogen peroxide heating method, we synthesized milky white, water-soluble polyhydroxylated fullerenes (fullerenols) with 36-40 hydroxyl groups (estimated average) along with 8-9 secondary bound water molecules. The fullerenols exhibited high water solubility up to 58.9 mg/mL in a neutral (pH = 7) condition. Dynamic light scattering analysis showed a high dispersion property, to give a narrow particle size distribution within 0.7-2.0 nm.

Basic hydrolysis of fullerene-based esters: a tiny step away from nucleophilic addition to fullerene

“…The research work related to fullerenols embraces wide spectrum of areas, e.g., studies of their electrolytic properties, 11 physicochemical characterization of their properties in water 12 and use in catalytic processes, 13 studies related to their application in drug delivery 14 and their biological activity. 15 Due to the popularity of fullerenols there still exists a need for improving the synthesis 16 and analytical methods for establishing their characterization. 17 During our recent attempts to further optimize hydrolysis of ethyl ester of T h -FHMA we have observed that under certain conditions a nucleophilic addition of -OH groups to fullerene C 60 cage takes place as a side reaction, leading to the formation of some kind of a hybrid with features of T h -symmetric FHMA and fullerenol (Scheme 1).…”

Water-Soluble Single-Nano Carbon Particles: Fullerenol and Its Derivatives

“…The narrow particle-size distributions around 1-2 nm in terms of the number of C 60 (OH) 36 and C 60 (OH) 44 molecules are essentially the same, indicating the highly dispersed nature of the fullerenols at a molecular level (Figure 3) (Kokubo et al, 2008;Kokubo et al, 2011). The average particle size of C 60 (OH) 44 was determined to be 1.46 ± 0.38 nm (N = 8).…”

“…Thus, we have found a new and facile approach for synthesizing high-degree fullerenols that have high water solubility without using any Na salts (Kokubo et al, 2008). The reddish brown suspension of fullerenol C 60 (OH) 12 in 30% aqueous H 2 O 2 was stirred vigorously at 60 °C under air until it turned to a transparent yellow solution, which occurred within 2-4 days (Scheme 2a).…”

“…However, these later fullerenols may be contaminated with Na salt because of the reagents used in synthesis, resulting in compositions with the formula Na + n [C 60 Ox(OH) y ] n-and exhibiting high water solubility in spite of their small number of hydroxyl groups (Husebo et al, 2004). In contrast, the high-degree hydroxylated fullerenols C 60 (OH) 36 and C 60 (OH) 44 , which are synthesized without using any Na salt, are completely water soluble by as much as 17 and 65 mg/mL, respectively (Kokubo et al, 2008;Kokubo et al, 2010). Particle size analysis revealed that the high-degree fullerenols exhibited high dispersion properties at a molecular level (ca.…”

Physical Properties of Organic Fullerene Cocrystals

“…Concerning the latter, while pristine C60 is not water soluble, functionalization with polar groups leads to derivatives with higher water affinity (Wang et al, 2005;Kokubo et al, 2008), which in some cases promotes the formation of hydrates from water solutions (Zachariah et al, 2015).…”