Optimization of the solvent-exchange process for high-yield synthesis of aqueous fullerene dispersions

Abstract

The ultrasound-assisted solvent-exchange technique for aqueous fullerene dispersions (AFD) of C 60 (10 −4 -10 −6 M) have been improved for high-yield synthesis, thereby achieving AFDs with total recovery over 90 %. Using ICP-AES, HPLC-UV, HGC-MS, the elemental and residual organic compounds have been estimated as not exceeding 3 ppm. The possible structure of fullerene clusters in AFD was assumed as {n[C 60 ]mC 6 H 5 COO − (m − x)Na + }xNa + .

Green and rapid preparation of long-term stable aqueous dispersions of fullerenes and endohedral fullerenes: The pros and cons of an ultrasonic probe

“…The red shift in fullerene absorption spectra is still under discussion and requires a separate study. Still, overall shapes of absorption spectra for C 60 (direct and solvent-exchange sonication procedures) coincide with the previous studies [12] , [13] , [43] , [44] . In the case of a solvent-exchange procedure for C 70 , the spectrum is also very close to the previous data [43] .…”

“…For all dispersions, the ionic strength was low, 0.005 M. Zeta-potential values ( Table 1 ) characterize produced AFDs for all test fullerenes as moderately stable [58] and are in good accordance with the data for previously obtained unmodified fullerene nanoparticles [43] , [44] , [45] , [59] . For some samples of AFD C 60 , the stability was also checked for ionic strengths of up to 0.7 M, and the high stability of these suspensions was shown for strengths of <0.05 M [55] .…”

“…The optimum fullerene concentrations, ratio of the aqueous and organic phase with dissolved fullerene, and the time of ultrasonic treatment have already been determined for C 60 , C 70 [43] , [44] and Y@C 82 [45] . In this work, we projected our previously obtained data on the ultrasound-bath-assisted solvent-exchange process [43] , [44] , [45] , [46] onto an immersed ultrasound probe. On the other hand, an ultrasound probe was previously used for the preparation of fullerene derivatives only [25] , [47] .…”

Non-Functionalized Fullerenes and Endofullerenes in Aqueous Dispersions as Superoxide Scavengers

“…Another explanation for differences in antioxidant activity of fullerenes may be the sorption of benzoic acid on the cluster surface at the process of solvent replacement. Toluene is dispersed in this process, and due to the oxidizing atmosphere, high ultrasound power, and water sonolysis [49] with the formation of the OH• radical, toluene is oxidized to benzoic acid [50]. Benzoic acid itself has a pronounced antimicrobial effect [51], and its hydroxylated derivatives (2-hydroxybenzoic acid, etc.,) have an antioxidant effect beyond the phenol-like structure [52].…”

The use of nanocluster polyoxometalates in the bioactive substance delivery systems

“…This aspect makes fullerenes promising candidates as means of targeted drug delivery. However, fullerenes are hydrophobic, which limits the possibilities of their direct use in biomedicine [193] It is possible to obtain their aqueous dispersions [194][195][196][197][198][199][200] and associates with organic compounds [200][201][202][203][204][205]. One of the ways of modifying the surface of fullerenes provides hydroxylated derivatives such as fullerenols [195,200,205,206,208].…”