Towards better understanding of C₆₀organosols

Abstract

It is of common knowledge that fullerenes form colloids in polar solvents. However, the coagulation via electrolytes and the origin of the negative charge of species are still unexplored. Using a 'radical scavenger' and electrospray ionization spectroscopy (ESI), we proved the formation of ion-radical C 60 À and its (probable) transformation into C 60 2À or (C 60 ) 2 2À.

Behavior of fullerene C70 in binary organic solvent mixtures as studied using UV-Vis spectra and dynamic light scattering

“…* The coagulation of such aggregates by electrolytes [29] additionally confirms their typically colloidal nature.…”

“…In a benzeneacetonitrile mixed solvent, the absorption band with max  = 335 nm at 50 % benzene is close to that in pure benzene (only the intensity drops by ca. 20 %), while the colloidal species with the size of 100-200 nm are registered via DLS; the data refer to C 60 concentration of 4×10 -5 M [29]. The data obtained for C 60 in the toluene-methanol system are of the same type [20].…”

The role of functionalization on the colloidal stability of aqueous fullerene C60 dispersions prepared with fullerides

“…The formation of metastable dispersions (1c, 2c) in organic media that are stable for weeks after exposition of fulleride solutions to air has not been reported in the literature to the best of our knowledge, although fullerenes are known to produce dispersions in polar solvents. [3,[38][39][40] This interpretation can be corroborated by UV-Vis-NIR spectra of 1c and 2c, as in both cases the characteristic absorption bands between 700 and 1300 nm of the respective anions vanish and the peaks below 400 nm characteristic of neutral C 60 broaden and increase (see Figure 2A and 2B).…”

“…Due to the low degree of functionalization and to their non-re-dispersibility after water addition (see Figure 4), dispersions 1d are lyophobic and the colloidal stability of those is provided by electrostatic repulsion. [19,[42][43][44][45] So, these dispersions can be considered as model to apply DLVO theory for carbon-based systems, [30] as has been done for fullerene dispersions made by other routes. [3,19,[44][45][46] Figure 5A presents a graphic of total interaction energy (U T ) as a function of distance for two identical spherical particles calculated based on DLVO theory, [47,48] considering the experimental radius (half of the diameters shown in Table S1) and zeta potentials for 1d dispersions, an approximate value for Hamaker constant (1 x 10 -19 J) from literature, [3] and 1:1 electrolyte (1 .…”

Liquid Systems with Fullerenes in Organic Solvents and Aqueous Media

“…The second half of the 1990s was devoted to the research of the properties of liquid systems with fullerenes. The aggregation processes and their dependence on the fullerene concentration [25][26][27][28][29] and the polarity of solvent mixtures [30][31][32][33][34][35][36] were intensively studied at that time. In particular, the origins of solvatochromic effects in the mixtures of solvents with fullerenes were determined [37,38], and the method of solvent exchange was invented [17,39].…”