Towards better understanding of C organosols

• Published in: Physical chemistry chemical physics : PCCP 2016-01, Vol.18 (4), p.2517-2526
• Main Authors: Mchedlov-Petrossyan, Nikolay O, Kamneva, Nika N, Al-Shuuchi, Younis T. M, Marynin, Andriy I, Zozulia, Olexii S, Kryshtal, Alexander P, Klochkov, Vladimir K, Shekhovtsov, Sergey V
• Format: Article
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/c5cp06806a

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 &z.rad; − and its (probable) transformation into C 60 2− or (C 60 ) 2 2− . The coagulation of C 60 organosols by NaClO 4 and other perchlorates and nitrates in acetonitrile and its mixture with benzene obeys the Schulze-Hardy rule. At higher Ca(ClO 4 ) 2 and La(ClO 4 ) 3 concentrations, instead of coagulation, stable re-charged colloidal particles appeared, up to a zeta-potential of +(20-42) mV, as compared with −(33-35) mV of the initial organosols. The influence of both HClO 4 and CF 3 SO 3 H was similar. This phenomenon is attributed to poor solvation of inorganic cations in cationo- and protophobic acetonitrile, which was proven using [2.2.2] cryptand. Further increasing the concentration of Ca(ClO 4 ) 2 led again to coagulation, thus demonstrating a novel type of 'coagulation zones'. The C 60 colloidal species in acetonitrile are negatively charged owing to formation of anion-radicals. Electrolytes coagulate the organosol, and multi-charged cations cause the re-charging of the particles.