Dielectric and Sorption Responses of Hydrogen-Bonding Network of Amorphous C60(OH)12 and C60(OH)36

Abstract

Hydrophilic fullerene derivatives of C60(OH)12 (1) and C60(OH)36 (2) bearing different numbers of −OH groups formed amorphous solids of 1·x(H2O) (x = 5–10) and 2·x(H2O) (x = 15–22), respectively, according to the humidity. The thermally activated dynamic molecular motion of polar H2O was confirmed in the DSC and dielectric spectra. Three-dimensional O–H···O hydrogen-bonding networks in amorphous 1 and 2 produced extrinsic adsorption–desorption pores with a hydrophilic environment posed by −OH groups, where N2, CO2, H2, and CH4 gases vapors and polar H2O, MeOH, and EtOH molecules reversibly adsorbed into the networks. The molecular motion of polar H2O was directly observed in dielectric enhancement and protonic conductivity in three-dimensional O–H···O hydrogen-bonding networks. The Brunauer–Emmett–Teller (BET) specific surface areas of amorphous 1 and 2 were 315 and 351 m2 g–1, respectively, from the CO2 sorption isotherms. Reversible vapor sorption behaviors with structural changes of amorphous 1 and 2 were also confirmed for the polar H2O, MeOH, and EtOH.