Synthesis and structural investigation of new graphite intercalation compounds containing the perfluoroalkylsulfonate anions C10F21SO3-, C2F5OC2F4SO3-, and C2F5(C6F10)SO3-

摘要

The preparation of graphite intercalation compounds (GIC's) of three perfluorinated alkylsulfonate anions, C10F21SO3-, C2F5OC2F4SO3- and C2F5(C6F10)SO3- is described for the first time. Pure stage 2 GIC's are obtained by chemical oxidation of graphite with K2MnF6 in a solution containing hydrofluoric and nitric acids for 72 h. One-dimensional electron density maps derived from powder diffraction data are fit to obtain models for the intercalate gallery structures: the structure models provide details on anion concentrations, orientations, and conformations. In all cases, anion bilayers are observed with anion sulfonate headgroups oriented towards graphene sheets. Compared with structures calculated for the isolated anions, the intercalated anion conformations show changes in dihedral angles, involving rotations about C-C or C-O bonds. For the GIC containing C2F5(C6F10)SO3-, the anion conformation change is related to the more efficient packing of anions in the intercalate gallery. (C) 2004 Elsevier Ltd. All rights reserved.