Preparation, Characterization, and Structure Trends for Graphite Intercalation Compounds Containing Pyrrolidinium Cations

New graphite intercalation compounds (GICs) containing N,N-n-alkyl substituted pyrrolidinium cation intercalates (Py-n,Py-m, n, m = alkyl chain lengths) are obtained via cationic exchange from stage-1 donor-type GIC [Na-(ethylenediamine)(1.0)]C-15. Powder X-ray diffraction and thermogravimetric analyses are used to determine the GIC structures and compositions. [Py-4.8]C-47 center dot 0.71DMSO and [Py-8.8]C-48 with intercalate monolayers are obtained as stage 1 GICs with gallery expansions of 0.48 nm, whereas [Py-1.18]C-47 and [Py-12.12]C-80 center dot 0.25DMSO form stage-1 GICs with intercalate bilayers and gallery expansions of 0.81 nm. The gallery dimensions require that alkyl chain substituents orient parallel to the encasing graphene sheets. Smaller intercalate cations such as Py-1.4, Py-4.4 and Py-1.8 either form high-stage GICs or do not form stable intercalation compounds. These results, along with those reported for graphite intercalation of Other quaternary ammonium cations, indicate trends in graphite chemistry where larger intercalates form more stable and lower-stage, GICs, and the graphene sheet charge densities can be correlated to the intercalate footprint areas.