Molecular pillar supported graphene oxide framework: conformational heterogeneity and tunable d-spacing†
n-Alkylamines were grafted on the basal plane oxygen functionalities of graphene oxide (GO), yielding molecular pillar supported graphene oxide frameworks (GOFs) with tunable interlayer spacing. A major fraction of n-alkylamines was found to covalently interact with the basal plane epoxy groups via nucleophilic substitution reactions. The d-spacing in GOFs could be tailored between 10.5 and 28.9 Å by varying the chain length of the n-alkylamines. 13C SSNMR explicitly showed the coexistence of both trans and gauche conformation modes. The relative populations of these modes control the conformational heterogeneity and orientation of n-alkylamines in the GOFs. A plausible bilayer structural model of the GOFs was demonstrated. The terminal methyl and methylene units of the n-alkylamines grafted on the GO basal plane were interdigitated with the counter layer and afforded a double-layer structure of alkyl chain supported GOFs.