Efficient liquid exfoliation and dispersion formation of alkyl-terminated germananes

We report a simple preparation method for dispersions of alkyl-terminated germananes, GeC n H 2n+1 (n = 1, 3, 6, 8, and 12), in halogenated solvents. The dispersion efficiency and suitable solvent were strongly dependent on the terminal alkyl-chain length; with appropriate combinations of alkyl-chain length and solvent identity, liquid exfoliation was achieved not only by ultrasonication but even by simple mechanical stirring at room temperature. Sufficiently long alkyl chains facilitated exfoliation by expanding the interlayer spacing; however, the dispersion concentration did not simply increase monotonically with alkyl-chain length. These results indicate that the behavior of dispersions is governed by a balance among interlayer expansion, solvent affinity for the alkyl-chain region, and kinetic processes such as reaggregation and sedimentation. This mild and practical method may provide a useful route toward solution processing of alkyl-terminated germananes.