Supramolecular aggregates consist of molecular sub-units (i.e. monomers) that self-assemble under thermodynamic equilibrium conditions into close-packed (i.e. aggregated) molecules via weak (i.e. non-covalent) interactions. Though the forces behind self-assembly (e.g. hydrophobicity) are known, the specific mechanism by which monomers form the supramolecular aggregates still remains an open question. A crucial step towards formulating a complete mechanism is understanding the role of the monomer’s counter ion in the self-assembly process. Here this question is addressed by means of a well-defined artificial model system: supramolecular light-harvesting nanotubes (LHNTs) self-assembled from cyanine-dye molecules (figure). Even though this system has been intensively studied [1,2,3,4], the details of the self-assembly process are still not understood. In this study, counter ions with varying properties (e.g. polarizability) were employed to determine their role in the LHNTs' self-assembling process. Currently, LHNTs are known to form two different morphologies: individual double-walled nanotubes and bundles of single-walled nanotubes [4]. In this study, it was found that while the size of the counter ion affects the morphological details, the rate of formation of bundles of LHNTs is directly correlated with the counter ion concentration. [1] D.M.Eisele et al., Nature Chem. 2012; [2] D.M.Eisele et al., JACS 2010; [3] D.M.Eisele et al., Nature Nanotech. 2009; [4] D.M.Eisele et al., PNAS 2014

Discerning the effect of counter ions on supramolecular self-assembly

251st National Meeting (2016)

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