Cooperative Supramolecular Polymerization in Both Polar and Non-Polar Solvents via Heteroatom-Driven Amphiphilicity

Supramolecular polymers in water and non-polar solvents are extensively studied as model systems to mimic biological processes and as functional materials, respectively. The molecular designs to obtain supramolecular polymers in non-polar and polar solvents are typically orthogonal. Here, we disclose a molecular design in which we combine hydrogen-bonding amide units attached to alkyl chains for compatibility with non-polar solvents and heteroatom in the π-conjugated core for interaction with polar solvents, leading to supramolecular polymerization of the same monomeric unit in both non-polar and mixture of polar solvents. Redox-active phenazine appended with two amide groups was studied as a model monomeric unit and it undergoes cooperative polymerization via intermolecular hydrogen-bonding resulting in one-dimensional (1D) nanostructures with co-facial type packing in non-polar solvents. Whereas, in a mixture of polar solvents, a J-type packing was observed with tunable morphology from globular to 1D nanostructures based on the polarity of the cosolvent used. Further, solvent isotopic substitution studies suggest that the amphiphilicity of the system can be attributed to the nitrogen-atom in phenazine, which is capable of interacting with polar solvent molecules. Thus, this study opens up azaacenes as a new class of π-conjugated units for functional supramolecular polymers.