While the ground- and excited-state electronic properties of dye assemblies are primarily regulated by the interaction modes of functional building blocks, strategies to modulate dispersion forces between repeating units have mainly focused on the design and synthesis of monomers. Deviating from conventional approaches, we present a two-component stapling method to tether π-conjugated supramolecular polymers derived from water-soluble perylene bisimides with molecular tethers equipped with increased structural rigidity. The structurally well-defined nanoscale objects created in this manner possess ground- and excited-state electronic properties that are intimately related to the structures of the molecular tethers. Using Coulomb coupling as spectroscopic reporters, we show that non-covalent assemblies stapled with short, more rigid tethers possess a robust ground-state electronic structure that is insensitive to changing temperature (274 K to 368 K). Interrogating the excited state dynamics of stapled structures using ultrafast transient absorption measurements highlights their structural rigidity. Photoexcitation of the stapled assemblies initiates the formation of excited states with mixed Frenkel exciton and charge transfer character. Our data indicate that the charge transfer contributions to these states can be enhanced by increasing the structural rigidity of the stapled assemblies, providing a potential pathway for separating charge for light harvesting applications. Furthermore, deriving these solution-based superstructures to the solid state enables the formation of hierarchical nano- to mesoscale platforms whose exciton diffusion coefficients measured by time-resolved microscopy rival these reported for crystalline materials. Overall, the results presented delineate new tools to extrinsically modulate the ground- and excited-state electronic properties of conventional π-conjugated assemblies and pave the way to new classes of well-defined nanoscale objects equipped with appealing (opto)electronic properties.

Modulating the ground- and excited-state electronic properties of structurally well-defined nanoscale objects by stapling π-conjugated supramolecular polymers

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.