Pathway Control in Cooperative vs. Anti-Cooperative Supramolecular Polymers

Controlling the nanoscale morphology in assemblies of pi-conjugated molecules is key to developing supramolecular functional materials. Here, we report an unsymmetrically substituted amphiphilic Pt-II complex 1 that shows unique self-assembly behavior in nonpolar media, providing two competing anti-cooperative and cooperative pathways with distinct molecular arrangement (long- vs. medium-slipped, respectively) and nanoscale morphology (discs vs. fibers, respectively). With a thermodynamic model, we unravel the competition between the anti-cooperative and cooperative pathways: buffering of monomers into small-sized, anti-cooperative species affects the formation of elongated assemblies, which might open up new strategies for pathway control in self-assembly. Our findings reveal that side-chain immiscibility is an efficient method to control anti-cooperative assemblies and pathway complexity in general.