Sustaining Radicals in Aqueous Media Through Formation of a Trigger-Inclusive Microenvironment in Hydrogen-Bonded...

The stabilization of radical species in aqueous environments remains a central challenge for radical-based antibacterial applications, as rapid quenching severely limits its efficacy. Herein, we report a strategy to sustain radical by coupling diffusional confinement with electronic delocalization in π-conjugated hydrogen-bonded organic frameworks (HOFs). Using a pyrene-based HOF (PFC-1) as a model system, we systematically modulate the longitudinal dimensions of 1D channels to generate frameworks with three distinct aspect ratios while maintaining topology. The higher-aspect-ratio channels impose a more pronounced kinetic barrier to the outward diffusion of radical-generating trigger (ceric ammonium nitrate), thereby retaining a trigger-inclusive oxidative microenvironment. Simultaneously, the extended π-π stacking enhances electronic delocalization, stabilizing the resulting radicals through favorable host-guest interactions. As a result, radicals confined within the longest-channel framework remain persistent for over 30 days in water and up to 8 months under ambient conditions. This prolonged radical persistence enables potent antibacterial activity against Escherichia coli via radical-induced oxidative stress. This work establishes a trigger-inclusive microenvironment capable of simultaneously retaining both the radical species and its trigger as a generalizable design principle for engineering persistent radical states.