Visualization of Electron and or Energy Transfer in Redox Active Polymeric Colloids*

Under the scenario of size-exclusion mechanism flow battery, viologen-based polymeric colloids demonstrate efficient and reversible charge transport in aqueous and non-aqueous environments. We believe there is tremendous power in visualization of the corresponding contact-mediated electron and or energy transfer between these colloids, which will provide a more intuitive understanding of the unique dynamics as well as facilitate redox-state mapping in the system. Intrinsic electrofluorochromism of the redox active colloids (RAC) was discovered and exploited to serve the purpose. Via coupling a distinct fluorescent contrast with the respective redox state we successfully in-situ imaged intra- and inter-colloid energy transfer processes during electrochemical cycling. This system also displayed a greater than hundred-fold amplification of the sensitivity to fluorescence quenching. Photophysics of the amplification was further investigated and we attributed it to fast electron hopping among neighboring redox groups.