Light-mediated CO2-responsiveness of metallopolymer microgels

Here, we report a finding on light-mediated CO2-responsiveness. It is found on the microgels that are made of side-chain type metallopolymers containing metalla-aromatics. Turbidity and laser light scattering studies on dilute aqueous dispersion of these microgels in dark indicate high CO2-responsivity, but poor reversibility upon N2purge, which can be improved by exposing to light. This light-mediated CO2-responsiveness can be elucidated by the loss of aromaticity from initial photoexcitation and concurrent formation of a less reactive, antiaromatic excited state of relatively low CO2binding affinity, and by subsequent relief of antiaromaticity that can enhance the CO2removal. The finding is also checked by CO2uptake-release experiments on the microgels, which enables both CO2capture of high capacity and CO2removal of good reversibility under a mild condition, allowing effective and reversible response to dilute CO2.