In biological systems, efficient gas transport is enabled by hemoglobin, a protein that binds cooperatively to oxygen. The four binding sites of hemoglobin are coupled through conformational changes in the protein scaffold, such that binding at one site influences the binding affinity of the remaining sites. Inspired by hemoglobin, we developed a synthetic system that exhibits cooperativity, but that binds carbon dioxide rather than oxygen. Specifically, our system employs chelate cooperativity wherein binding of the first CO2 molecule reduces the entropic cost of binding the second molecule. We highlight design principles for enhancing the chelate effect and discuss how cooperativity at the molecular level translates to bulk thermodynamic properties. Understanding how to elicit cooperative CO2 is key to designing new materials that transition between high-affinity and low-affinity binding, allowing CO2 to be both easily bound and easily released.

CO2 binding employing chelate cooperativity

249th National Meeting (2015)

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