High pH and Temperature Tolerant Molecular Mimic of Carbonic Anhydrase for Self-Healing Cementitious Material

Carbon storage in concrete was recently reinvigorated by the use of carbonic anhydrase to yield an enzymatic self-healing cementitious material. While this material demonstrates high strength and self-healing properties, the reliance on enzymatic catalysis limits the performance based on the two-week lifetime of carbonic anhydrase, and motivates the exploration of non-biological alternatives. We have explored organometallic carbonic anhydrase mimetic materials with a view towards longevity and performance in the highly alkaline environments of cement as well as the high temperatures to which concrete may be subjected. Inspired by bio-relevant carbonic anhydrase mimetics, results with zinc cyclen (cyclen = 1,4,7,10-tetraazacyclododecane) demonstrate high stability at pH above 13 and temperatures above 50 °C with good conversion of gas-phase carbon dioxide to carbonate. We discuss these results in the context of molecular alternatives for self-healing cementitious material and carbon storage in concrete.