Functional Metallocenes as Cofactors Promote the Catalytic Performance of Mimetic Enzymes

Abstract Coenzymes (cofactors) are essential for bio‐redox reactions, group transfer reactions, and heterogeneous reactions of bio‐enzymes, as well as the auxiliary transfer of electrons or atoms to promote bio‐enzyme activity. However, when mimetic enzymes are scaled to the micro or nanoscale levels, both the absence of cofactor activity and the presence of migrating internal atoms cause self‐depletion, eventually limiting sustained usage. Herein, cofactor regulation, a key issue long neglected in traditional mimetic enzyme construction is addressed. In particular, the construction of a mimetic enzyme with monomeric ferrocene is reported. The artificial enzyme consists of both a catalytic center (Fe 2+/3+ ) and a proximate structural unit (functional cyclopentadienyl). The reducing properties of cyclopentadienyl are used as a cofactor to decrease activation energy required to catalyze Fe 3+ to Fe 2+ , lower energy barriers to increase recycling, and, finally, promote electron transfer. This ferrocene‐based mimetic enzyme can achieve non‐depletion cycle catalysis by keeping the structures and properties of the enzyme constant after the catalytic reaction. Thus, this in situ self‐assembly construction of mimetic enzymes using functionalized proximate structural units as cofactors offers a niche concept to solve the predicament of self‐depletion such as that seen in traditional mimetic enzymes.