Electroenzymatic cascade reaction on a biohybrid boosts the chiral epoxidation reaction

Abstract

The chiral epoxidation of styrene and its derivatives is an important transformation that has attracted considerable scientific interest in the chemical industry. Herein, we integrate enzymatic catalysis and electrocatalysis to propose a new route for the chiral epoxidation of styrene and its derivatives. Chloroperoxidase (CPO) functionalized with 1-ethyl-3-methylimidazolium bromide (ILEMB) was loaded onto cobalt nitrogen-doped carbon nanotubes (CoN@CNT) to form a biohybrid (CPO-ILEMB/CoN@CNT). H2O2 species were generated in situ through a two-electron oxygen reduction reaction (2e–ORR) at CoN@CNT to initiate the following enzymatic epoxidation of styrene by CPO. CoN@CNT had high electroactivity for the ORR to produce H2O2 at a more positive potential, prohibiting the conversion of FeIII to FeII in the heme of CPO to maintain enzymatic activity. Meanwhile, CoN@CNT could serve as an ideal carrier for the immobilization of CPO-ILEMB. Hence, the coimmobilization of CPO-ILEMB and CoN@CNT could facilitate the diffusion of intermediate H2O2, which achieved 17 times higher efficiency than the equivalent amounts of free CPO-ILEMB in bulk solution for styrene epoxidation. Notably, an enhancement (∼45%) of chiral selectivity for the epoxidation of styrene was achieved.