Enzyme-Graphene Nanometal biohybrid Architectures as Highly Efficient Multifunctional Catalysts for Cascade Reactions

Abstract

The development of new catalytic systems with different chemo- and biocatalytic functionalities for sustainable one-pot multistep transformations represents a big challenge in modern chemistry. Here, we have designed and synthesized novel enzyme-graphene nanometal hybrids of palladium and copper as multiactive heterogeneous catalysts. The in-situ formation of metallic nanoparticles of different size and species on enzymes (C. antartica lipase, CALB and and T. lanuginosus lipase), TLL) immobilized on multilayer graphene-anchored enzymes (G@CALB and G@TLL preparations) at room temperature and aqueous media allowed to create different kind of enzyme-metal nanoarchitectures, containing up to two enzymes and metallic nanoparticles of two different metals in the same compartment. The metallic nanoparticles were synthesized exclusively induced by the enzyme, homogeneously distributed on the enzymatic structure used as scaffold. The cooperative and synergistic participation of different chemo and biocatalytic components in the reduction process and especially in different cascade reactions was demonstrated. Domino cascade in aqueous media (enzymatic hydrolysis, metal reduction, and metal oxidation) was successfully performed from the different hybrid systems. The synthesis of glycoderivatives, transforming selectively peracetylated glucal to novel disaccharides, using G@CALB-Cu3(PO4)2NPs and G@CALB-Cu(0)NPs or α-peracetylated glucose to diacetyl-gluconic acid by G@TLL@CRL-Cu3(PO4)2NPs was successfully performed. Finally, the successful application in the dynamic kinetic resolution of racemic arylamine (>99% conversion and ee) in organic solvent catalyzed by G@CALB-Pd(0)NPs-Cu3(PO4)2NPs demonstrated the potential effect in synthetic chemistry, and the synergistic effect of catalysis between enzyme and metals. Furthermore, recycling studies demonstrated the high robustness of them.