Controlled Immobilization of a Palladium Complex/Laccase Hybrid into a Macrocellular Siliceous Host

This study investigates the site-directed immobilization of a hybrid catalyst bearing a biquinoline-based-Pd(II) complex (1) and a robust laccase within cavities of a silica foam to favor veratryl alcohol oxidation. We performed the grafting of 1 at a unique surface located lysine of two laccase variants, either at closed (1 subset of UNIK157) or opposite position (1 subset of UNIK71) of the enzyme oxidation site. After immobilization into the cavities of silica monoliths bearing hierarchical porosity, we show that catalytic activity is dependent on the orientation and loading of each hybrid, 1 subset of UNIK157 being twice as active than 1 subset of UNIK71 (203 TON vs 100 TON) when operating under continuous flow. These systems can be reused 5 times, with an operational activity remaining as high as 40 %. We show that the synergy between 1 and laccase can be tuned within the foam. This work is a proof of concept for controlling the organization of a heterogeneous hybrid catalyst using a Pd/laccase/silica foam.

Automated summary

This study investigates the site-directed immobilization of a hybrid catalyst bearing a biquinoline-based-Pd(II) complex and a robust laccase within cavities of a silica foam to favor veratryl alcohol oxidation. The catalytic activity is dependent on the orientation and loading of each hybrid, and the system can be reused multiple times with a high operational activity remaining. The work demonstrates the concept of controlling the organization of a heterogeneous hybrid catalyst using a Pd/laccase/silica foam.