Cellulose Depolymerization with LPMO-inspired Cu Complexes

Bis(benzimidazole)amine-based copper complexes, with structural similarities to the active sites of Lytic Polysaccharide Monooxygenase enzymes (LPMOs), were tested for the oxidative degradation of cellulose. Spectroscopic characterization of the complexes, as well as structural authentication of one of them, confirm a tetragonal coordination environment with 3 nitrogen donors, as well as a thioether in axial positions. Aqueous oxidative degradation of cellulose was achieved with the Cu-II complexes and H2O2 as oxidant through putative cupric-hydroperoxo intermediates. Conversion of cellulose was achieved in up to 67 % yield of soluble oligosaccharide derivatives at ambient temperature and pressure. The products were analyzed in aqueous solution by HPLC-MS, confirming oxidative depolymerization of cellulose under ambient conditions, in an analogous fashion to LPMOs.

Automated summary

The study demonstrates that copper complexes based on bis(benzimidazole)amine can effectively oxidatively degrade cellulose, achieving up to 67% yield of soluble oligosaccharide derivatives, providing a potential method for cellulose degradation.