Hydrogen-bond-promoted native lignin degradation via PCET process enabled by visible light

Toward the development of sustainable resources, the degradation of lignin presents an opportunity for the valorization of biomass into valuable chemicals and fuels. In this study, we develop an approach utilizing 2-bromo-anthraquinone (2-Br-AQN) as a green and cost-effective organic photocatalyst. This methodology succeeds in degrading six different sources of native lignin under visible-light conditions. The degradation process follows a redox-neutral pathway, eliminating the requirement for additional oxidants, bases, and transition metals. This characteristic enhances the environmental friendliness of the process, making it more sustainable. Mechanistic studies and density functional theory (DFT) calculations suggest that the reaction involves a hydrogen-bond-promoted proton-coupled electron transfer (PCET) process. [Display omitted] •Six different sources of native lignin are degraded•No requirement for additional oxidants, bases, or transition metals•Inexpensive and commercially available small-molecule organic catalyst is used•Hydrogen-bond-promoted PCET process for O–H activation is proposed Converting lignin into valuable chemicals and fuels is of interest as a sustainable alternative to producing them with fossil fuels. Zheng et al. use organic small molecules to activate O–H bonds via hydrogen bonding, facilitating Cα–Cβ bond cleavage in lignin degradation, and validate the method on six different sources of lignin.