Regulating Light Absorption, Charge Orientation, and Oxygen Activation of Conjugated Porous Polymers for Photocatalytic Organic Synthesis.

Conjugated porous polymers (CPPs), featuring π-conjugation systems, freedom in molecular structural design, and intrinsic porosity, have emerged as a modular platform for visible-light-driven organic synthesis. At present, their photocatalytic efficiency is limited by incomplete absorption of visible light, inefficient charge separation, and inadequate management of oxygen-active species, urging the field to explore solutions. Light absorption can be strengthened by molecular engineering strategies, e.g., extension of π-conjugation, adjustment of donor-acceptor units, and incorporation of chromophores, e.g., triazine and phenothiazine, that redshift and thus broaden the absorption. Charge separation can intensify by integration of donor-acceptor segments and π-bridged linkers to cut exciton binding energy and extend lifetime of carriers; migration of charge carriers can be more directed by introduction of polar substituents and localized dipoles. Along with modifying the bandgap structure, modulation of the catalytic microenvironment can shape selective substrate activation, for instance, framework rigidification, control of electronic structure of active sites, and spatial confinement of intermediates. In terms of handling oxygen-active species, we can regulate charge distribution and electronic structure within the conjugated backbone. This regulation enhances formation of reactive intermediates such as superoxide, hydroxyl radical, and other essential oxygen-derived species to drive oxidative photocatalytic processes. Together, these approaches establish a coherent design scheme to develop high-performance, metal-free photocatalysts for diverse organic synthesis and sets a foundation for future sustainable catalysis and synthesis of photoresponsive materials.