Regulating Enol-to-Keto Tautomerization of Pillararene-Based Conjugated Macrocycle Polymers for H2O2 Photosynthesis

Abstract

Porous organic polymers have emerged as promising materials for energy conversion, pollutant adsorption, and heterogeneous catalysis because of their tunable pore structures and high surface areas. However, most porous organic polymers are still limited by insufficient conjugation and inefficient electron–hole separation, hindering the tunability of their photoelectric properties and overall functionality. By integrating macrocyclic compounds as a new building block, which feature electron-rich cavities and rigid ring structures, into the polymer network, the resulting conjugated macrocycle polymers are expected to provide an innovative approach to enrich the photoelectric functionalities of porous organic polymers. Herein, an enaminone-based pillararene photocatalyst, TpAP[5], is constructed by covalently linking functionalized pillar[5]arene to conjugated macrocycle polymers through Schiff base condensation for efficient photocatalytic reactions. This material demonstrates exceptional performance in the photocatalytic production of hydrogen peroxide, achieving a rate of 2343 μmol g^–1 h^–1. In-depth investigations reveal that the incorporation of pillararenes enables synergistic catalysis of water oxidation and oxygen reduction reactions and significantly enhances catalyst stability by regulating molecular tautomerization. This work opens new avenues for designing high-performance multifunctional conjugated macrocycle polymers with significant potential for clean energy conversion.