Donor–Acceptor Pyrrolo[3,2-<i>b</i>]pyrrolyl- and Dibenzothiophene-Containing Microporous Polymeric Frameworks for Photocatalytic Organic Pollutant Degradation

Conjugated microporous polymers (CMPs) are potential photocatalysts for pollutant remediation, but their undesirable energy band structure limits their practicality. This paper presents the efficient, metal-free, and environmentally benign synthesis of donor–acceptor pyrrolo[3,2-b]pyrrolyl and dibenzo[b,d]thiophene-based CMPs (DBTO-CMP-1 and DBTO-CMP-2) through cyclization processes involving 3,7-diaminodibenzo[b,d]thiophene 5,5-dioxide (DBTO-2NH2), aryl aldehydes, and a 2,3-butadione aimed at the effective photocatalytic degradation of the organic pollutant RhB. The electrical band gap, electrochemical, and photophysical properties of such polymers can be meticulously adjusted by choosing appropriate aldehydes. The resulting DBTO–CMP frameworks demonstrate impressive porosity, semicrystalline nature, and an enlarged surface area of 140 m2 g–1, along with notable thermal endurance. For application, the DBTO–CMP frameworks demonstrate high-performance catalytic activity for the photodegradation of organic dye RhB with reusability. Specifically, RhB can undergo complete photodegradation by DBTO–CMP-1 when subjected to UV–visible light exposure within a span of 3 h, achieving a degradation efficiency of 97.27%. The investigation into the mechanism provides compelling evidence that the efficient photodegradation facilitated by ADBTO–CMP-1 can be chemically elucidated through the presence of superoxide radicals. Furthermore, the phytotoxicity assessment conducted on the bean sprouts reveals that the degradation products of RhB exhibit nontoxic properties and facilitate the growth of bean sprouts. This synthetic technique allows the synthesis of metal-free, easily produced polymeric materials with excellent catalytic properties.