Synergistic Engineering of Pyrene–Thiazolothiazole-Based Donor−π–Acceptor Conjugated Microporous Polymers with Heteroatom Embedding for Efficient Visible-Light Photocatalyst for Organic Dye Degradation
Yang‐Chin Kao, Mohamed Gamal Mohamed, Yinghong Chen, Mohsin Ejaz, Shiao‐Wei Kuo
Abstract
High Resolution Image Download MS PowerPoint Slide Water pollution caused by organic dyes poses a significant threat to ecosystems and human health, underscoring the urgent need for sustainable degradation methods. We report two donor−π–acceptor conjugated microporous polymers (CMPs), Pyr-Ph-TzTz and Pyr-Th-TzTz, assembled from pyrene (Pyr) donors, phenyl or thiophene π-bridges, and thiazolothiazole (TzTz) acceptors. Precursors [4,4′,4″,4‴-(pyrene-1,3,6,8-tetrayl)tetrabenzaldehyde (Pyr-Ph-4CHO) and 5,5′,5″,5‴-(pyrene-1,3,6,8-tetrayl)tetrakis(thiophene-2-carbaldehyde) (Pyr-Th-4CHO)] were synthesized via electrophilic bromination and Suzuki–Miyaura coupling with 4-formylphenylboronic acid (PFPBA), and 5-formyl-2-thienylboronic acid (5-FTBA); respectively. Pyr-Ph-4CHO and Pyr-Th-4CHO were each subjected to a one-pot condensation reaction with dithiooxamide, yielding robust, thermally stable CMPs─Pyr-Ph-TzTz and Pyr-Th-TzTz─with amorphous frameworks and surface areas of 37 and 20 m 2 g –1, respectively. UV–vis spectra reveal narrow band gaps of 2.02 eV for Pyr-Ph-TzTz CMP and 2.39 eV for Pyr-Th-TzTz CMP. Pyr-Ph-TzTz CMP exhibits markedly enhanced charge separation, as evidenced by pronounced PL quenching and ultraviolet photoelectron spectroscopy (UPS) analysis. Both CMPs adsorb rhodamine B (RhB) rapidly (equilibrium in 30 min; 55% removal by Pyr-Ph-TzTz CMP, 90% by Pyr-Th-TzTz CMP) and degrade it under visible light, achieving 96% ( k = 0.0545 min –1 ) and 39% ( k = 0.00341 min –1 ) removal, respectively. Radical scavenging and EPR identify •OH as the primary active species. Remarkably, Pyr-Ph-TzTz CMP retains >90% activity after five cycles, highlighting its promise for solar-driven dye removal.