Effect of functionalization on axially substituted 2,7-pyrene covalent triazine frameworks for dual sensing applications

To advance the critical goal of selective pollutant detection for environmental remediation, we have developed two classes of covalent triazine frameworks (CTFs). The first incorporates a 2,7-pyrene moiety, resulting in a donor-acceptor CTF, while the second type has a donor-(π-spacer)-acceptor configuration through the integration of pyrene-aryl or pyrene-fluoroaryl-1,3,5-triazine units (2,7-arylPyr-CTFs). Additionally, a partially fluorinated CTF (CTFmix) was synthesized by co-polymerizing fluorinated and non-fluorinated dinitrile monomers. All CTFs were obtained via acid-catalyzed cyclotrimerization and thoroughly characterized using different spectroscopic and analytical techniques. Giving the high chemical stability, enhanced light-harvesting ability, and efficient charge separation and transfer properties of pyrene-based-CTFs, we have investigated the influence of functional groups, particularly fluorine, on their environmental analyte sensing. Our results show that these Pyrene-CTFs are effective fluorescent probes for the selective detection of picric acid (PA) and the pesticide dicloran (DCNA). Among then, the mixed fluorinated CTF, exhibited the highest sensitivity, achieving detection limits in the ppm range. Furthermore, this material showed high selectivity towards metal ions such as Au 3+ or Fe 3+ , with fluorescence recovery observed up to six cycles upon the addition of ascorbic acid. • Two series of pyrene-based CTFs with D–A and D–π–A configurations were designed to enhance charge separation and transfer. • A mixed CTF, combining fluorinated and non-fluorinated monomers, results in superior sensitivity for pollutant detection. • Pyrene-CTFs showed fluorescent sensing of of picric acid (PA) and dicloran (DCNA), with detection limits in the ppm range. • Fluorinated CTF showed selectivity for Au³⁺ and Fe³⁺, with fluorescence recovery after six cycles with ascorbic acid. • Their chemical stability, light harvesting, and sensing make these CTFs promising for environmental applications.