Fluorenone and Fluorenemalononitrile‐Tethered Conjugated Microporous Polymers for Efficient CO 2 Uptake and Rhodamine B Removal

ABSTRACT Herein, two conjugated microporous polymers (CMPs), TPET‐FO and TPET‐F2CN, are functionalized with carbonyl and nitrile groups. These porous networks are constructed via the Sonogashira coupling reaction, using 1,1,2,2‐tetrakis(4‐ethynylphenyl)ethene (TPET) as a tetrahedral core, which is coupled with 2,7‐dibromo‐9H‐fluoren‐9‐one (FO‐2Br) and 2‐(2,7‐dibromo‐9H‐fluoren‐9‐ylidene)malononitrile (FL‐2CN‐2Br), respectively. Both CMPs possess well‐developed porosity, as evidenced by their Brunauer–Emmett–Teller surface areas (S BET ) of 508 m 2 g −1 for TPET‐FO CMP and 682 m 2 g −1 for TPET‐F2CN CMP. Among the two materials, the TPET‐F2CN CMP exhibits markedly superior performance. It demonstrates enhanced CO 2 uptake capacities of 1.69 and 2.88 mmol g −1 at 298 and 273 K, respectively, significantly exceeding those of the TPET‐FO CMP (0.96 and 1.60 mmol g −1 under identical conditions). In addition, TPET‐F2CN CMP shows outstanding adsorption behavior toward rhodamine B (Rhd B), with an equilibrium adsorption capacity ( q e ) of 98.12 mg g − 1 and a maximum monolayer capacity ( q m ) of 155.6 mg g − 1 , as determined by the Langmuir model. These values are substantially higher than those observed for TPET‐FO CMP. Interaction Region Indicator (IRI) analysis indicated that the adsorption performance of TPET‐F2CN CMP toward CO 2 and Rhd B is mainly promoted by stronger non‐covalent interactions and enhanced delocalization of π‐electrons in TPET‐F2CN CMP.