Bifunctional imidazolium linked tetraphenylethene based conjugated microporous polymers for dynamic antibacterial properties and supercapacitor electrodes

Abstract

Conjugated microporous polymers (CMPs) present intriguing potential for a myriad of applications. In this study, we detail the synthesis of bimine-linked conjugated microporous polymers (CMPs), namely TPET-Bimine and PT-Bimine CMPs, through Sonogashira–Hagihara cross-coupling. The process involves coupling the (1E,2E)-N¹,N²-bis(4-bromophenyl)ethane-1,2-diimine (Bimine-B_r2) building block with 1,1,2,2-tetrakis(4-ethynylphenyl)ethene (TPET) and 1,3,6,8-tetraethynylpyrene (PT) units, followed by partial post-cyclization into an imidazolium (Im)-linked CMP (TPET-Im and PT-Im CMPs). Our investigation covers thermal stability, molecular structure, porous characteristics, and potential applications of these novel CMPs using various analytical techniques. Notably, TPET-Bimine CMP demonstrates superior thermal stability (T_d10 = 390 °C) with a char yield of 67 wt% and the highest BET surface area of 451 m² g⁻¹ compared to the other samples. The antibacterial activities and electrochemical performance of all synthesized CMPs were assessed. Im-linked CMPs exhibited enhanced antibacterial activity and improved electrochemical capacitance compared to the pristine samples without the imidazolium ring. The cationic linkage facilitates a robust interaction with bacterial membranes, enhancing antibacterial efficacy, particularly against Staphylococcus aureus (S. aureus). Antibacterial activity increased with higher concentrations of Im-linked CMPs; for instance, PT-Im and TPET-Im CMPs showed the highest antibacterial activity at 15 mg mL⁻¹. Cytotoxicity evaluation against L929 fibroblasts demonstrated good compatibility in the presence of Im-linked CMPs. Additionally, TPET-Im CMP displayed the highest specific capacitance of 63 F g⁻¹, coupled with an energy density of 8.73 W h Kg⁻¹ in supercapacitive studies. These results highlight the potential applications of Im-linked CMPs as both antibacterial agents and electrode materials for supercapacitors.