Luminescent Conjugated Microporous Polymers for Selective Sensing and Ultrafast Detection of Picric Acid

Abstract

Luminescent conjugated microporous polymers (CMPs) are one of the important class of porous organic materials that possess a fully π-conjugated skeleton and high surface area and have been utilized as light-emitting materials. In this work, we have designed and developed three luminescent CMPs based on truxene core (Tx-CMPs) via Suzuki–Miyaura cross-coupling reaction in one step. The flexible aryl linker in Tx-CMPs prevents the possibility of aggregation-caused quenching (ACQ) due to π–π stacking of layers and thus offers a high luminescence in the synthesized Tx-CMPs. All Tx-CMPs possess a high BET surface area (SBET = 788–915 m2 g–1) and excellent thermal stability. Utilizing the fluorescent nature and electron-rich property of the Tx-CMPs, we exploited them as a sensor for the selective and sensitive detection of picric acid (PA) among various nitroaromatic explosives. The Stern–Volmer constant (KSV) for PA was estimated as 3.97 × 104, 7.35 × 104, and 2.39 × 104 M–1 for Tx-CMP-1, Tx-CMP-2, and Tx-CMP-3, respectively, indicating that PA can quench the fluorescence intensity of Tx-CMP-2 most efficiently. The detection limits of Tx-CMPs toward PA were found in the nanomolar range.