Aggregation induced emission and amplified explosive detection of tetraphenylethylene-substituted polycarbazoles

Abstract

Novel conjugated polymers based on 3,6-carbazole repeat units were synthesized by nickel-catalyzed Yamamoto coupling under microwave heating. The resulting poly(3,6-carbazole)s contain tetraphenylethylene (TPE) units in their side chains. The resultant polymers show aggregation induced emission (AIE) behavior. Hereby, the photoluminescence (PL) intensity of PCzTPE0.5 in 90% water–THF is 35 times higher than that in pure THF, connected to the introduction of TPE side chains. The ability of polymer PCzTPE0.5 for explosive sensing was also studied. A maximum Stern–Volmer quenching constant of 1.26 × 10⁶ M⁻¹ was observed for PL quenching of PCzTPE0.5 aggregates by trinitrobenzene (TNB). A solid state paper strip test based on PCzTPE0.5 and PCzTPE also demonstrates effective PL quenching towards both TNB vapor and solution.