Long-Range Quantitative Multi-VOC Fluorescence Sensing Enabled by Donor-Carborane-Acceptor Assembly

Developing single sensors capable of sensing multiple volatile organic compounds (VOCs) by quantitative fluorescence (QF) is highly desirable and is required to cover distinct analytes across different concentration levels. Current multi-VOC sensors based on polymers or oligomers suffer from two major drawbacks, whereas the exploitation of ideal multi-VOC sensors based on small molecules is still challenging. In this work, three donor-carborane-acceptor sensors (Cb-FL/Cb-NE/Cb-NA) with aggregation-induced emission and through-space charge transfer (TSCT) potential were developed. These sensors were assembled in centrosymmetric dimers in the crystals and in consistent aggregates in the films. In the sensing of trace VOCs, the film-based Cb-FL and Cb-NE showed a particular emission-off response to amines, while Cb-NA showed an evident emission-off response (>1% at 2 g/m3) to seven distinct analytes, including toluene, diethyl sulfide, dipropylamine, with the QF sensitivity maintained in 3 orders of magnitude in concentration (178 mg/m3–88.93 g/m3 at most) and good discrimination of homologous VOCs under a fixed concentration. Moreover, fast response/recovery in 16–60/8–15 s and low detection limits of 178–209 mg/m3 were achieved in the multi-VOC sensing by Cb-NA. Theoretical modelings showed that Cb-NA harvested TSCT in single molecules dissociated from the consistent dimers and proceeded with independent emission quenching, together leading to the long-range QF sensitivity toward multiple VOCs.