Non-planar boron-oxygen multiple resonance thin-film fluorescent sensor for high-performance vapor phase BTEX detection

BTEX vapors, comprising benzene, toluene, ethylbenzene, ortho-xylene, meta-xylene, and para-xylene, are classified as volatile organic compounds (VOCs) and present a considerable risk to human health. The sensitive, real-time, rapid and room temperature detection and identification of BTEX vapors through vapor sampling continues to pose a significant challenge within the field. In this study, we creatively have integrated boron-oxygen multiple resonance units with ortho-carborane groups to fabricate film-based fluorescent sensors (FFSs) that demonstrates rapid response, excellent selectivity, repeatability, and high sensitivity towards BTEX vapors at room temperature. The response time is as short as 4 s, and the recovery time is less than 80 s, and after conducting the tests more than 30 times, no discernible deterioration was detected. The experimental detection limits are 30.9 ppm, 44.8 ppm, 34.7 ppm, 44.6 ppm, 30.86 ppm and 69.4 ppm, for benzene, toluene, ethylbenzene, ortho-xylene, meta-xylene, and para-xylene, respectively. The exceptional performance of the sensor was attributed to the non-planar configuration and microenvironmental sensitivity of the sensing fluorophore, as it facilitates the formation of micro-channels within the film. We firmly believe that our work not only achieves reversible fluorescence sensing of BTEX vapors, offering vast potential for applications in air quality assessment, industrial environmental monitoring, and the analysis of photoelectronically inactive VOCs, but also underscores that the integration of a non-planar structure with microenvironmentally sensitive groups represents a highly effective strategy for developing advanced fluorescent sensing films with superior performance.