High-Performance NMHC Detection Enabled by a Perylene Bisimide-Cored Metallacycle Complex-Based Fluorescent Film Sensor

Non-methane hydrocarbons (NMHCs) can serve as precursors of ozone and photochemical smog, and hence their highly efficient detection is of great importance for air quality monitoring. Here, we synthesized a new fluorescent perylene bisimide (PBI)-cored metallacycle complex through coordination-driven self-assembly and used it for the production of a fluorescent film sensor. The unique rectangular structure of the developed fluorophore endows the sensor with enhanced sensing performance and discriminability to n-alkanes (C_5-10). Specifically, the experimental detection limits for n-pentane, n-hexane, and n-decane are 39, 7, and 1.4 mg/m³, respectively, and the corresponding linear ranges are from 39 to 2546, 7 to 1745, and 1.4 to 85 mg/m³, respectively. Moreover, the sensing is fully reversible. In tandem with a gas chromatographic separation system, the film sensor showed comparable detection ability for the n-alkanes with a commercial flame ionization detector (FID), while the film sensor needs no hydrogen; it occupies a much smaller size (30 × 30 × 44 mm³) and consumes less energy (0.215 W). Further studies demonstrated that the developed sensor can be used for on-site and real-time quantification of NHMCs, laying the foundation for developing into a portable detector.

An O-Carborane Derivative of Perylene Bisimide-Based Thin Film Displaying both Electrochromic and Electrofluorochromic Properties

The widespread application in displays, information encryption, and sensors has boosted studies of electrochromic (EC) systems combining large contrast, fast response, high robustness, and low-cost properties. Herein, we report a film-type new EC system with a non-planar perylene bisimide-carborane derivative (PBI-CB) as the electroactive materials. It was revealed that the film demonstrated outstanding EC properties with response times of 1.18 and 0.94 s for the coloration and bleaching processes, respectively, large transmittance variation around 630 nm (45.7%), and superior stability for more than 200 coloration-bleaching cycles. Moreover, the film also showed precious electrofluorochromic (EFC) properties. The emission around 650 nm at the "on" state could be more than 24.5 times than that at the "off" state, and the response times of the off and on processes could reach 2.2 s and 4.3 s, respectively. Considering the facts that the film was fabricated via simple drop-coating, the EC/EFC operation was performed via a routine three-electrode system and the voltage applied is only -1.3 V, we believe that the EC/EFC system as developed would find applications in smart windows, information encryption, optoelectrical sensing, etc. In addition, the work could also pave the way for developing combined EC/EFC systems via employing known organic fluorophores as the electrochemical active materials, which are not only abundant in numbers but also solution-processable.