In a film-based fluorescence sensor, luminogens are of vital importance since they play the role of probes or indicators. Traditional organic luminogens like pyrene show high luminescence quantum yields in dilute solutions, but their applications are usually limited by the aggregation-caused quenching (ACQ) effect and bad photochemical stability. Thus, this paper reports a novel aggregation-induced emission luminogen (AIEgen) containing both pyrene and o-carborane (CB-PY), which possesses unique dual-phase emission both in solution and solid state and intramolecular charge transfer (ICT) properties, fulfilling the gap between ACQ and AIE compounds. Importantly, the fluorophore presents extraordinary stability that there was almost no attenuation in the emission intensity of CB-PY in the solid state after 4 months of exposure at ambient conditions. It is these merits that make CB-PY exhibit outstanding sensing performances for volatile organic compounds (VOCs), where the fluorescence test strip shows fast, reversible, and visual discrimination of four organic solvents with varied polarities. Moreover, 92#, 95#, and 98# gasolines could be discriminated with CB-PY, showing different colors under UV illumination.

Among them, fluorescent sensors have attracted most attention of scientists due to their outstanding advantages, such as high sensitivity, low cost, excellent selectivity, ease of sensor preparation, etc. [4][5][6][7][8] In the sensing process, the first excited electronic state of a luminogen presents high sensibility to surrounding microenvironments including temperature, pressure, relative humidity (RH), and solvent polarity, thus the luminogens are of great significance. [9][10][11][12][13][14] Rylene diimides (RDIs), as one of the most important families of dye molecules, have been extensively studied due to their electron-accepting capacity and conducting properties. [15,16] There are various classes of RDIs, such as pyromellitic diimide (PMI), [17] 1,4,5,8-naphthalenediimide (NDI), [18] pyrene diimide (PYI), [19] perylene tetracarboxylic diimide (PDI), [20] and other larger diimides. [21] Among them, PMIs with an aromatic ring in the center and the tetracarboxylic diimides on the sides of the ring have drawn much attention. [22] PMI derivatives could be easily synthesized through a single-step reaction of the pyromellitic dianhydride and the amines, which facilitates the large-scale preparation owing to the high conversion yield and ease of purification procedures. [23] Nevertheless, However, due to the low fluorescence quantum yield and poor photostability of PMI derivatives, much fewer attempts have been made to fabricate fluorescence sensors based on PMI derivatives compared with NDI and PDI derivatives. Thus, it is still challenging to design and synthesize PMI-based luminogens that exhibit excellent photophysical characteristics, such as high luminescence, photostability, and high response specificity, for their applications in fluorescent sensors.In this work, we design and synthesize o-carborane modified pyromellitic diimide derivative (CB-PMI) fluorescent materials with enhanced amine-response, which offers the possibility for real-time and visual detection of lung cancer. A representative molecule CB-PMI consists of a PMI core, two phenyl rings (π-bridge), and two o-carborane units (Scheme 1). The o-carborane moieties with 3D topology are introduced to enhance the photostability and modulate the molecular energy gap of the PMI derivative. [24][25][26] Photophysical properties of as-synthesized CB-PMI both in the solution and solid states were carefully investigated. Subsequently, the sensing performance of CB-PMI Aniline is an important biomarker in human exhaled breath for lung cancer, thus aniline sensing is of paramount importance. However, highly sensitive and selective detection of aniline in high moisture environment of exhaled breath is still challenging. In this work, a new fluorescence sensor for aniline with ultrahigh sensitivity is constructed. The o-carborane modified pyromellitic diimide derivative (CB-PMI) is designed and prepared as the sensitive layer for the fluorescence sensor. As-prepared sensing films exhibit a highly improved response toward aniline vapor. The good sensing per...

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