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Bacterial infection poses great threats to human health and the emergence of drug-resistant bacteria requires effective methods to eliminate bacteria and avoid bacterial resistant. Photodynamic therapy (PDT), which applies photosensitizers (PSs) to generate reactive oxygen species (ROS) under light irradiation, has attracted widespread concern on bacterial treatment, recently. In this work, we develop a far red/near-infrared (FR/NIR)-emissive fluorescent molecule, AIE-TEA, with aggregation-induced emission (AIE) characteristics, for FR/NIR imaging and PDT of bacteria. Due to AIE characteristics and a certain degree of water dispersity, the AIE-TEA can conduct imaging of bacteria without wash process. Moreover, the AIE-TEA can effectively generate ROS under ultralow power white light irradiation (20 mW cm−2) with quantum yield of up to 83%, which is crucial for PDT of bacteria. The AIE-TEA can selectively kill Gram-positive bacteria (S. aureus) via image-guided PDT.

Mechanofluorochromic (MFC) materials display a photoluminescence color change in response to mechanical grinding and pressing. Development of an effective molecular design strategy to tune MFC activity is still challenging. Herein, seven 9, 10-distyrylanthracene (DSA)-based molecules are designed and synthesized as promising MFC materials. These molecules adopt a five-plane twisted spatial conformation that are composed of an anthryl ring and four phenyl rings. The inclusion of cyano groups and different substituents in this five-plane system causes some changes in the intramolecular charge transfer (ICT) and molecular conformation, which can directly induce new MFC activities. Among seven DSA derivatives, DSA-CN5 exhibits the highest MFC activity upon grinding. Based on the good sensitivity and repeatability of MFC process as well as suitable stability of the ground state, DSA-CN5 is selected to fabricate the rewritable papers and can be achieved in inkless printing technologies.

Biogenic amines are generally produced from the degradation of amino acids in biometabolism, which can be used as an important biomarker for food spoilage. Rapid, simple and accurate detection of biogenic amines is an important task for the food safety. Here we synthesize a series of coumarin hydrozone derivatives with high solid-state emission. BDCH2 exhibits a fluorescent switch between the yellow emission (λem,max = 555 nm) and the NIR region (λem,max = 720 nm) upon HCl/NH3 vapor stimuli. The response time for NH3 vapor is only 2 s. Utilizing this property, BDCH2 as a biogenic amine vapors sensor can be readily applied in the detection of food spoilage for real-time and visual monitoring the freshness of crawfish and fish with quick response, easy visualization and simple operation.

A tetraphenylethene (TPE) derivative tetra(3-1 H -benzo[ d ]imidazol-2-yl) -4-hydroxyphenyl)ethene (TBIHPE) which exhibits crystallization-induced emission enhancement (CIEE) induced by tetrahydrofuran (THF) and reversible fluorescence shifting upon HCl fuming and heating or NH 3 fuming was prepared. The CIEE and reversible fluorescence shift process were controlled by imino group and tertiary amine group of 2-(2′-Hydroxyphenyl)benzimidazole (HBI) moiety, respectively. The intermolecular hydrogen bonds between THF and imino group have been observed by single-crystal X-ray structural analysis, which changed the excited-state intramolecular proton transfer (ESIPT) process of TBIHPE, and induced the CIEE phenomena. The fluorescence emission peak of TBIHPE shows blue shift upon HCl fuming stimuli in solid state. Moreover, the fluorescence emission of HCl fumed TBIHPE solid can recover by heating or fuming in NH 3 vapors. Based on the results, the relationship between photophysical properties and protonation-deprotonation stimuli was discussed.

A single chain synthetic amphiphile, 4-(2-hexadecyloxynaphthalene-6-oxy)butyl trimethylammonium bromide (C16Naph(2,6)C4N+), can self-assemble into vesicles in the dilute solution. The fluorescence resonance energy transfer has been studied in aqueous vesicle solution of C12Naph(1,5)C4N+ and hydrophilic dye fluorescein sodium salt (FS). The donor, naphthalene group, was embedded in the interior of the vesicles. The acceptor, FS with two negatively charged polar groups, was bound electrostatically to the positively charged surface of (C16Naph(2,6)C4N+) vesicles. The FS quenched the fluorescence intensity of the naphthalene, which fitted a Stern–Volmer plot, and the Stern–Volmer quenching-constant Ksv is 5.65 × 105 mol−1. The energy transfer efficiency increased with the increasing concentration of FS acceptor in the range of 0–4.4 × 10−6 dm3 mol−1 up to ca. 71% which could be ascribed to the ordered arrangement of chromophores inside the vesicles.

A single chain synthetic amphiphile, 4-(5-dodecyloxynaphthalene-1-oxy) butyl trimethylammonium bromide (C 12 Naph(1,5)C 4 N + ), can be self-assembled into vesicles in the dilute aqueous solution and subsequently form excimer in the vesicles. The excitation energy transfer has been performed in the C 12 Naph(1,5)C 4 N + aqueous vesicles. The donor, naphthalene group, was embedded in the interior of the vesicles. The acceptor, titan yellow, with two negatively charged polar groups, was bound electrostatically to the positively charged surface of vesicles. The energy transfer efficiency increased with the increase of the concentration of titan yellow acceptor in the range of 0–1.2 × 10 −5 mol dm −3 . Titan yellow quenched the fluorescence intensity of the naphthalene, which fitted a Stern–Volmer plot, and the Stern–Volmer quenching constant K sv is 1.75 × 10 4 dm 3 mol −1 .