title: Rational Design of a Red-Emissive Fluorophore with AIE and ESIPT Characteristics and Its Application in Light-Up Sensing of Esterase.
abstract: The development of red fluorophores with efficient solid-state emission is still challenging. Herein, a red fluorophore 1 with aggregation-induced emission (AIE) and excited-state intramolecular proton transfer (ESIPT) characteristics is rationally designed and facilely synthesized by attaching an electron-donor diethylamine and an electron-acceptor maleonitrile group to salicyladazine. In contrast to many red fluorophores which undergo serious aggregation-caused quenching (ACQ), compound 1 emits bright red fluorescence (λem= 650 nm, ΦF= 24.3%) in the solid state with a large Stokes shift of 174 nm. Interestingly, control compounds 2 and 3, which have similar structures as 1, exhibit obvious aggregation-caused quenching (ACQ) characteristics. The difference in the crystal structures of 1, 2, and 3 reveals that the interplanar spacing among molecules plays a decisive role in realizing the AIE characteristics of 1. Moreover, when the hydroxyl group of 1 was substituted by an esterase reactive acetoxyl, a fluorescence light-up probe 4 was developed for sensing of esterase based on the selective reaction between 4 and esterase to generate the AIE and ESIPT active molecule 1. The linear range for in vitro quantification of esterase is 0.01-0.15 U/mL with a detection limit of 0.005 U/mL. Probe 4 was also successfully applied to image esterase in mitochondria of living cells.
authors.affiliation: Department of Chemistry, Beijing Key Laboratory for Analytical Methods and Instrumentation, Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology, Tsinghua University , Beijing 100084, People's Republic of China.|Department of Chemical and Biomolecular Engineering, National University of Singapore , 4 Engineering Drive 4, Singapore 117585, Singapore.
authors.forename: Lu
authors.initials: L
authors.lastname: Peng
authors.affiliation: Department of Chemical and Biomolecular Engineering, National University of Singapore , 4 Engineering Drive 4, Singapore 117585, Singapore.
authors.forename: Shidang
authors.initials: S
authors.lastname: Xu
authors.affiliation: Department of Chemistry, Beijing Key Laboratory for Analytical Methods and Instrumentation, Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology, Tsinghua University , Beijing 100084, People's Republic of China.
authors.forename: Xiaokun
authors.initials: X
authors.lastname: Zheng
authors.affiliation: Department of Chemical and Biomolecular Engineering, National University of Singapore , 4 Engineering Drive 4, Singapore 117585, Singapore.
authors.forename: Xiamin
authors.initials: X
authors.lastname: Cheng
authors.affiliation: Department of Chemical and Biomolecular Engineering, National University of Singapore , 4 Engineering Drive 4, Singapore 117585, Singapore.
authors.forename: Ruoyu
authors.identifier: 0000-0002-4086-9566
authors.initials: R
authors.lastname: Zhang
authors.affiliation: Department of Chemical and Biomolecular Engineering, National University of Singapore , 4 Engineering Drive 4, Singapore 117585, Singapore.
authors.forename: Jie
authors.initials: J
authors.lastname: Liu
authors.affiliation: Department of Chemical and Biomolecular Engineering, National University of Singapore , 4 Engineering Drive 4, Singapore 117585, Singapore.|Institute of Materials Research and Engineering (A*STAR) , 3 Research Link, Singapore 117602, Singapore.
authors.forename: Bin
authors.identifier: 0000-0002-0956-2777
authors.initials: B
authors.lastname: Liu
authors.affiliation: Department of Chemistry, Beijing Key Laboratory for Analytical Methods and Instrumentation, Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology, Tsinghua University , Beijing 100084, People's Republic of China.
authors.forename: Aijun
authors.identifier: 0000-0003-0633-4098
authors.initials: A
authors.lastname: Tong
mesh_terms: D004950:Esterases / Q000032:analysis* / Q000378:metabolism; D005456:Fluorescent Dyes / Q000138:chemical synthesis / Q000737:chemistry*; D006367:HeLa Cells; D006801:Humans; D061986:MCF-7 Cells; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000201:enzymology; D011522:Protons; D013050:Spectrometry, Fluorescence
chemical_list: D005456:Fluorescent Dyes; D011522:Protons; D004950:Esterases