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Effect of the Counterion on Light Emission: A Displacement Strategy to Change the Emission Behaviour from Aggregation-Caused Quenching to Aggregation-Induced Emission and to Construct Sensitive Fluorescent Sensors for Hg2+ Detection

Authors

  • Dr. Na Zhao,

    1. HKUST-Shenzhen Research Institute, No. 9 Yuexing 1st RD, South Area, Hi-tech Park, Nanshan, Shenzhen, 518057 (P.R. China), Fax: (+852) 2358-1594
    2. Department of Chemistry, Division of Biomedical Engineering, Institute for Advanced Study and Institute of Molecular, Functional Materials, The Hong Kong University of Science & Technology (HKUST), Clear Water Bay, Kowloon, Hong Kong (P.R. China)
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  • Dr. Jacky W. Y. Lam,

    1. HKUST-Shenzhen Research Institute, No. 9 Yuexing 1st RD, South Area, Hi-tech Park, Nanshan, Shenzhen, 518057 (P.R. China), Fax: (+852) 2358-1594
    2. Department of Chemistry, Division of Biomedical Engineering, Institute for Advanced Study and Institute of Molecular, Functional Materials, The Hong Kong University of Science & Technology (HKUST), Clear Water Bay, Kowloon, Hong Kong (P.R. China)
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  • Dr. Herman H. Y. Sung,

    1. Department of Chemistry, Division of Biomedical Engineering, Institute for Advanced Study and Institute of Molecular, Functional Materials, The Hong Kong University of Science & Technology (HKUST), Clear Water Bay, Kowloon, Hong Kong (P.R. China)
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  • Dr. Hui Min Su,

    1. Department of Physics, HKUST, Clear Water Bay, Kowloon, Hong Kong (P.R. China)
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  • Prof. Ian D. Williams,

    1. Department of Chemistry, Division of Biomedical Engineering, Institute for Advanced Study and Institute of Molecular, Functional Materials, The Hong Kong University of Science & Technology (HKUST), Clear Water Bay, Kowloon, Hong Kong (P.R. China)
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  • Prof. Kam Sing Wong,

    1. Department of Physics, HKUST, Clear Water Bay, Kowloon, Hong Kong (P.R. China)
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  • Prof. Ben Zhong Tang

    Corresponding author
    1. HKUST-Shenzhen Research Institute, No. 9 Yuexing 1st RD, South Area, Hi-tech Park, Nanshan, Shenzhen, 518057 (P.R. China), Fax: (+852) 2358-1594
    2. Department of Chemistry, Division of Biomedical Engineering, Institute for Advanced Study and Institute of Molecular, Functional Materials, The Hong Kong University of Science & Technology (HKUST), Clear Water Bay, Kowloon, Hong Kong (P.R. China)
    3. Guangdong Innovative Research Team, SCUT-HKUST Joint Research Laboratory, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640 (P.R. China)
    • HKUST-Shenzhen Research Institute, No. 9 Yuexing 1st RD, South Area, Hi-tech Park, Nanshan, Shenzhen, 518057 (P.R. China), Fax: (+852) 2358-1594

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Abstract

In this paper, a simple strategy to change the emission behaviour of luminogenic materials was developed. Tetraphenylethene (TPE)-functionalised benzothiazolium salts with different counteranions (TPEBe[BOND]X; X=I, ClO4 and PF6) were designed and synthesised. All the luminogens show weak red emission in the solution state that originates from intramolecular charge transfer from TPE to the benzothiazolium unit. Whereas aggregate formation enhances the light emission of TPEBe[BOND]ClO4 and TPEBe[BOND]PF6, that of TPEBe[BOND]I is quenched, thus demonstrating the phenomena of aggregation-induced emission and aggregation-caused quenching. TPEBe[BOND]I works as a light-up fluorescent sensor for Hg2+ in aqueous solution with high sensitivity and specificity owing to the elimination of the emission quenching effect of the iodide ion by the formation of HgI2 as well as the induction in aggregate formation by the complexation of Hg2+ with the S atom of the benzothiazolium unit of TPEBe[BOND]I. A solid film of TPEBe[BOND]I was prepared that can monitor the level of Hg2+ in aqueous solution with a detection limit of 1 μM.

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