Supramolecular Polymer Hydrogels from Bolaamphiphilic L-Histidine and Benzene Dicarboxylic Acids: Thixotropy and Significant Enhancement of EuIII Fluorescence

Authors

  • Yaqing Liu,

    1. Beijing National Laboratory for Molecular Science, CAS Key Laboratory of Colloid, Interface and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Science, Beijing 100190 (China), Fax: (+86) 10-6256-9564
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  • Dr. Tianyu Wang,

    Corresponding author
    1. Beijing National Laboratory for Molecular Science, CAS Key Laboratory of Colloid, Interface and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Science, Beijing 100190 (China), Fax: (+86) 10-6256-9564
    • Beijing National Laboratory for Molecular Science, CAS Key Laboratory of Colloid, Interface and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Science, Beijing 100190 (China), Fax: (+86) 10-6256-9564
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  • Prof. Dr. Minghua Liu

    Corresponding author
    1. Beijing National Laboratory for Molecular Science, CAS Key Laboratory of Colloid, Interface and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Science, Beijing 100190 (China), Fax: (+86) 10-6256-9564
    • Beijing National Laboratory for Molecular Science, CAS Key Laboratory of Colloid, Interface and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Science, Beijing 100190 (China), Fax: (+86) 10-6256-9564
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Abstract

Supramolecular polymers from the bolaamphiphilic L-histidine (BolaHis) and benzene dicarboxylic acids (o-phthalic acid, OPA; isophthalic acid, IPA and terephthalic acid, TPA) were found to form hydrogels although neither of the single components could gel water. It was suggested that the hydrogen bond and ionic interactions among different imidazole and carboxylic acid groups are responsible for the formation of the supramolecular polymer as well as the hydrogel formation. Depending on the structures of the dicarboxylic acids, different behaviors of the gels were observed. The hydrogels from OPA/BolaHis and IPA/BolaHis showed thixotropic properties, that is, the hydrogel was destroyed by hand shaking and then slowly gelated again at room temperature. However, the hydrogels of TPA/BolaHis could not. Interestingly, when EuIII was doped into IPA/BolaHis supramolecular polymers, very strong luminescence enhancement was observed. FT-IR spectroscopies and XRD analysis revealed that the strong luminescence enhancement could be attributed to the matched supramolecular nanostructures, which render the correct binding and a good dispersion of EuIII ions. The work offers a new approach for fabricating functional hydrogels through the supramolecular polymers.

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