Cucurbit[7]uril: A Simple Macrocyclic, pH-Triggered Hydrogelator Exhibiting Guest-Induced Stimuli-Responsive Behavior

Authors

  • Ilha Hwang,

    1. National Creative Research Initiative Center for Smart, Supramolecules and Department of Chemistry, Pohang University of Science and Technology, San 31 Hyoja-dong, Pohang 790-784, Republic of Korea, Fax: (+82) 54-279-8129 http://css.postech.ac.kr
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  • Woo Sung Jeon Dr.,

    1. National Creative Research Initiative Center for Smart, Supramolecules and Department of Chemistry, Pohang University of Science and Technology, San 31 Hyoja-dong, Pohang 790-784, Republic of Korea, Fax: (+82) 54-279-8129 http://css.postech.ac.kr
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  • Hee-Joon Kim Dr.,

    1. National Creative Research Initiative Center for Smart, Supramolecules and Department of Chemistry, Pohang University of Science and Technology, San 31 Hyoja-dong, Pohang 790-784, Republic of Korea, Fax: (+82) 54-279-8129 http://css.postech.ac.kr
    2. Current address: Department of Applied Chemistry, Kumoh National Institute of Technology, 1 Yangho-dong, Gumi 730-701, Republic of Korea
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  • Dongwoo Kim Dr.,

    1. National Creative Research Initiative Center for Smart, Supramolecules and Department of Chemistry, Pohang University of Science and Technology, San 31 Hyoja-dong, Pohang 790-784, Republic of Korea, Fax: (+82) 54-279-8129 http://css.postech.ac.kr
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  • Hyunuk Kim,

    1. National Creative Research Initiative Center for Smart, Supramolecules and Department of Chemistry, Pohang University of Science and Technology, San 31 Hyoja-dong, Pohang 790-784, Republic of Korea, Fax: (+82) 54-279-8129 http://css.postech.ac.kr
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  • Narayanan Selvapalam Dr.,

    1. National Creative Research Initiative Center for Smart, Supramolecules and Department of Chemistry, Pohang University of Science and Technology, San 31 Hyoja-dong, Pohang 790-784, Republic of Korea, Fax: (+82) 54-279-8129 http://css.postech.ac.kr
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  • Norifumi Fujita Dr.,

    1. Department of Chemistry & Biochemistry, Graduated School of Engineering, Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395, Japan
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  • Seiji Shinkai Prof. Dr.,

    1. Department of Chemistry & Biochemistry, Graduated School of Engineering, Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395, Japan
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  • Kimoon Kim Prof. Dr.

    1. National Creative Research Initiative Center for Smart, Supramolecules and Department of Chemistry, Pohang University of Science and Technology, San 31 Hyoja-dong, Pohang 790-784, Republic of Korea, Fax: (+82) 54-279-8129 http://css.postech.ac.kr
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  • We gratefully acknowledge the Creative Research Initiatives and BK 21 programs for support of this work. We also thank Prof. W.-C. Zin for helpful discussions and Prof. Jaheon Kim for helping us solve the X-ray crystal structure. The X-ray diffraction measurements were performed at the Pohang Accelerator Laboratory (Beamlines 3C2, 4C1, and 4A).

Abstract

original image

Without modification of its periphery, cucurbit[7]uril (a macrocyclic cavitand comprising seven glycoluril units) forms a hydrogel. The gelation is thermoreversible and sensitive to pH, but is inhibited by the presence of alkali-metal ions and shows guest-induced stimuli-responsive behavior: upon addition of a small amount of a guest, it undergoes a reversible gel–sol transition with alternating UV irradiation and heat treatment (see picture).

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