Reversible Ion-Conducting Switch in a Novel Single-Ion Supramolecular Hydrogel Enabled by Photoresponsive Host-Guest Molecular Recognition

Hu Wang; Chao Nan Zhu; Hong Zeng; Xiaofan Ji; Tao Xie; Xuzhou Yan; Zi Liang Wu; Feihe Huang

doi:10.1002/adma.201807328

Reversible Ion-Conducting Switch in a Novel Single-Ion Supramolecular Hydrogel Enabled by Photoresponsive Host-Guest Molecular Recognition

Adv Mater. 2019 Mar;31(12):e1807328. doi: 10.1002/adma.201807328. Epub 2019 Jan 29.

Authors

Hu Wang¹, Chao Nan Zhu², Hong Zeng¹, Xiaofan Ji³, Tao Xie⁴, Xuzhou Yan⁵, Zi Liang Wu², Feihe Huang¹

Affiliations

¹ State Key Laboratory of Chemical Engineering, Center for Chemistry of High-Performance and Novel Materials, Department of Chemistry, Zhejiang University, Hangzhou, 310027, P. R. China.
² Ministry of Education Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou, 310027, P. R. China.
³ Department of Chemistry, The University of Texas at Austin, 105 East 24th Street, Stop A5300, AustinTX, 78712, USA.
⁴ State Key Laboratory of Chemical Engineering, College of Chemical and Biological Engineering, Zhejiang University, 38 Zheda Road, Hangzhou, 310027, P. R. China.
⁵ School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China.

PMID: 30694589
DOI: 10.1002/adma.201807328

Abstract

A novel ion-conducting supramolecular hydrogel with reversible photoconductive properties in which the azobenzene motif, α-cyclodextrin (α-CD), and ionic liquid are grafted onto the gel matrix is reported. Host-guest interactions with different association constants between α-CD and azobenzene or the anionic part of the ionic liquid can be readily tuned by photoinduced trans-cis isomerization of the azobenzene unit. When irradiated by 365 nm light, α-CD prefers to form a complex with the anionic part of the ionic liquid, resulting in decreased ionic mobility and thus high resistance of the hydrogel. However, under 420 nm light irradiation, a more stable complex is again formed between α-CD and trans-azobenzene, thereby releasing the bound anions to regenerate the low-resistive hydrogel. As such, remote control of the ionic conductivity of the hydrogel is realized by simple host-guest chemistry. With the incorporation of a logic gate, this hydrogel is able to reversibly switch an electric circuit on and off by light irradiation with certain wavelengths. The concept of photoswitchable ionic conductivity of a hydrogel mediated by competitive molecular recognition is potentially promising toward the fabrication of optoelectronic devices and applications in bioelectronic technology.

Keywords: host-guest interactions; hydrogel; photoconductive effect; photoresponsiveness; supramolecular chemistry.

Abstract

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