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.
Ministry of Education Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou, 310027, P. R. China.
Adv Mater. 2019 Mar;31(12):e1807328. doi: 10.1002/adma.201807328. Epub 2019 Jan 29.
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.
本文报道了一种新型离子导电超分子水凝胶，其中接枝到凝胶基质上的是偶氮苯结构、α-环糊精（α-CD）和离子液体。通过偶氮苯单元的光致顺反异构化，α-CD 与偶氮苯或离子液体的阴离子部分之间的不同结合常数的主客体相互作用可以很容易地进行调节。当用 365nm 光照射时，α-CD 更倾向于与离子液体的阴离子部分形成复合物，从而降低离子迁移率，从而使水凝胶呈现高电阻。然而，在 420nm 光照射下，α-CD 与反式偶氮苯之间再次形成更稳定的复合物，从而释放结合的阴离子，再生低电阻水凝胶。通过简单的主客体化学，可以实现对水凝胶离子电导率的远程控制。通过用特定波长的光照射，将逻辑门纳入其中，这种水凝胶可以可逆地打开和关闭电路。这种由竞争分子识别介导的水凝胶的光致离子电导率开关的概念，有望用于制造光电设备和生物电子技术中的应用。
