Coordination Environment Regulation of Cucurbit[6]uril-Based Metal–Organic Rotaxane Networks for Proton Conduction
Yanjun Xu, Ying Li, Junjun Li, Zhen-Jie Feng, Xinlong Wang, Mingyue Fan, Xue-Song Wu, Jing Sun, Kui‐Zhan Shao, Zhong‐Min Su
Abstract
Two new cucurbit[6]uril-based metal–organic rotaxane networks (MORNs), [Zn2(PR44)(BDC)2Cl2]·2DMF and [Zn2(PR44)(BDC)2(FA)2]·2DMF (CUST-703 and CUST-704), have been synthesized via a simple anion modulation strategy under solvothermal conditions. Single-crystal X-ray diffraction shows that the chlorine anions and formate anions are coordinate with the mononuclear metal zinc cations in CUST-703 and CUST-704, respectively. CUST-703 exhibits a one-dimensional (1D) chain structure, while CUST-704 has a two-dimensional (2D) layered structure. They can be expanded into three-dimensional (3D) supramolecular frameworks through extensive hydrogen bonding and C–H···π interactions. In addition, their proton conduction properties were also investigated in detail. Interestingly, compared with CUST-703, CUST-704 exhibits a one order of magnitude enhancement in proton conductivity, and its proton conductivity can reach 0.59 × 10–3 S cm–1 at 85 °C and 97% relative humidity (RH), which suggests that the formate anions can effectively promote proton transfer.