Zheng Bin, Wang Jinlei, Zhang Li, Wang Lianli
School of Materials Science and Engineering, Xi'an University of Science and Technology, Xi'an 710054, PR China.
Dalton Trans. 2021 Nov 16;50(44):16371-16376. doi: 10.1039/d1dt02538d.
Flexible metal-organic framework (MOF) materials have the ability to perform stimulated sudden volume contractions, and thus attract increasing attention for use in potential applications such as: actuators or sensors. Here, the structural transition of MIL-53(Cr) loaded with a high concentration of CHOH (CHOH) guest molecules, which cause internal pressure due to guest-guest interactions, was investigated. The pressure triggering the structural transition can be enhanced by high guest molecule loadings (1 CHOH per unit cell (UC): 5 MPa, empty: 53 MPa, 7 CHOH per UC: 90 MPa, and 8 CHOH per UC: 280 MPa). The asymmetrical and small distortion of the organic-inorganic connections are the main microscopic characteristic of the structural transition of MIL-53(Cr) with a high CHOH loading. The external pressure and the internal pressure, instead of the adsorption of the guest molecules, became dominant in the structural transition of MIL-53(Cr). Current studies showed that the high-pressure response of the flexible MOF structure may broaden the acceptable pressure range in future actuator or sensor applications.
柔性金属有机框架（MOF）材料具有在刺激下突然发生体积收缩的能力，因此在诸如致动器或传感器等潜在应用中受到越来越多的关注。在此，研究了负载高浓度CHOH（CHOH）客体分子的MIL-53（Cr）的结构转变，这些客体分子由于客体-客体相互作用而产生内部压力。通过高客体分子负载量（每晶胞（UC）1个CHOH：5 MPa，空晶胞：53 MPa，每UC 7个CHOH：90 MPa，每UC 8个CHOH：280 MPa）可增强触发结构转变的压力。有机-无机连接的不对称和小畸变是高CHOH负载量下MIL-53（Cr）结构转变的主要微观特征。在MIL-53（Cr）的结构转变中，外部压力和内部压力而非客体分子的吸附起主导作用。当前研究表明，柔性MOF结构的高压响应可能会拓宽未来致动器或传感器应用中的可接受压力范围。
