Zhang Die, Fu Boyang, He Weilong, Li Hengtao, Liu Fuyang, Wang Luhong, Liu Haozhe, Zhou Liujiang, Cai Weizhao
School of Materials and Energy, University of Electronic Science and Technology of China, Chengdu, 611731, Sichuan, China.
School of Physics, State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 611731, Sichuan, China.
Nat Commun. 2024 Aug 6;15(1):6678. doi: 10.1038/s41467-024-50961-2.
Dynamic crystals with directional deformations in response to external stimuli through molecular reconfiguration, are observed predominantly in certain organic crystals and metal complexes. Low-dimensional hybrid halides, resemble these materials due to the presence of strong hydrogen bonds between bulky organic moieties and inorganic units, whereas their dynamic behavior remains largely unexplored. Here we show that a one-dimensional hybrid halide (MV)BiBr (MV = methylviologen) undergoes an isosymmetric phase transition at hydrostatic pressure of 0.20 GPa, accompanied by a remarkable length expansion of 20-30% and red to dark yellow color change. Unexpectedly, the backward transition can be fully reversed by mechanical stimulation rather than decompression. In the high-pressure phase, the coexistence of strong Bi lone pair stereochemical activity and large reorientations of the planar MV cations, together with the newly formed CH···Br hydrogen interactions, are the structural features that facilitate microscopic changes and stabilize the metastable high-pressure phase at ambient conditions.
通过分子重排响应外部刺激而发生定向变形的动态晶体，主要在某些有机晶体和金属配合物中观察到。低维混合卤化物，由于其庞大的有机部分和无机单元之间存在强氢键，类似于这些材料，然而它们的动态行为在很大程度上仍未被探索。在此，我们表明一维混合卤化物（MV）BiBr（MV = 甲基紫精）在0.20 GPa的静水压力下经历等对称相变，伴随着20 - 30%的显著长度膨胀以及从红色到深黄色的颜色变化。出乎意料的是，向后的转变可以通过机械刺激而非减压完全逆转。在高压相中，Bi孤对电子的强立体化学活性与平面MV阳离子的大角度重排共存，以及新形成的CH···Br氢键相互作用，是促进微观变化并在环境条件下稳定亚稳态高压相的结构特征。
