Liu Yidong, Jiang Yunzhe, Heinke Lars
Institute of Functional Interfaces (IFG), Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany.
Langmuir. 2024 Jan 9;40(1):474-479. doi: 10.1021/acs.langmuir.3c02734. Epub 2023 Dec 27.
Photoresponsive materials enable dynamic remote control of their fundamental properties. The incorporation of photochromic molecules in nanoporous metal-organic frameworks (MOFs) provides a unique opportunity to tailor the material properties, including the interaction between the MOF host and guest molecules in the pores. Here, a MOF film of type HKUST-1 with embedded hexaarylbiimidazole (HABI), undergoing reversible light-induced reactions between the stable dimer state and the metastable radical state, is presented. The switching between the dimer and radical form is shown by infrared, UV-vis, and electron paramagnetic resonance (EPR) spectroscopy. By transient uptake experiments with ethanol and methanol as probe molecules, we show that the dimer-radical switching impacts the host-guest interaction and, in particular, modifies the uptake amount and diffusion coefficient of the guest molecules. For ethanol, the diffusion slows down by 75%. This research presents the first MOF material with photoswitchable (meta)stable dimer and radical molecules, and it contributes to the advancement of photoresponsive nanoporous materials.
光响应材料能够对其基本特性进行动态远程控制。在纳米多孔金属有机框架（MOF）中引入光致变色分子为调整材料特性提供了独特的契机，其中包括MOF主体与孔道中客体分子之间的相互作用。在此，本文展示了一种嵌入六芳基双咪唑（HABI）的HKUST-1型MOF薄膜，其在稳定二聚体状态和亚稳态自由基状态之间经历可逆的光诱导反应。通过红外光谱、紫外可见光谱和电子顺磁共振（EPR）光谱显示了二聚体和自由基形式之间的转换。通过以乙醇和甲醇作为探针分子的瞬态吸收实验，我们表明二聚体-自由基转换会影响主体-客体相互作用，特别是会改变客体分子的吸收量和扩散系数。对于乙醇，扩散速度减慢了75%。这项研究展示了第一种具有可光开关（亚）稳定二聚体和自由基分子的MOF材料，并有助于推动光响应纳米多孔材料的发展。
