Isotope-selective responsive system based on molecular recognition in porous materials has potential for the storage and purification of isotopic mixtures but is considered unachievable because of the almost identical physicochemical properties of the isotopes. Herein, a unique isotope-responsive breathing transition of the flexible metal-organic framework (MOF), MIL-53(Al), which can selectively recog-nize and respond to only D2 molecules through a secondary breathing transition, is reported. This novel phenomenon is examined using in-situ neutron diffraction experiments un-der same conditions for H2 and D2 sorption experiments. This work can guide the development of a novel isotope-selective recognizing system and provide opportunities to fabricate flexible MOF systems for energy-efficient purification of the isotopic mixture.

中文翻译：

---

柔性金属有机框架中的特定同位素响应呼吸转变

基于多孔材料中分子识别的同位素选择性响应系统具有储存和纯化同位素混合物的潜力，但由于同位素的物理化学性质几乎相同，因此被认为无法实现。本文报道了一种独特的柔性金属有机框架 (MOF) MIL-53(Al) 的同位素响应呼吸转变，它可以通过二次呼吸转变选择性地识别和响应 D2 分子。在与 H2 和 D2 吸附实验相同的条件下，使用原位中子衍射实验来检查这种新现象。这项工作可以指导新型同位素选择性识别系统的开发，并为制造灵活的 MOF 系统以高效纯化同位素混合物提供机会。