Lee Byeongchan, Chen Ying-Pin, Park Jinkyu, Park Jinhee
Department of Emerging Materials Science , Daegu Gyeongbuk Institute of Science and Technology (DGIST) , 333 Techno Jungang-daero , Dalseong-gun, Daegu 42988 , Korea.
Department of Protein Purification , Applied Viromics , Fremont , California 94539 , United States.
ACS Appl Mater Interfaces. 2019 Jul 24;11(29):25817-25823. doi: 10.1021/acsami.9b04768. Epub 2019 Jul 9.
The ability to chemisorb iodine is important for the safe long-term storage of fission products from nuclear reactors. Herein, we successfully used single-crystal X-ray diffraction analysis to crystallographically visualize I binding sites in two isostructural metal-organic frameworks, viz. Co(-DOBDC) (-DOBDC = 4,6-dioxo-1,3-benzenedicarboxylate) and Co(-DOBDC) (-DOBDC = 2,5-dioxo-1,4-benzenedicarboxylate), with increasing I loading. Interestingly, the C-H bond at the electron-rich carbon (C5) of -DOBDC is activated toward electrophilic aromatic substitution, forming an aryl C-I bond and I or I that coordinates to unsaturated open Co sites. Cooperation between the ligand and the open Co sites leads to rapid chemisorption of I even under mild adsorption conditions, such as room temperature. In contrast, molecular I coordinates to the open Co sites of Co(-DOBDC). Owing to the chemisorption of I, I@Co(-DOBDC) decomposes at a much higher temperature than I@Co(-DOBDC), as revealed by thermogravimetric analysis.
对碘进行化学吸附的能力对于核反应堆裂变产物的安全长期储存至关重要。在此，我们成功地利用单晶X射线衍射分析，通过晶体学方法可视化了两种同构金属有机框架（即Co(-DOBDC) （-DOBDC = 4,6-二氧代-1,3-苯二甲酸酯）和Co(-DOBDC) （-DOBDC = 2,5-二氧代-1,4-苯二甲酸酯））中随着碘负载量增加的碘结合位点。有趣的是，-DOBDC富电子碳（C5）处的C-H键朝着亲电芳香取代方向被激活，形成芳基C-I键以及与不饱和开放钴位点配位的I或I。配体与开放钴位点之间的协同作用导致即使在温和的吸附条件下（如室温）碘也能快速化学吸附。相比之下，分子碘与Co(-DOBDC)的开放钴位点配位。热重分析表明，由于碘的化学吸附作用，I@Co(-DOBDC)比I@Co(-DOBDC)在更高的温度下分解。
