조회 . 351 
 등록 일 . 2019 . 06 . 25 
 A molecule - trapping material that normally degrades in water remains stable after two years of humidity exposure when treated with a common skin bleach . 
 △ Professor Nak Cheon Jeong ( right back ) and his team at DGIST collaborated with researchers in Korea to find ways to stabilize HKUST - 1 in water . 
 Adding hydroquinone , a skin - bleaching ingredient , to a well - known ‘ metal organic framework ’ changes its copper ions in a way that makes this porous material exceptionally stable in water . 
 “ We developed a new method to enhance the water stability of metal organic frameworks , with potential for applications that can effectively filter and purify air from ultrafine dust without decomposing due to humidity , ” says DGIST materials scientist Nak Cheon Jeong . The Korean researchers reported their findings in the Journal of the American Chemical Society . 
 Metal organic frameworks ( MOFs ) are made from metal ions bonded by organic links . They assemble in a way that leads to the formation of internal cage - like structures , giving the material its porous nature . MOFs have an impressive surface area compared to other porous materials . It is this , and the ability of scientists to tune their structures , that has led to their use in a wide range of applications , including gas uptake , molecule separation , drug delivery , and catalysis . Most MOFs decompose in the presence of humidity and water , so scientists have been looking for ways to make them more durable . 
 Jeong and his colleagues found that treating a well - known copper - based MOF , called HKUST - 1 , with hydroquinone at 80 ° C made the material so stable that it didn ’ t degrade after weeks of submersion in water or even after two years of exposure to humid air . 
 Copper ions and their organic links in HKUST - 1 assemble to form large and small cages with paddlewheel - shaped metal ion nodes . Normally , water molecules attach to elements within this MOF , displacing the bonds between the copper ions and organic links , and causing the material to degrade or transform into a non - porous solid . Hydroquinone treatment , on the other hand , leads to a very stable HKUST - 1 in water . 
 Jeong and his team found that a single electron from hydroquinone is transferred to cupric ions ( Cu 2 +) within HKUST - 1 , changing them to cuprous ions ( Cu +). This change is self - limiting : no more than 30 % of the cupric ions change in this way . Half of the Cu + ions remain in their positions on HKUST - 1 ’ s paddlewheel cages . But the other half form complexes that dissociate from the structure and become trapped within the material ’ s smaller cages , like a ship - in - a - bottle . 
 Further studies are needed to understand exactly how these changes lead to such a substantial improvement in HKUST - 1 ’ s stability in water . 
 Jeong and his team believe the same concept could be applied to other copper - based paddlewheel MOFs . They plan to conduct follow - up research on potential practical applications for their approach . 
 Nak Cheon Jeong , Associate Professor 
 Department of Emerging Materials Science 
 E - mail : nc @ dgist . ac . kr 
 Research Paper on Journal of American Chemical Society 
 https : / / pubs . acs . org / doi / abs / 10 . 1021 / jacs . 9 b 02114 
 Dahae Song , Jinhee Bae , Hoon Ji , Min - Bum Kim , Youn - Sang Bae , Kyo Sung Park , Dohyun Moon , and Nak Cheon Jeong , " Coordinative Reduction of Metal Nodes Enhances the Hydrolytic Stability of a Paddlewheel Metal − Organic Framework ", JACS , offline - published on May 2019 / JACS , online - published on April 5 th , 2019 
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