Park Seonghun, Lee Juhyung, Kim Bongkyeom, Jung Chan-Yong, Bae Sang-Eun, Kang Joongoo, Moon Dohyun, Park Jinhee
Department of Physics and Chemistry, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, Republic of Korea.
Nuclear Chemistry Technology Division, Korea Atomic Energy Research Institute, Daejeon 34057, Republic of Korea.
J Am Chem Soc. 2024 Apr 3;146(13):9293-9301. doi: 10.1021/jacs.4c01040. Epub 2024 Mar 22.
Self-assembly-based structural transition has been explored for various applications, including molecular machines, sensors, and drug delivery. In this study, we developed new redox-active metal-organic frameworks (MOFs) called DGIST-10 series that comprise π-acidic 1,4,5,8-naphthalenediimide (NDI)-based ligands and Ni ions, aiming to boost ligand-self-assembly-driven structural transition and study the involved mechanism. Notably, during the synthesis of the MOFs, a single-crystal-amorphous-single-crystal structural transition occurred within the MOFs upon radical formation, which was ascribed to the fact that radicals prefer spin-pairing or through-space electron delocalization by π-orbital overlap. The radical-formation-induced structural transitions were further confirmed by the postsynthetic solvothermal treatment of isolated nonradical MOF crystals. Notably, the transient amorphous phase without morphological disintegration was clearly observed, contributing to the seminal structural change of the MOF. We believe that this unprecedented structural transition triggered by the ligand self-assembly magnifies the structural flexibility and diversity of MOFs, which is one of the pivotal aspects of MOFs.
基于自组装的结构转变已被用于各种应用，包括分子机器、传感器和药物递送。在本研究中，我们开发了名为DGIST-10系列的新型氧化还原活性金属有机框架（MOF），其由基于π-酸性1,4,5,8-萘二酰亚胺（NDI）的配体和镍离子组成，旨在促进配体自组装驱动的结构转变并研究其中涉及的机制。值得注意的是，在MOF的合成过程中，MOF内部在自由基形成时发生了单晶-非晶-单晶结构转变，这归因于自由基倾向于通过π轨道重叠进行自旋配对或空间电子离域。通过对分离出的非自由基MOF晶体进行合成后溶剂热处理，进一步证实了自由基形成诱导的结构转变。值得注意的是，清晰地观察到了没有形态崩解的瞬态非晶相，这促成了MOF的重大结构变化。我们认为，这种由配体自组装引发的前所未有的结构转变放大了MOF的结构灵活性和多样性，这是MOF的关键特性之一。
