Department of Chemistry, University of Nebraska-Lincoln , Lincoln, Nebraska 68588, United States.
Chemical Biology Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences , Magyar tudósok krt. 2, H-1117 Budapest, Hungary.
J Am Chem Soc. 2016 Aug 17;138(32):10293-8. doi: 10.1021/jacs.6b05626. Epub 2016 Aug 4.
We describe a new strategy to generate non-coordinating anions using zwitterionic metal-organic frameworks (MOFs). By assembly of anionic inorganic secondary building blocks (SBUs) (In(CO2)4) with cationic metalloporphyrin-based organic linkers, we prepared zwitterionic MOFs in which the complete internal charge separation effectively prevents the potential binding of the counteranion to the cationic metal center. We demonstrate the enhanced Lewis acidity of Mn(III)- and Fe(III)-porphyrins in the zwitterionic MOFs in three representative electrocyclization reactions: [2 + 1] cycloisomerization of enynes, [3 + 2] cycloaddition of aziridines and alkenes, and [4 + 2] hetero-Diels-Alder cycloaddition of aldehydes with dienes. This work paves a new way to design functional MOFs for tunable chemical catalysis.
我们描述了一种使用两性离子金属有机骨架（MOFs）生成非配位阴离子的新策略。通过阴离子无机次级建筑块(In(CO2)4)与阳离子金属卟啉基有机连接体的组装，我们制备了两性离子 MOFs，其中完全的内部电荷分离有效地阻止了抗衡阴离子与阳离子金属中心的潜在结合。我们在三个代表性的电环化反应中证明了 Mn(III)-和 Fe(III)-卟啉在两性离子 MOFs 中的增强路易斯酸度：烯炔的[2 + 1]环异构化反应、氮丙啶和烯烃的[3 + 2]环加成反应以及醛与二烯的[4 + 2]杂-Diels-Alder 环加成反应。这项工作为可调谐化学催化的功能 MOFs 的设计开辟了一条新途径。
