Highly Porous, Homochiral Metal-Organic Frameworks: Solvent-Exchange-Induced Single-Crystal to Single-Crystal Transformations

摘要

Porous metal-organic frameworks (MOFs) have recently received much attention owing to their potential applications in several technological areas such as gas storage, separation, and heterogeneous catalysis. The modular nature of MOFs means they are readily tunable and, as a result, the synthesis of ideal, heterogenized single-site catalysts can be envisioned from porous MOFs by a judicious choice of metal-connecting nodes and/or bridging ligands. Homochiral, porous MOFs are particularly attractive candidates as heterogeneous asymmetric catalysts for the economical production of optically active organic compounds due to the lack of chiral, inorganic zeolites. Although we and others have recently provided preliminary evidence for the potential utility of homochiral, porous MOFs in enantioselective separation and catalysis, several key issues remain to be addressed before practical applications of such materials can be realized. First, homochiral MOFs with permanent porosity are still extremely rare, even though there are now numerous reported examples of porous, achiral MOFs with extremely high surface areas. Second, as yet there has been no study on the structural integrity of homochiral MOFs under catalytic conditions. Herein we report the design and synthesis of highly porous, homochiral solids based on 1D MOFs and their single-crystal to single-crystal transformations induced by solvent exchange. Our results suggest that the framework integrity of porous, homochiral MOFs can be maintained under typical asymmetric catalytic reaction conditions.