(652f) Enantioselective Catalysts Based on Metal-Organic Framework Supported Nucleotides

Artificial metalloenzymes (ArMs) combine the catalytic properties of metal ions with the molecular recognition capabilities of biological molecules. A class of ArMs relies on the chiral environment created by natural or synthetic DNA, and the DNA’s strong affinity for metal ions or metal ion complexes to create enantioselective catalytic sites. DNA-based ArMs have been used for the Diels-Alder reaction, Friedel-Crafts alkylation, Michael addition and other reactions. Efforts to develop ArMs with minimal sequences, recently culminated in the discovery that complexes as simple and compact as those between nucleotides (e.g., adenosine triphosphate (ATP)) and Cu(II) ions can be active homogeneous catalysts exhibiting enantioselectivity in Diels-Alder reactions. Although heterogenenized ArMs and enzymes could be more effectively utilized in industrial practice (e.g., in packed bed flow reactors) and could open opportunities for fine-tuning or drastically altering catalytic performance based on confinement effects, facile methods for their preparation remain elusive. Here, it is demonstrated that nucleotides can be supported on nanoporous materials to create enantioselective heterogeneous catalysts. We found that ATP and other nucleotides can be bound to the metal-organic framework (MOF) MIL-101(Cr) through linkages of the terminal phosphate group with Cr(III) of the framework. In the presence of Cu(II) ions, the MOF-supported nucleotides function as stable, reusable, enantioselective heterogeneous catalysts, which in certain cases outperform the corresponding homogeneous nucleotide-based ArMs. Our results demonstrate a simple adsorption-based method to create a new class of enantioselective heterogeneous catalysts. We anticipate that the catalytic properties of MOF-supported nucleotides can be potentially tuned by systematic variation of the type of base and sugar in natural and synthetic nucleotides, and by selection of the confinement environment in the nanoporous host.