CuBTTri (where H3BTTri = 1,3,5-tris(1H-1,2,3-triazol-5-yl)benzene), is an established copper metal-organic framework (MOF) that is known to be stable under aqueous conditions. Because of its stability in water, CuBTTri can be safely used in medical devices without risk of acute copper toxicity. Our lab has been interested in the use of CuBTTri for the catalytic generation of nitric oxide (NO) from endogenous sources to drive vasodilation, reduction of biofilms on medical devices, and antimicrobial activity. However, in many catalytic MOF systems, pore apertures of MOFs are too narrow to allow for substrate diffusion into the channels to access intrapore metal sites, restricting catalytic activity to the external surface area of the particle. This limits catalytic activity to approximately 1.3% of the metal sites on the MOF particles 600 +/- 400 nm in size. To address this, CuBTTri octahedra have been redesigned into MOF nanosheets, reducing the amount of internal volume while increasing external surface area. Our initial attempt to use a bottom-up, three-layer method to synthesize CuBTTri MOF nanosheets was unsuccessful. Since CuBTTri was not conducive to forming nanosheets, a modified ligand was used, creating CuBDTri (where H2BDTri = 1,4-di(1H-1,2,3-triazol-5-yl)benzene), as the H2BDTri ligand more readily promoted the growth of the MOF particle in two-dimensions. The CuBDTri MOF nanosheets were found to be 40-600 nm in length with an average thickness of 43 nm and retained the water-stability of CuBTTri. From preliminary studies, it has been found that when used for the catalytic generation of NO from S-nitrosoglutathione, the CuBDTri MOF nanosheets were more active than CuBTTri octahedra on a per-total-Cu-atom basis. The success of this project thus far shows that both the synthetic method and the design of the ligand are both major factors that influence the morphology of the MOF particle. Furthermore, this work has produced a novel, water-stable, catalytically active Cu-MOF, CuBDTri for the first time as a nanosheet and as a nanocrystal that has also been shown to be more catalytically active than the CuBTTri octahedra counterpart.

Reshaping the future of MOF catalysis: Modifying the morphology of MOF particles for enhanced catalytic activity

ACS Spring 2022

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