Metalloporphyrin-anchored 2D MOF nanosheets as highly accessible heterogeneous photocatalysts towards cytocompatible living radical polymerization

Two-dimensional (2D) metal-organic framework (MOF) nanosheets have emerged as a promising hybrid material due to the highly exposed active sites and high aspect ratio originating from their large lateral dimension and ultrathin thickness. Herein, PCN-134(Zn)-2D (PCN = porous coordination network) nanosheets were investigated as a versatile and effective platform supporting metalloporphyrins to boost their photocatalytic performance for single oxygen generation and living radical polymerization. This method enabled the radical polymerizations of various monomers using low catalyst dosages under a wide range of wavelengths, affording well-defined polymers with high monomer conversions, low polydispersities and tunable functionalities. Compared to three-dimensional (3D) bulk MOF crystals, PCN-134(Zn)-2D exhibited fast polymerization kinetics due to the larger surface area and more accessible catalytic sites within the 2D planar architecture. Most significantly, the polymerization kinetics could be orthogonally regulated by solution pH and light stimuli. Exploiting the oxygen tolerance and fast kinetics, we demonstrated PET-RAFT polymerization at high monomer dilutions and in a human cell culture medium. Illustrations of chain extension and catalyst-recycling test further substantiated the photocatalytic performance of these 2D MOF catalysts outperforming most reported metalloporphyrin-based heterogeneous catalysts towards living radical polymerization.

Automated summary

Two-dimensional (2D) metal-organic framework (MOF) nanosheets have great potential due to their highly exposed active sites and high aspect ratio. In this study, PCN-134(Zn)-2D nanosheets were found to be effective catalysts for enhancing the photocatalytic performance of metalloporphyrins. The polymerization kinetics could be orthogonally regulated by solution pH and light stimuli.