Metal-organic frameworks (MOFs) have been extensively used for single-site catalysis and light harvesting, but their application in multicomponent photocatalysis is unexplored. We report here the successful incorporation of an Ir photoredox catalyst and a Ni cross-coupling catalyst into a stable Zr MOF, Zr -Ir-Ni, to efficiently catalyze C-S bond formation between various aryl iodides and thiols. The proximity of the Ir and Ni catalytic components to each other (ca. 0.6 nm) in Zr -Ir-Ni greatly facilitates electron and thiol radical transfers from Ir to Ni centers to reach a turnover number of 38 500, an order of magnitude higher than that of its homogeneous counterpart. This work highlights the opportunity in merging photoredox and organometallic catalysts in MOFs to effect challenging organic transformations.
We report the design of a new multifunctional metal−organic layer (MOL), Hf 12 -Ir-OTf, comprising triflate (OTf)capped Hf 12 secondary building units (SBUs) and photosensitizing Ir(DBB)[dF(CF 3 )ppy] 2 + [DBB-Ir-F, DBB = 4,4′-di(4benzoato)-2,2′-bipyridine; dF(CF 3 )ppy = 2-(2,4-difluorophenyl)-5-(trifluoromethyl)pyridine] bridging ligands. Hf 12 -Ir-OTf effectively catalyzed dehydrogenative cross-couplings of heteroarenes with ethers, amines, and unactivated alkanes with turnover numbers of 930, 790, and 950, respectively. Hf 12 -Ir-OTf also competently catalyzed late-stage functionalization of bioactive and drug molecules such as caffeine, Fasudil, and Metyrapone. The superior catalytic performance of Hf 12 -Ir-OTf over a mixture of photoredox catalyst and stoichiometric amounts of Brønsted acids or substoichiometric amounts (20 mol %) of Lewis acids is attributed to the close proximity (1.2 nm) between photoredox and Lewis acid catalysts in Hf 12 -Ir-OTf, which not only facilitates the reaction between the carbon radical and the activated heteroarene but also accelerates the electron transfer from the nitrogen radical intermediate to the Ir(IV) species in the catalytic cycle.
Herein we report that dimensional
reduction from three-dimensional
nanoscale metal–organic frameworks (nMOFs) to two-dimensional
nanoscale metal–organic layers (nMOLs) increases the frequency
of encounters between photosensitizers and oxygen and facilitates
the diffusion of singlet oxygen from the nMOL to significantly enhance
photodynamic therapy. The nMOFs and nMOLs share the same M12–oxo (M = Zr, Hf) secondary building units and 5,15-di-p-benzoatoporphyrin (DBP) ligands but exhibit three-dimensional
and two-dimensional topologies, respectively. Molecular dynamics simulations
and experimental studies revealed that the nMOLs with a monolayer
morphology enhanced the generation of reactive oxygen species and
exhibited over an order of magnitude higher cytotoxicity over the
nMOFs. In a mouse model of triple-negative breast cancer, Hf-DBP nMOL
showed 49.1% more tumor inhibition, an 80% higher cure rate, and 16.3-fold
lower metastasis potential than Hf-DBP nMOF.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.