Invisible Silver Guests Boost Order in a Framework That Cyclizes and Deposits Ag₃Sb Nanodots

The infusion of metal guests into (i.e., metalating) the porous medium of metal-organic frameworks (MOFs) is a topical approach to wide-ranging functionalization purposes. We report the notable interactions of AgSbF₆ guests with the designer MOF host ZrL1 [Zr₆O₄(OH)₇(L1)_4.5(H₂O)₄]. (1) The heavy-atom guests of AgSbF6 induce order in the MOF host to allow the movable alkyne side arm to be fully located by X-ray diffraction, but they themselves curiously remain highly disordered and absent in the strucutral model. The enhanced order of the framework can be generally ascribed to interaction of the silver guests with the host alkyne and thioether functions, while the invisible heavy-atom guest represents a new phenomenon in the metalation of open framework materials. (2) The AgSbF₆ guests also participate in the thermocyclization of the vicinal alkyne units of the L1 linker (at 450 °C) and form the rare nanoparticle of Ag₃Sb supported on the concomitantly formed nanographene network. The resulted composite exhibits high electrical conductivity (1.0 S/cm) as well as useful, mitigated catalytic activity for selectively converting nitroarenes into the industrially important azo compounds, i.e., without overshooting to form the amine side products. The heterogeneous/cyclable catalysis entails only the cheap reducing reagents of NaBH₄, ethanol, and water, with yields being generally close to 90%.