A series of zirconium polyphenolate-decorated-(metallo)porphyrin metal-organic frameworks (MOFs), ZrPP-n (n = 1, 2), featuring infinite Zr -oxo chains linked via polyphenolate groups on four peripheries of eclipse-arranged porphyrin macrocycles, are successfully constructed through a top-down process from simulation to synthesis. These are the unusual examples of Zr-MOFs (or MOFs in general) based on phenolic porphyrins, instead of commonly known carboxylate-based types. Representative ZrPP-1 not only exhibits strong acid resistance (pH = 1, HCl) but also remains intact even when immersed in saturated NaOH solution (≈20 m), an exceptionally large range of pH resistance among MOFs. The metallation at the porphyrin core gives rise to materials with enhanced sorption and catalytic properties. In particular, ZrPP-1-Co, with precise and uniform distribution of active centers, exhibits not only high CO trapping capability (≈90 cm g at 1 atm, 273 K, among the highest in Zr-MOFs) but also high photocatalytic activity for reduction of CO into CO (≈14 mmol g h ) and high selectivity over CH (>96.4%) without any cocatalyst under visible-light irradiation (λ > 420 nm). Given the strong chemical resistance under extreme alkali conditions, these catalysts can be recycled without appreciable loss of activity. The possible mechanism for photocatalytic reduction of CO -to-CO over ZrPP-1-Co is also proposed.
The effective capture and storage of radioiodine are of worldwide interest for sustainable nuclear energy. However, the direct observation of ambiguous binding sites that accommodate iodine is extremely rare. We presented herein a crystallographic visualization of the binding of iodine within mesoporous cages assembled from aluminum molecular rings. These nanocages are formed through π−π interactions between adjacent aluminum molecular rings. Compared with the general nanotubes arrangement, the supramolecular nanocage isomer exhibits better iodine adsorption behavior. The robust molecular nanocages demonstrate a high iodine vapor saturation uptake capacity of 50.3 wt % at 80 °C. Furthermore, the resulting adsorbent can be recycled. Singlecrystal X-ray diffraction reveals binding sites of molecular I 2 within the pores of the phenyl-based linkers stabilized by the strong I•••π interactions. These compounds represent an excellent model to deduce the trapping mechanism of guest molecules interacting with the host. In addition, this work develops a promising cluster-based aluminum material as iodine adsorbents.
Titanium(IV)-based metal-organic frameworks (Ti-MOFs) have received significant attention in recent years because of their numerous photocatalytic applications; however, the synthesis of new Ti-MOFs with precise crystal structures is still challenging. Herein, three new Ti-MOFs with single-crystal structures (denoted as FIR-125−FIR-127) are rationally synthesized by employing a large Ti 44 -oxo cluster as the precursor to assembly with the organic ligand. Big single-crystals can be successfully obtained and structurally determined by single-crystal X-ray diffraction. During the synthesis, the large Ti 44 -oxo cluster is transferred to small Ti 8 O 8 (CO 2 ) 16 building units in the Ti-MOF. In addition, FIR-125 exhibit high stability, permanent porosity, and photocatalytic activity. This work provides a new strategy toward the big crystal growth of Ti-MOFs through the slow transformation of large titanium-oxo clusters.
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