25 Jahre retikuläre Chemie

Tetrazine Linkers as Plug-and-Play Tags for General Metal-Organic Framework Functionalization and C60 Conjugation

The value of covalent post-synthetic modification in expanding the chemistry and pore versatility of reticular solids is well documented. Here we use mesoporous crystals of the metal-organic framework (MOF) UiO-68-TZDC to demonstrate the value of tetrazine connectors for all-purpose inverse electron-demand Diels-Alder ligation chemistry. Our results suggest a positive effect of tetrazine reticulation over its reactivity for quantitative one-step functionalization with a broad scope of alkene or alkyne dienophiles into pyridazine and dihydropyridazine frameworks. This permits generating multiple pore environments with diverse chemical functionalities and the expected accessible porosities, that is also extended to the synthesis of crystalline fulleretic materials by covalent conjugation of fullerene molecules.

Syntheses of Covalent Organic Frameworks via a One-Pot Suzuki Coupling and Schiff's Base Reaction for C2 H4 /C3 H6 Separation

Covalent organic frameworks (COFs) featuring permanent porosity, designable topologies, and tailorable functionalities have attracted great interest in the past two decades. Developing efficient modular approaches to rationally constructing COFs from a set of molecules via covalent linking has been long pursued. Herein, we report a facile one-pot strategy to prepare COFs via an irreversible Suzuki coupling reaction followed by a reversible Schiff's base reaction without the need for intermediate isolation. Gram-scale ordered frameworks with kgm topology and rich porosities can be obtained by using diamino-aryl halide and dialdehyde aryl-borate compounds as monomers. The resultant microporous CR-COFs were used for efficient C₂ H₄ /C₃ H₆ separation. This strategy reduces the waste generated and efforts consumed by stepwise reactions and relative purification processes, making the large-scale syntheses of stable COFs feasible. Moreover, it offers a novel modular approach to designing COF materials.

Assembling Metal Organic Layer Composites for High-Performance Electrocatalytic CO2 Reduction to Formate

2D metal-organic-framework (MOF) based composites have emerged as promising candidates for electrocatalysis due to their high structural flexibility and fully exposed active sites. Herein, a freestanding metal-organic layer (MOL) with a 2D kgd (kagome dual) lattice was constructed with abundant surface oxygenate groups serving as anchoring sites to immobilize diverse guests. Taking Bi as an example, tetragonal Bi2 O3 nanowires can be uniformly grown on MOLs after solvothermal treatment, the structural evolution of which was followed by ex situ electron microscopy. The as-prepared Bi2 O3 /MOL exhibits excellent CO2 electroreduction activity towards formate reaching a specific current of 2.3 A mgBi -1 and Faradaic efficiencies of over 85 % with a wide potential range from -0.87 to -1.17 V, far surpassing Bi2 O3 /UiO (a 3D Zr6 -oxo based MOF) and Bi2 O3 /AB (Acetylene Black). Such a post-synthetic modification strategy can be flexibly extended to develop versatile MOL composites, highlighting the superiority of optimizing MOL-based composites for electrocatalysis.