De Novo Tailoring Pore Morphologies and Sizes for Different Substrates in a Urea-Containing MOFs Catalytic Platform

To better understand the structure–catalytic property relationship, a platform of urea-containing MOFs with diverse topologies as hydrogen-bonding (H-bond) catalyst has been well established in the present work. During the construction of MOFs, we proposed a new strategy called the isoreticular functionalization approach in which the desired topological net is first considered as a blueprint, and then two predesigned functionalized polydentate ligands link to four different metal clusters by de novo routes to achieve the MOFs with expected pore structure and catalytic sites. By means of this strategy, we successfully synthesized four programmed MOFs (named as <b>URMOF-1–4</b>) with diverse topologies, pore morphologies, and sizes and distribution of active sites. Subsequently, we systematically investigated the Friedel–Crafts reactions of 1-methylpyrrole or 1-methylindole with nitroalkene derivatives with diverse sizes to assess the catalytic properties of the above-mentioned URMOFs. These four URMOFs can act as reusable H-bond catalysts and show varied catalytic capacities and size-selectivity properties. Most significantly, the open morphologies of pores, large channels in the framework, and effective distribution of active sites on the wall of the channel are proved to facilitate catalysis. This urea-containing MOF catalytic platform provides new insight into the catalytic properties of MOFs with the same kind of active sites but diverse topologies, pore morphologies, and sizes and distributions of catalytic sites

Engineering UiO-68-Typed Homochiral Metal–Organic Frameworks for the Enantiomeric Separation of Fmoc-AAs and Mechanism Study

Homochiral metal–organic frameworks (HMOFs) have been widely investigated in the application of enantiomeric separation. Nonetheless, it remains a significant challenge to explore the effect of multiple weak interactions between HMOF adsorbents and chiral adsorbates on enantiomeric separation performance still. In this work, robust chiral amine-alcohol-functionalized UiO-68-typed Zr-HMOFs 1–3 with the same hydrogen-bonding sites but slightly different π-binding sites were prepared for the enantioseparation of amino acid derivatives (Fmoc-AAs) with large π-binding groups. As a consequence of multiple host–guest interactions, these Zr-HMOFs exhibit speedy adsorption and high adsorption capacity for Fmoc-L/D-AAs and dissimilar enantioselectivity for the adsorption of their enantiomers. Materials 1 and 2 exhibit excellent enantioselective separation performance for Fmoc-valine with a single terminal π-binding group, while material 3 displays excellent enantioselective separation performance for Fmoc-phenylalanine and Fmoc-tryptophan with π-binding groups at both ends. As evidently demonstrated by our experimental and density functional theory (DFT) computational results, when the number of π-binding groups preset in the confined chiral space of adsorbents matches the number of π-binding groups of chiral adsorbates, the synergism of π–π or σ–π interactions will increase enantioselectivity; otherwise, the competition interactions from redundant identical binding sites will weaken enantioselectivity. Our case not only provides a tremendously typical system for investigating the collaborative discrimination of multiple weak interactions and exploring the impact of relatively excessive binding sites of HMOF adsorbents or chiral adsorbates on the enantioselective separation performance but also provides guidance for targeted functional modifications of high-performance chiral porous materials

Engineering UiO-68-Typed Homochiral Metal–Organic Frameworks for the Enantiomeric Separation of Fmoc-AAs and Mechanism Study

Homochiral metal–organic frameworks (HMOFs) have been widely investigated in the application of enantiomeric separation. Nonetheless, it remains a significant challenge to explore the effect of multiple weak interactions between HMOF adsorbents and chiral adsorbates on enantiomeric separation performance still. In this work, robust chiral amine-alcohol-functionalized UiO-68-typed Zr-HMOFs 1–3 with the same hydrogen-bonding sites but slightly different π-binding sites were prepared for the enantioseparation of amino acid derivatives (Fmoc-AAs) with large π-binding groups. As a consequence of multiple host–guest interactions, these Zr-HMOFs exhibit speedy adsorption and high adsorption capacity for Fmoc-L/D-AAs and dissimilar enantioselectivity for the adsorption of their enantiomers. Materials 1 and 2 exhibit excellent enantioselective separation performance for Fmoc-valine with a single terminal π-binding group, while material 3 displays excellent enantioselective separation performance for Fmoc-phenylalanine and Fmoc-tryptophan with π-binding groups at both ends. As evidently demonstrated by our experimental and density functional theory (DFT) computational results, when the number of π-binding groups preset in the confined chiral space of adsorbents matches the number of π-binding groups of chiral adsorbates, the synergism of π–π or σ–π interactions will increase enantioselectivity; otherwise, the competition interactions from redundant identical binding sites will weaken enantioselectivity. Our case not only provides a tremendously typical system for investigating the collaborative discrimination of multiple weak interactions and exploring the impact of relatively excessive binding sites of HMOF adsorbents or chiral adsorbates on the enantioselective separation performance but also provides guidance for targeted functional modifications of high-performance chiral porous materials

Engineering UiO-68-Typed Homochiral Metal–Organic Frameworks for the Enantiomeric Separation of Fmoc-AAs and Mechanism Study

Homochiral metal–organic frameworks (HMOFs) have been widely investigated in the application of enantiomeric separation. Nonetheless, it remains a significant challenge to explore the effect of multiple weak interactions between HMOF adsorbents and chiral adsorbates on enantiomeric separation performance still. In this work, robust chiral amine-alcohol-functionalized UiO-68-typed Zr-HMOFs 1–3 with the same hydrogen-bonding sites but slightly different π-binding sites were prepared for the enantioseparation of amino acid derivatives (Fmoc-AAs) with large π-binding groups. As a consequence of multiple host–guest interactions, these Zr-HMOFs exhibit speedy adsorption and high adsorption capacity for Fmoc-L/D-AAs and dissimilar enantioselectivity for the adsorption of their enantiomers. Materials 1 and 2 exhibit excellent enantioselective separation performance for Fmoc-valine with a single terminal π-binding group, while material 3 displays excellent enantioselective separation performance for Fmoc-phenylalanine and Fmoc-tryptophan with π-binding groups at both ends. As evidently demonstrated by our experimental and density functional theory (DFT) computational results, when the number of π-binding groups preset in the confined chiral space of adsorbents matches the number of π-binding groups of chiral adsorbates, the synergism of π–π or σ–π interactions will increase enantioselectivity; otherwise, the competition interactions from redundant identical binding sites will weaken enantioselectivity. Our case not only provides a tremendously typical system for investigating the collaborative discrimination of multiple weak interactions and exploring the impact of relatively excessive binding sites of HMOF adsorbents or chiral adsorbates on the enantioselective separation performance but also provides guidance for targeted functional modifications of high-performance chiral porous materials

In Situ Construction of a Coordination Zirconocene Tetrahedron

The current study describes the first in situ synthesis and characterization of a new family of cationic coordination tetrahedra of both the V₄F₄ and V₄E₆ type, which are constructed by a new building block based on a trinuclear zirconocene moiety and the dicarboxylate or tricarboxylate anions

A Water and Thermally Stable Metal–Organic Framework Featuring Selective CO₂ Adsorption

A 2-fold interpenetrated microporous MOF [Ni₂(C₂O₄)­(L)₂]_<i>n</i>·6<i>n</i>H₂O (HL = 4,2′:4″,2′-terpyridine-4′-carboxylic acid) (<b>1</b>) was synthesized and structurally characterized. <b>1</b> has obvious 1D channels along the crystallographic <i>a</i> and <i>c</i> axes with a pore size of 5.7 to 6.9 Å. Topological analysis shows that the framework of <b>1</b> can be interpreted as a (3,4)-connected net with point symbol (6³)­(6⁵·8). <b>1</b> exhibits high water and thermal stability, which is demonstrated by TGA, PXRD, and VT-PXRD. Additionally, the high temperature structure of <b>1</b>′ (433 K) undoubtedly demonstrates the stability of the framework. More importantly, <b>1</b> shows high selectivities for CO₂ over N₂, H₂, and CH₄ at low pressure and 273 K

In Situ Construction of a Coordination Zirconocene Tetrahedron

The current study describes the first in situ synthesis and characterization of a new family of cationic coordination tetrahedra of both the V₄F₄ and V₄E₆ type, which are constructed by a new building block based on a trinuclear zirconocene moiety and the dicarboxylate or tricarboxylate anions

In Situ Construction of a Coordination Zirconocene Tetrahedron

The current study describes the first in situ synthesis and characterization of a new family of cationic coordination tetrahedra of both the V₄F₄ and V₄E₆ type, which are constructed by a new building block based on a trinuclear zirconocene moiety and the dicarboxylate or tricarboxylate anions

Adsorptive Separation of Methylfuran and Dimethylfuran by a Robust Porous Organic Cage

As vital raw materials in the chemical industry, 2-methylfuran (MeF) and 2,5-dimethylfuran (DMeF) are commonly produced as mixtures. The selective separation of MeF and DMeF is crucial yet challenging, with significant industrial and economic implications. This study presents an energy-efficient separation technique using a robust calix[4]resorcinarene-based supramolecular porous organic cage (POC), CPOC-301, to effectively capture DMeF from an equimolar MeF/DMeF mixture within 2 h, yielding 95.3% purity. The exceptional separation efficiency stems from the superior structural stability of CPOC-301, maintaining its initial porous crystalline structure during separation. Calculations show that CPOC-301 forms more C–H···π hydrogen bonds with DMeF versus MeF, accounting for its DMeF selectivity. CPOC-301 can be easily regenerated via heat under a vacuum and reused for over five adsorption–desorption cycles without significant performance loss. This work introduces an approach to separate similar organic molecules effectively using POC materials

Stabilization of Allylic Amine N‑Oxide through Cocrystallization with Pyrogallol[4]arene

An active allylic amine N-oxide (ANO) molecule was cocrystallized with pyrogallol[4]­arene through intermolecular hydrogen bonds and π···π interactions. Interestingly, [2,3]-Meisenheimer rearrangement of the ANO was suppressed, which was analyzed in detail in the solid state by single crystal X-ray crystallography in varying temperatures. Additionally, this work provides not only a new strategy to stabilize reactive chemicals, but also a unique method to elucidate their structures