Defects engineering simultaneously enhances activity and recyclability of MOFs in selective hydrogenation of biomass

The development of synthetic methodologies towards enhanced performance in biomass conversion is desirable due to the growing energy demand. Here we design two types of Ru impregnated MIL-100-Cr defect engineered metal-organic frameworks (Ru@DEMOFs) by incorporating defective ligands (DLs), aiming at highly efficient catalysts for biomass hydrogenation. Our results show that Ru@DEMOFs simultaneously exhibit boosted recyclability, selectivity and activity with the turnover frequency being about 10 times higher than the reported values of polymer supported Ru towards D-glucose hydrogenation. This work provides in-depth insights into (i) the evolution of various defects in the cationic framework upon DLs incorporation and Ru impregnation, (ii) the special effect of each type of defects on the electron density of Ru nanoparticles and activation of reactants, and (iii) the respective role of defects, confined Ru particles and metal single active sites in the catalytic performance of Ru@DEMOFs for D-glucose selective hydrogenation as well as their synergistic catalytic mechanism

Defect-Engineered Metal-Organic Frameworks

Defect engineering in metal-organic frameworks (MOFs) is an exciting concept for tailoring material properties, which opens up novel opportunities not only in sorption and catalysis, but also in controlling more challenging physical characteristics such as band gap as well as magnetic and electrical/conductive properties. It is challenging to structurally characterize the inherent or intentionally created defects of various types, and there have so far been few efforts to comprehensively discuss these issues. Based on selected reports spanning the last decades, this Review closes that gap by providing both a concise overview of defects in MOFs, or more broadly coordination network compounds (CNCs), including their classification and characterization, together with the (potential) applications of defective CNCs/MOFs. Moreover, we will highlight important aspects of "defect-engineering" concepts applied for CNCs, also in comparison with relevant solid materials such as zeolites or COFs. Finally, we discuss the future potential of defect-engineered CNCs.status: publishe

Two Silver Coordination Network Compounds with Colorful Photoluminescence

The excitation-wavelength-dependent photoluminescence (EWDP) property of flexible organic ligand 1,4-bis­(2-methyl-imidazol-1-yl)­butane (Bmib) was observed. Herein, Bmib was chosen as a bridge linker to react with AgX (X = Br and I) to synthesize novel coordination network compounds (CNCs) with interesting EWDP properties. As anticipated, under the same hydrothermal synthesis conditions, two new isomorphic CNCs, i.e. [Ag₂(Bmib)­Br₂]_∞ (<i><b>IAM16-1</b></i>) and [Ag₂(Bmib)­I₂]_∞ (<i><b>IAM16-2</b></i>), as the first examples of CNCs showing EWDP properties, have been obtained. The EWDP properties may be attributed to the stretch and rotation of the long -(CH₂)₄- chains of Bmib and the spatial orientation adjustment of the methyl group of each imidazole ring at different excitation wavelengths. It is a great challenge to point out the emission mechanisms of CNCs merely from the experimental results due to their multiple charge transfer routes. To address this issue, we adopt DFT calculations to pursue in-depth investigation of the emission mechanisms for <i><b>IAM16-1</b></i> and <i><b>IAM16-2</b></i>, respectively

Two Silver Coordination Network Compounds with Colorful Photoluminescence

The excitation-wavelength-dependent photoluminescence (EWDP) property of flexible organic ligand 1,4-bis­(2-methyl-imidazol-1-yl)­butane (Bmib) was observed. Herein, Bmib was chosen as a bridge linker to react with AgX (X = Br and I) to synthesize novel coordination network compounds (CNCs) with interesting EWDP properties. As anticipated, under the same hydrothermal synthesis conditions, two new isomorphic CNCs, i.e. [Ag₂(Bmib)­Br₂]_∞ (<i><b>IAM16-1</b></i>) and [Ag₂(Bmib)­I₂]_∞ (<i><b>IAM16-2</b></i>), as the first examples of CNCs showing EWDP properties, have been obtained. The EWDP properties may be attributed to the stretch and rotation of the long -(CH₂)₄- chains of Bmib and the spatial orientation adjustment of the methyl group of each imidazole ring at different excitation wavelengths. It is a great challenge to point out the emission mechanisms of CNCs merely from the experimental results due to their multiple charge transfer routes. To address this issue, we adopt DFT calculations to pursue in-depth investigation of the emission mechanisms for <i><b>IAM16-1</b></i> and <i><b>IAM16-2</b></i>, respectively

Two Silver Coordination Network Compounds with Colorful Photoluminescence

The excitation-wavelength-dependent photoluminescence (EWDP) property of flexible organic ligand 1,4-bis­(2-methyl-imidazol-1-yl)­butane (Bmib) was observed. Herein, Bmib was chosen as a bridge linker to react with AgX (X = Br and I) to synthesize novel coordination network compounds (CNCs) with interesting EWDP properties. As anticipated, under the same hydrothermal synthesis conditions, two new isomorphic CNCs, i.e. [Ag₂(Bmib)­Br₂]_∞ (<i><b>IAM16-1</b></i>) and [Ag₂(Bmib)­I₂]_∞ (<i><b>IAM16-2</b></i>), as the first examples of CNCs showing EWDP properties, have been obtained. The EWDP properties may be attributed to the stretch and rotation of the long -(CH₂)₄- chains of Bmib and the spatial orientation adjustment of the methyl group of each imidazole ring at different excitation wavelengths. It is a great challenge to point out the emission mechanisms of CNCs merely from the experimental results due to their multiple charge transfer routes. To address this issue, we adopt DFT calculations to pursue in-depth investigation of the emission mechanisms for <i><b>IAM16-1</b></i> and <i><b>IAM16-2</b></i>, respectively

A Series of Lanthanide-Based Metal–Organic Frameworks: Synthesis, Structures, and Multicolor Tuning of Single Component

The single component (SC) white-light emitting (WLE) metal-organic frameworks based on europium (Eu-MOFs), which could be applied in lighting and display, have drawn great attention but have rarely been exploited. In this work, we dedicated to design and synthesize SC-WLE Eu-MOFs via a dichromatic strategy on the balance of simultaneous ligand-based and Eu-based emissions. The Eu-MOF {[Eu₄(obb)₆(H₂O)₉]·(H₂O)}_∞ (<i><b>IAM16–3</b></i>) generated via the self-assembly of the flexible ligand 4,4′-oxybisbenzoic acid (H₂obb) and europium ions displays fascinating excitation-wavelength-dependent photoluminescence (EWDP) property. Upon different excitation wavelengths, tunable WLE through manipulating the intensity ratio of characteristic emissions of Eu³⁺ ions and ligand-based emissions was performed. To the best of our knowledge, this is the first example for Eu-MOFs to yield SC-WLE stemming from EWDP property. Three isomorphic lanthanide-based MOFs (LnMOFs), that is, {[Ln₄(obb)₆(H₂O)₉]·(H₂O)}_∞ (Eu³⁺: <i><b>IAM16–3</b></i>; Tb³⁺: <i><b>IAM16–4</b></i>; Dy³⁺: <i><b>IAM16–5</b></i>) based on the flexible bridging linker, that is, 4,4′-oxybisbenzoic acid (H₂obb), were obtained. The Eu-MOF, showing with EWDP property, is the first example of SC WLE Eu-MOFs via a dichromatic strategy on the balance of the simultaneous ligand-based and Eu­(III)-based emissions at different excitation wavelengths

Two Silver Coordination Network Compounds with Colorful Photoluminescence

The excitation-wavelength-dependent photoluminescence (EWDP) property of flexible organic ligand 1,4-bis­(2-methyl-imidazol-1-yl)­butane (Bmib) was observed. Herein, Bmib was chosen as a bridge linker to react with AgX (X = Br and I) to synthesize novel coordination network compounds (CNCs) with interesting EWDP properties. As anticipated, under the same hydrothermal synthesis conditions, two new isomorphic CNCs, i.e. [Ag₂(Bmib)­Br₂]_∞ (<i><b>IAM16-1</b></i>) and [Ag₂(Bmib)­I₂]_∞ (<i><b>IAM16-2</b></i>), as the first examples of CNCs showing EWDP properties, have been obtained. The EWDP properties may be attributed to the stretch and rotation of the long -(CH₂)₄- chains of Bmib and the spatial orientation adjustment of the methyl group of each imidazole ring at different excitation wavelengths. It is a great challenge to point out the emission mechanisms of CNCs merely from the experimental results due to their multiple charge transfer routes. To address this issue, we adopt DFT calculations to pursue in-depth investigation of the emission mechanisms for <i><b>IAM16-1</b></i> and <i><b>IAM16-2</b></i>, respectively