skip to main content


Search for: All records

Creators/Authors contains: "Wang, Xingjie"

Note: When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external site maintained by the publisher. Some full text articles may not yet be available without a charge during the embargo (administrative interval).
What is a DOI Number?

Some links on this page may take you to non-federal websites. Their policies may differ from this site.

  1. Abstract

    The interactions between uranium and non‐innocent organic species are an essential component of fundamental uranium redox chemistry. However, they have seldom been explored in the context of multidimensional, porous materials. Uranium‐based metal–organic frameworks (MOFs) offer a new angle to study these interactions, as these self‐assembled species stabilize uranium species through immobilization by organic linkers within a crystalline framework, while potentially providing a method for adjusting metal oxidation state through coordination of non‐innocent linkers. We report the synthesis of the MOFNU‐1700, assembled from U4+‐paddlewheel nodes and catecholate‐based linkers. We propose this highly unusual structure, which contains two U4+ions in a paddlewheel built from four linkers—a first among uranium materials—as a result of extensive characterization via powder X‐ray diffraction (PXRD), sorption, transmission electron microscopy (TEM), and thermogravimetric analysis (TGA), in addition to density functional theory (DFT) calculations.

     
    more » « less
  2. Abstract

    The interactions between uranium and non‐innocent organic species are an essential component of fundamental uranium redox chemistry. However, they have seldom been explored in the context of multidimensional, porous materials. Uranium‐based metal–organic frameworks (MOFs) offer a new angle to study these interactions, as these self‐assembled species stabilize uranium species through immobilization by organic linkers within a crystalline framework, while potentially providing a method for adjusting metal oxidation state through coordination of non‐innocent linkers. We report the synthesis of the MOFNU‐1700, assembled from U4+‐paddlewheel nodes and catecholate‐based linkers. We propose this highly unusual structure, which contains two U4+ions in a paddlewheel built from four linkers—a first among uranium materials—as a result of extensive characterization via powder X‐ray diffraction (PXRD), sorption, transmission electron microscopy (TEM), and thermogravimetric analysis (TGA), in addition to density functional theory (DFT) calculations.

     
    more » « less
  3. null (Ed.)
    A huge challenge facing scientists is the development of adsorbent materials that exhibit ultrahigh porosity but maintain balance between gravimetric and volumetric surface areas for the onboard storage of hydrogen and methane gas—alternatives to conventional fossil fuels. Here we report the simulation-motivated synthesis of ultraporous metal–organic frameworks (MOFs) based on metal trinuclear clusters, namely, NU-1501-M (M = Al or Fe). Relative to other ultraporous MOFs, NU-1501-Al exhibits concurrently a high gravimetric Brunauer−Emmett−Teller (BET) area of 7310 m 2 g −1 and a volumetric BET area of 2060 m 2 cm −3 while satisfying the four BET consistency criteria. The high porosity and surface area of this MOF yielded impressive gravimetric and volumetric storage performances for hydrogen and methane: NU-1501-Al surpasses the gravimetric methane storage U.S. Department of Energy target (0.5 g g −1 ) with an uptake of 0.66 g g −1 [262 cm 3 (standard temperature and pressure, STP) cm −3 ] at 100 bar/270 K and a 5- to 100-bar working capacity of 0.60 g g −1 [238 cm 3 (STP) cm −3 ] at 270 K; it also shows one of the best deliverable hydrogen capacities (14.0 weight %, 46.2 g liter −1 ) under a combined temperature and pressure swing (77 K/100 bar → 160 K/5 bar). 
    more » « less
  4. Abstract

    Proteins immobilized in metal–organic frameworks (MOFs) often show extraordinary stability. However, most efforts to immobilize proteins in MOFs have only been exploratory. Herein, we present the first systematic study on the thermodynamics of protein immobilization in MOFs. Using insulin as a probe, we leveraged isothermal titration calorimetry (ITC) to investigate how topology, pore size, and hydrophobicity of MOFs influence immobilization. ITC data obtained from the encapsulation of insulin in a series of Zr‐MOFs reveals that MOFs provide proteins with a hydrophobic stabilizing microenvironment, making the encapsulation entropically driven. In particular, the pyrene‐based NU‐1000 tightly encapsulates insulin in its ideally sized mesopores and stabilizes insulin through π‐π stacking interactions, resulting in the most enthalpically favored encapsulation process among this series. This study reveals critical insights into the structure–property relationships of protein immobilization.

     
    more » « less
  5. Abstract

    Proteins immobilized in metal–organic frameworks (MOFs) often show extraordinary stability. However, most efforts to immobilize proteins in MOFs have only been exploratory. Herein, we present the first systematic study on the thermodynamics of protein immobilization in MOFs. Using insulin as a probe, we leveraged isothermal titration calorimetry (ITC) to investigate how topology, pore size, and hydrophobicity of MOFs influence immobilization. ITC data obtained from the encapsulation of insulin in a series of Zr‐MOFs reveals that MOFs provide proteins with a hydrophobic stabilizing microenvironment, making the encapsulation entropically driven. In particular, the pyrene‐based NU‐1000 tightly encapsulates insulin in its ideally sized mesopores and stabilizes insulin through π‐π stacking interactions, resulting in the most enthalpically favored encapsulation process among this series. This study reveals critical insights into the structure–property relationships of protein immobilization.

     
    more » « less
  6. Abstract

    The fabrication of MOF polymer composite materials enables the practical applications of MOF‐based technology, in particular for protective suits and masks. However, traditional production methods typically require organic solvent for processing which leads to environmental pollution, low‐loading efficiency, poor accessibility, and loss of functionality due to poor solvent resistance properties. For the first time, we have developed a microbial synthesis strategy to prepare a MOF/bacterial cellulose nanofiber composite sponge. The prepared sponge exhibited a hierarchically porous structure, high MOF loading (up to ≈90 %), good solvent resistance, and high catalytic activity for the liquid‐ and solid‐state hydrolysis of nerve agent simulants. Moreover, the MOF/ bacterial cellulose composite sponge reported here showed a nearly 8‐fold enhancement in the protection against an ultra‐toxic nerve agent (GD) in permeability studies as compared to a commercialized adsorptive carbon cloth. The results shown here present an essential step toward the practical application of MOF‐based protective gear against nerve agents.

     
    more » « less
  7. Abstract

    The fabrication of MOF polymer composite materials enables the practical applications of MOF‐based technology, in particular for protective suits and masks. However, traditional production methods typically require organic solvent for processing which leads to environmental pollution, low‐loading efficiency, poor accessibility, and loss of functionality due to poor solvent resistance properties. For the first time, we have developed a microbial synthesis strategy to prepare a MOF/bacterial cellulose nanofiber composite sponge. The prepared sponge exhibited a hierarchically porous structure, high MOF loading (up to ≈90 %), good solvent resistance, and high catalytic activity for the liquid‐ and solid‐state hydrolysis of nerve agent simulants. Moreover, the MOF/ bacterial cellulose composite sponge reported here showed a nearly 8‐fold enhancement in the protection against an ultra‐toxic nerve agent (GD) in permeability studies as compared to a commercialized adsorptive carbon cloth. The results shown here present an essential step toward the practical application of MOF‐based protective gear against nerve agents.

     
    more » « less