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Rodney S Ruoff - One of the best experts on this subject based on the ideXlab platform.

  • partial oxidation induced electrical conductivity and paramagnetism in a ni ii tetraaza 14 annulene linked metal organic framework
    Journal of the American Chemical Society, 2019
    Co-Authors: Yi Jiang, Inseon Oh, Onur Buyukcakir, Xiong Chen, Ming Huang, Won Kyung Seong, Sang Kyu Kwak, Rodney S Ruoff
    Abstract:

    We report the synthesis and characterization of a two-dimensional (2D) conjugated Ni(II) tetraaza[14]annulene-linked metal organic framework (NiTAA-MOF) where NiTAA is a macrocyclic MN4 (M = metal, N = Nitrogen) Compound. The structure of NiTAA-MOF was elucidated by Fourier-transform infrared, X-ray photoemission, and X-ray diffraction spectroscopies, in combination with density functional theory (DFT) calculations. When chemically oxidized by iodine, the insulating bulk NiTAA-MOF (σ < 10–10 S/cm) exhibits an electrical conductivity of 0.01 S/cm at 300 K, demonstrating the vital role of ligand oxidation in the electrical conductivity of 2D MOFs. Magnetization measurements show that iodine-doped NiTAA-MOF is paramagnetic with weak antiferromagnetic coupling due to the presence of organic radicals of oxidized ligands and high-spin Ni(II) sites of the missing-linker defects. In addition to providing further insights into the origin of the induced electrical conductivity in 2D MOFs, both pristine and iodine-d...

Yi Jiang - One of the best experts on this subject based on the ideXlab platform.

  • partial oxidation induced electrical conductivity and paramagnetism in a ni ii tetraaza 14 annulene linked metal organic framework
    Journal of the American Chemical Society, 2019
    Co-Authors: Yi Jiang, Inseon Oh, Onur Buyukcakir, Xiong Chen, Ming Huang, Won Kyung Seong, Sang Kyu Kwak, Rodney S Ruoff
    Abstract:

    We report the synthesis and characterization of a two-dimensional (2D) conjugated Ni(II) tetraaza[14]annulene-linked metal organic framework (NiTAA-MOF) where NiTAA is a macrocyclic MN4 (M = metal, N = Nitrogen) Compound. The structure of NiTAA-MOF was elucidated by Fourier-transform infrared, X-ray photoemission, and X-ray diffraction spectroscopies, in combination with density functional theory (DFT) calculations. When chemically oxidized by iodine, the insulating bulk NiTAA-MOF (σ < 10–10 S/cm) exhibits an electrical conductivity of 0.01 S/cm at 300 K, demonstrating the vital role of ligand oxidation in the electrical conductivity of 2D MOFs. Magnetization measurements show that iodine-doped NiTAA-MOF is paramagnetic with weak antiferromagnetic coupling due to the presence of organic radicals of oxidized ligands and high-spin Ni(II) sites of the missing-linker defects. In addition to providing further insights into the origin of the induced electrical conductivity in 2D MOFs, both pristine and iodine-d...

  • Partial Oxidation-Induced Electrical Conductivity and Paramagnetism in a Ni(II) Tetraaza[14]annulene-Linked Metal Organic Framework
    'American Chemical Society (ACS)', 2019
    Co-Authors: Yi Jiang, Oh Inseon, Joo, Se Hun, Buyukcakir Onur, Chen Xiong, Lee, Sun Hwa, Huang Ming, Seong, Won Kyung, Kwak, Sang Kyu, Yoo Jung-woo
    Abstract:

    We report the synthesis and characterization of a two-dimensional (2D) conjugated Ni(II) tetraaza[14]annulene-linked metal organic framework (NiTAA-MOF) where NiTAA is a macrocyclic MN4 (M = metal, N = Nitrogen) Compound. The structure of NiTAA-MOF was elucidated by Fourier-transform infrared, X-ray photoemission, and X-ray diffraction spectroscopies, in combination with density functional theory (DFT) calculations. When chemically oxidized by iodine, the insulating bulk NiTAA-MOF (?? < 10???10 S/cm) exhibits an electrical conductivity of 0.01 S/cm at 300 K, demonstrating the vital role of ligand oxidation in the electrical conductivity of 2D MOFs. Magnetization measurements show that iodine-doped NiTAA-MOF is paramagnetic with weak antiferromagnetic coupling due to the presence of organic radicals of oxidized ligands and high-spin Ni(II) sites of the missing-linker defects. In addition to providing further insights into the origin of the induced electrical conductivity in 2D MOFs, both pristine and iodine-doped NiTAA-MOF synthesized in this work could find potential applications in areas such as catalase mimics, catalysis, energy storage, and dynamic nuclear polarization-nuclear magnetic resonance (DNP-NMR)

  • Partial Oxidation-Induced Electrical Conductivity and Paramagnetism in a Ni(II) Tetraaza[14]annulene-Linked Metal Organic Framework
    AMER CHEMICAL SOC, 2019
    Co-Authors: Yi Jiang, Onur Buyukcakir, Xiong Chen, Ming Huang, Won Kyung Seong, Sang Kyu Kwak, Se Hun Joo, Sun Hwa Lee, Jung-woo Yoo
    Abstract:

    © 2019 American Chemical Society.We report the synthesis and characterization of a two-dimensional (2D) conjugated Ni(II) tetraaza[14]annulene-linked metal organic framework (NiTAA-MOF) where NiTAA is a macrocyclic MN4 (M = metal, N = Nitrogen) Compound. The structure of NiTAA-MOF was elucidated by Fourier-transform infrared, X-ray photoemission, and X-ray diffraction spectroscopies, in combination with density functional theory (DFT) calculations. When chemically oxidized by iodine, the insulating bulk NiTAA-MOF (σ < 10-10 S/cm) exhibits an electrical conductivity of 0.01 S/cm at 300 K, demonstrating the vital role of ligand oxidation in the electrical conductivity of 2D MOFs. Magnetization measurements show that iodine-doped NiTAA-MOF is paramagnetic with weak antiferromagnetic coupling due to the presence of organic radicals of oxidized ligands and high-spin Ni(II) sites of the missing-linker defects. In addition to providing further insights into the origin of the induced electrical conductivity in 2D MOFs, both pristine and iodine-doped NiTAA-MOF synthesized in this work could find potential applications in areas such as catalase mimics, catalysis, energy storage, and dynamic nuclear polarization-nuclear magnetic resonance (DNP-NMR

Baojun Qu - One of the best experts on this subject based on the ideXlab platform.

  • expandable graphite systems for halogen free flame retarding of polyolefins i flammability characterization and synergistic effect
    Journal of Applied Polymer Science, 2001
    Co-Authors: Rongcai Xie, Baojun Qu
    Abstract:

    The use of some types of expandable graphite (EG) as an intumescent flame-retardant additive in polyolefins was studied using the cone calorimeter test (CCT), thermogravimetric analysis (TGA), the limiting oxygen index (LOI), and the-UL 94 test and through measurement of EG's mechanical and electrical properties. The present study has shown that some suitable EG systems combined with other organic and inorganic halogen-free flame-retardant (HFFR) additives apparently can improve the flame-retardant capacity with good mechanical properties of polyolefin blends. For linear low-density polyethylene and/or ethylene vinyl acetate/EG/HFFR blends the limiting oxygen index can reach a rating above 29, and the UL-94 test can produce a value of V–0. The CCT and TGA data show that the EG and EG/HFFR additives not only promoted the formation of carbonaceous char but also greatly decreased the heat release rate and the effective heat of combustion and increased the residues after burning. The synergistic effect of EG with other HFFR additives, such as zinc borate, the phosphorus–Nitrogen Compound NP28, and microcapsulated red phosphorus is examined and discussed in detail in this article. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1181–1189, 2001

  • dynamic ftir studies of thermo oxidation of expandable graphite based halogen free flame retardant lldpe blends
    Polymer Degradation and Stability, 2001
    Co-Authors: Rongcai Xie, Baojun Qu, Keliang Hu
    Abstract:

    Abstract The dynamic thermo-oxidative degradation of expandable graphite (EG)-based intumescent halogen-free flame retardant (HFFR) LLDPE blends in the condensed phase at 300 or 400°C has been studied in situ by real time Fourier transform infrared spectroscopy. The kinetic characteristics and dynamic changes of various kinds of pyrolysis products during the thermo-oxidative degradation were examined extensively for several LLDPE/EG blends with different HFFR additives, such as the phosphorus–Nitrogen Compound NP28, ammonium polyphosphate (APP), red phosphorus (RP), and zinc borate (ZB). It has been found (i) that the dynamic monitoring of the LLDPE/EG/HFFR blends during the pyrolysis shows that the breakdown of LLDPE main chains and formation of various kinds of carbonyl products increase with increasing thermo-oxidation time and temperature; the latter have been identified as carboxylic acids, ketone, lactone and cyclic anhydrides; (ii) that the fast formation rate and high initial concentrations of P–O–P and P–O–C products in the phosphorus-containing HFFR systems have a crucial importance for decreasing the thermo-oxidative degradation rate of LLDPE efficiently (the NP28 system is the most efficient in the present study); and (iii) that the pyrolysis temperature has a significant effect on the efficiency of flame retardants, which requires the LLDPE/EG/HFFR formulation should be optimized at certain temperature range in order to form compact intumescent charred layers immediately at the beginning of the thermo-oxidative degradation of the LLDPE blends.

  • synergistic effects of silicotungistic acid on intumescent flame retardant polypropylene
    Polymer Degradation and Stability, 2001
    Co-Authors: Qiang Wu, Baojun Qu
    Abstract:

    Abstract The synergistic effects of silicotungistic acid (SiW 12 ) as a catalyst in polypropylene (PP) flame-retarded by the intumescent flame-retarder (IFR) based on the NP28 phosphorus-Nitrogen Compound were studied using the limiting oxygen index (LOI), the UL-94 test, thermogravimetric analysis (TGA), real time Fourier transform infrared (FTIR), laser Raman spectroscopy (LRS), and scanning electron microscopy (SEM). The LOI data show that SiW 12 added to PP/IFR systems has a synergistic FR effect with NP28. The TGA data show that SiW 12 increases the thermal stability of the PP/IFR systems at high temperature ( T >500 °C). The FTIR results provide positive evidence that IFR can improve the thermal stability of PP and SiW 12 and can efficiently promote the formation of charred layers with phosphocarbonaceous structures. The LRS measurements provide useful information on the carbonaceous microstructures. The morphological structures observed by SEM have demonstrated that SiW 12 can promote formation of compact intumescent charred layers. Thus, a suitable amount of SiW 12 plays a synergistic effects with the IFR in increasing the LOI value and the thermal stability at high temperature and promoting the formation of charred structures in the PP blends.

Won Kyung Seong - One of the best experts on this subject based on the ideXlab platform.

  • partial oxidation induced electrical conductivity and paramagnetism in a ni ii tetraaza 14 annulene linked metal organic framework
    Journal of the American Chemical Society, 2019
    Co-Authors: Yi Jiang, Inseon Oh, Onur Buyukcakir, Xiong Chen, Ming Huang, Won Kyung Seong, Sang Kyu Kwak, Rodney S Ruoff
    Abstract:

    We report the synthesis and characterization of a two-dimensional (2D) conjugated Ni(II) tetraaza[14]annulene-linked metal organic framework (NiTAA-MOF) where NiTAA is a macrocyclic MN4 (M = metal, N = Nitrogen) Compound. The structure of NiTAA-MOF was elucidated by Fourier-transform infrared, X-ray photoemission, and X-ray diffraction spectroscopies, in combination with density functional theory (DFT) calculations. When chemically oxidized by iodine, the insulating bulk NiTAA-MOF (σ < 10–10 S/cm) exhibits an electrical conductivity of 0.01 S/cm at 300 K, demonstrating the vital role of ligand oxidation in the electrical conductivity of 2D MOFs. Magnetization measurements show that iodine-doped NiTAA-MOF is paramagnetic with weak antiferromagnetic coupling due to the presence of organic radicals of oxidized ligands and high-spin Ni(II) sites of the missing-linker defects. In addition to providing further insights into the origin of the induced electrical conductivity in 2D MOFs, both pristine and iodine-d...

  • Partial Oxidation-Induced Electrical Conductivity and Paramagnetism in a Ni(II) Tetraaza[14]annulene-Linked Metal Organic Framework
    AMER CHEMICAL SOC, 2019
    Co-Authors: Yi Jiang, Onur Buyukcakir, Xiong Chen, Ming Huang, Won Kyung Seong, Sang Kyu Kwak, Se Hun Joo, Sun Hwa Lee, Jung-woo Yoo
    Abstract:

    © 2019 American Chemical Society.We report the synthesis and characterization of a two-dimensional (2D) conjugated Ni(II) tetraaza[14]annulene-linked metal organic framework (NiTAA-MOF) where NiTAA is a macrocyclic MN4 (M = metal, N = Nitrogen) Compound. The structure of NiTAA-MOF was elucidated by Fourier-transform infrared, X-ray photoemission, and X-ray diffraction spectroscopies, in combination with density functional theory (DFT) calculations. When chemically oxidized by iodine, the insulating bulk NiTAA-MOF (σ < 10-10 S/cm) exhibits an electrical conductivity of 0.01 S/cm at 300 K, demonstrating the vital role of ligand oxidation in the electrical conductivity of 2D MOFs. Magnetization measurements show that iodine-doped NiTAA-MOF is paramagnetic with weak antiferromagnetic coupling due to the presence of organic radicals of oxidized ligands and high-spin Ni(II) sites of the missing-linker defects. In addition to providing further insights into the origin of the induced electrical conductivity in 2D MOFs, both pristine and iodine-doped NiTAA-MOF synthesized in this work could find potential applications in areas such as catalase mimics, catalysis, energy storage, and dynamic nuclear polarization-nuclear magnetic resonance (DNP-NMR

Sang Kyu Kwak - One of the best experts on this subject based on the ideXlab platform.

  • partial oxidation induced electrical conductivity and paramagnetism in a ni ii tetraaza 14 annulene linked metal organic framework
    Journal of the American Chemical Society, 2019
    Co-Authors: Yi Jiang, Inseon Oh, Onur Buyukcakir, Xiong Chen, Ming Huang, Won Kyung Seong, Sang Kyu Kwak, Rodney S Ruoff
    Abstract:

    We report the synthesis and characterization of a two-dimensional (2D) conjugated Ni(II) tetraaza[14]annulene-linked metal organic framework (NiTAA-MOF) where NiTAA is a macrocyclic MN4 (M = metal, N = Nitrogen) Compound. The structure of NiTAA-MOF was elucidated by Fourier-transform infrared, X-ray photoemission, and X-ray diffraction spectroscopies, in combination with density functional theory (DFT) calculations. When chemically oxidized by iodine, the insulating bulk NiTAA-MOF (σ < 10–10 S/cm) exhibits an electrical conductivity of 0.01 S/cm at 300 K, demonstrating the vital role of ligand oxidation in the electrical conductivity of 2D MOFs. Magnetization measurements show that iodine-doped NiTAA-MOF is paramagnetic with weak antiferromagnetic coupling due to the presence of organic radicals of oxidized ligands and high-spin Ni(II) sites of the missing-linker defects. In addition to providing further insights into the origin of the induced electrical conductivity in 2D MOFs, both pristine and iodine-d...

  • Partial Oxidation-Induced Electrical Conductivity and Paramagnetism in a Ni(II) Tetraaza[14]annulene-Linked Metal Organic Framework
    AMER CHEMICAL SOC, 2019
    Co-Authors: Yi Jiang, Onur Buyukcakir, Xiong Chen, Ming Huang, Won Kyung Seong, Sang Kyu Kwak, Se Hun Joo, Sun Hwa Lee, Jung-woo Yoo
    Abstract:

    © 2019 American Chemical Society.We report the synthesis and characterization of a two-dimensional (2D) conjugated Ni(II) tetraaza[14]annulene-linked metal organic framework (NiTAA-MOF) where NiTAA is a macrocyclic MN4 (M = metal, N = Nitrogen) Compound. The structure of NiTAA-MOF was elucidated by Fourier-transform infrared, X-ray photoemission, and X-ray diffraction spectroscopies, in combination with density functional theory (DFT) calculations. When chemically oxidized by iodine, the insulating bulk NiTAA-MOF (σ < 10-10 S/cm) exhibits an electrical conductivity of 0.01 S/cm at 300 K, demonstrating the vital role of ligand oxidation in the electrical conductivity of 2D MOFs. Magnetization measurements show that iodine-doped NiTAA-MOF is paramagnetic with weak antiferromagnetic coupling due to the presence of organic radicals of oxidized ligands and high-spin Ni(II) sites of the missing-linker defects. In addition to providing further insights into the origin of the induced electrical conductivity in 2D MOFs, both pristine and iodine-doped NiTAA-MOF synthesized in this work could find potential applications in areas such as catalase mimics, catalysis, energy storage, and dynamic nuclear polarization-nuclear magnetic resonance (DNP-NMR