EXAFS as Powerful Analytical Tool for the Investigation of Organic–Inorganic Hybrid Materials

Gross, Silvia

doi:10.1002/adfm.201000095

Cited by 36 publications

(30 citation statements)

References 173 publications

(188 reference statements)

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“…11,12,64,65,[87][88][89][90][91][92][93][94][95][96][97][98][99][100][101] Conversely, to the best of our knowledge, only Schaate et al 101 have so far been able to reproduce the synthesis of UiO-67. This material has consequently still to be considered as a prototype material, synthesis and framework stability and properties of which have to be checked and confirmed by the scientific community.…”

Section: Resultsmentioning

confidence: 98%

H₂storage in isostructural UiO-67 and UiO-66 MOFs

Chavan

Vitillo

Gianolio

et al. 2012

Phys. Chem. Chem. Phys.

451

356

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The recently discovered UiO-66/67/68 class of isostructural metallorganic frameworks (MOFs) [J. H. Cavka et al. J. Am. Chem. Soc., 2008, 130, 13850] has attracted great interest because of its remarkable stability at high temperatures, high pressures and in the presence of different solvents, acids and bases [L. Valenzano et al. Chem. Mater., 2011, 23, 1700]. UiO-66 is obtained by connecting Zr(6)O(4)(OH)(4) inorganic cornerstones with 1,4-benzene-dicarboxylate (BDC) as linker resulting in a cubic MOF, which has already been successfully reproduced in several laboratories. Here we report the first complete structural, vibrational and electronic characterization of the isostructural UiO-67 material, obtained using the longer 4,4'-biphenyl-dicarboxylate (BPDC) linker, by combining laboratory XRPD, Zr K-edge EXAFS, TGA, FTIR, and UV-Vis studies. Comparison between experimental and periodic calculations performed at the B3LYP level of theory allows a full understanding of the structural, vibrational and electronic properties of the material. Both materials have been tested for molecular hydrogen storage at high pressures and at liquid nitrogen temperature. In this regard, the use of a longer ligand has a double benefit: (i) it reduces the density of the material and (ii) it increases the Langmuir surface area from 1281 to 2483 m(2) g(-1) and the micropore volume from 0.43 to 0.85 cm(3) g(-1). As a consequence, the H(2) uptake at 38 bar and 77 K increases from 2.4 mass% for UiO-66 up to 4.6 mass% for the new UiO-67 material. This value is among the highest values reported so far but is lower than those reported for MIL-101, IRMOF-20 and MOF-177 under similar pressure and temperature conditions (6.1, 6.2 and 7.0 mass%, respectively) [A. G. Wong-Foy et al. J. Am. Chem. Soc., 2006, 128, 3494; M. Dinca and J. R. Long. Angew. Chem., Int. Ed., 2008, 47, 6766]. Nevertheless the remarkable chemical and thermal stability of UiO-67 and the absence of Cr in its structure would make this material competitive.

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Section: Resultsmentioning

confidence: 98%

H₂storage in isostructural UiO-67 and UiO-66 MOFs

Chavan

Vitillo

Gianolio

et al. 2012

Phys. Chem. Chem. Phys.

451

356

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“…X-ray spectroscopy [1][2][3] is a powerful spectroscopic tool for the elucidation of structural and electronic properties of materials [4][5][6] and (bio-)molecular systems [7][8][9]. X-ray absorption spectroscopy (XAS) probes the excitation of core electrons.…”

Section: Introductionmentioning

confidence: 99%

Origin-independent calculation of quadrupole intensities in X-ray spectroscopy

Bernadotte

Atkins

Jacob

2012

The Journal of Chemical Physics

147

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For electronic excitations in the ultraviolet and visible range of the electromagnetic spectrum, the intensities are usually calculated within the dipole approximation, which assumes that the oscillating electric field is constant over the length scale of the transition. For the short wavelengths used in hard X-ray spectroscopy, the dipole approximation may not be adequate. In particular, for metal K-edge X-ray absorption spectroscopy (XAS), it becomes necessary to include higher-order contributions. In quantum-chemical approaches to X-ray spectroscopy, these socalled quadrupole intensities have so far been calculated by including contributions depending on the square of the electric-quadrupole and magnetic-dipole transition moments. However, the resulting quadrupole intensities depend on the choice of the origin of the coordinate system. Here, we show that for obtaining an originindependent theory, one has to include all contributions that are of the same order in the wave vector consistently. This leads to two additional contributions depending on products of the electric-dipole andelectric-octupole and of the electric-dipole and magnetic-quadrupole transition moments, respectively. We have implemented such an origin-independent calculation of quadrupole intensities in XAS within timedependent density-functional theory, and demonstrate its usefulness for the calculation of metal and ligand K-edge XAS spectra of transition metal complexes.2

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“…5(a)) give qualitative information about the Zr–O polyhedra or the nearest O to the Zr3031. The shape of the white line reflects the number of O atoms in the polyhedra.…”

Section: Resultsmentioning

confidence: 99%

Hybrid Cluster Precursors of the LaZrO Insulator for Transistors: Properties of High-Temperature-Processed Films and Structures of Solutions, Gels and Solids

Zhu

Hirose

et al. 2016

Sci Rep

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In the solution processing of oxide electronics, the structure of metal–organic precursors in solution and their effect on processability and on the final structure and properties of the oxide have rarely been studied. We have observed that hybrid clusters, having inorganic cores coordinated by organic ligands, are the typical form of metal–organic precursor structures. For insulating ternary LaZrO, improved synthesis of the cluster precursor under solvothermal conditions led to low-temperature deposition of the film at 200 °C, as we will report in another paper. In the current paper, we first briefly show that solvothermal synthesis of the precursor resulted in significantly improved insulating properties (e.g., two orders lower leakage current) of high-temperature-annealed films, and then focus on the structural analysis of the cluster precursors and annealed solids and relate the results to the significant improvement of properties by solvothermal treatment of solutions. A change in the cluster core toward structural unification was brought about by solvothermal treatment, resulting in higher uniformity and higher stability of clusters. The final structure of the material maintained the features of the core structure in solution, even after annealing at high temperatures. These results demonstrate the key role played by designing cluster structure in solution.

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EXAFS as Powerful Analytical Tool for the Investigation of Organic–Inorganic Hybrid Materials

Cited by 36 publications

References 173 publications

H₂storage in isostructural UiO-67 and UiO-66 MOFs

H₂storage in isostructural UiO-67 and UiO-66 MOFs

Origin-independent calculation of quadrupole intensities in X-ray spectroscopy

Hybrid Cluster Precursors of the LaZrO Insulator for Transistors: Properties of High-Temperature-Processed Films and Structures of Solutions, Gels and Solids

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EXAFS as Powerful Analytical Tool for the Investigation of Organic–Inorganic Hybrid Materials

Cited by 36 publications

References 173 publications

H2storage in isostructural UiO-67 and UiO-66 MOFs

H2storage in isostructural UiO-67 and UiO-66 MOFs

Origin-independent calculation of quadrupole intensities in X-ray spectroscopy

Hybrid Cluster Precursors of the LaZrO Insulator for Transistors: Properties of High-Temperature-Processed Films and Structures of Solutions, Gels and Solids

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H₂storage in isostructural UiO-67 and UiO-66 MOFs

H₂storage in isostructural UiO-67 and UiO-66 MOFs