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Combined study of structural properties on metal-organic frameworks with same topology but different linkers or metal

DOI: 10.1088/1742-6596/430/1/012134 DOI Help

Authors: D. Gianolio (Diamond Light Source) , J. G. Vitillo (University of Turin) , B. Civalleri (University of Turin) , S. Bordiga (University of Turin) , U. Olsbye (University of Oslo) , K. P. Lillerud (University of Oslo) , L. Valenzano (Michigan Technological University) , C. Lamberti (University of Turin)
Co-authored by industrial partner: No

Type: Conference Paper
Conference: 15th International Conference on X-ray Absorption Fine Structure (XAFS15)
Peer Reviewed: No

State: Published (Approved)
Published: April 2013

Open Access Open Access

Abstract: The recently discovered UiO-66/67/68 class of isostructural metallorganic frameworks (MOFs) [2008 J. Am. Chem. Soc. 130 13850] has attracted great interest because of its remarkable stability at high temperatures, high pressures and in presence of different solvents acids and bases [2011 Chem. Mater. 23 1700]. UiO-66 is obtained connecting Zr6O4(OH)4 inorganic cornerstones with 1,4-benzene-dicarboxylate (BDC) linkers, while for the isostructural UiO-67, the longer 4,4' biphenyl-dicarboxylate (BPDC) is used as linker [2012 Phys. Chem. Chem. Phys. 14 1614]. Hf-UiO-66 is built with the same linker of UiO-66 but, in this case, Hf6O4(OH)4 blocks substitute the Zr6O4(OH)4 ones [2012, Phys. Rev. B 86 125429]. In all cases isostructural cubic MOFs are obtained. Here we report a systematic EXAFS investigation of UiO-66 and UiO-67 (at Zr L3-edge) and of Hf-UiO-66 (at Hf L3-edge) before and after the removal of solvent in their pores, needed to make the channel volume available. The study reveals that, for the three systems, the perfect M6O4(OH)4 (M = Zr or Hf) octahedron forming the cornerstones of the as prepared material undergoes a remarkable local rearrangement into a distorted M6O6 octahedron, with the loss of two water molecules under the desolvation process. Notwithstanding the high crystallinity of the materials, this rearrangement, moving M atoms from 8-fold to 7-fold coordination and distorting the M-M distance of the octahedron side by more than 0.2 Å, escape XRPD detection (because not ordered on the long range scale) but is clearly observed by EXAFS owing to its local sensitivity

Journal Keywords: Absorption Spectroscopy; Benzene; Biphenyl; Detection; Fastening; Fine Structure; Organometallic Compounds; Pressure Range Mega Pa 10-100; Sensitivity; Solvents; Stability; Temperature Range 0400-1000 K; Topology; X-Ray Spectroscopy

Subject Areas: Chemistry, Materials

Facility: BM29 at ESRF

Added On: 29/04/2013 09:40


Discipline Tags:

Chemistry Materials Science Metal-Organic Frameworks Metallurgy Organometallic Chemistry

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