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Confinement of iodine molecules into triple-helical chains within robust metal–organic frameworks

DOI: 10.1021/jacs.7b08748 DOI Help

Authors: Xinran Zhang (University of Manchester) , Ivan Da Silva (ISIS Facility) , Harry G. W. Godfrey (University of Manchester) , Samantha K. Callear (ISIS Facility) , Sergey A. Sapchenko (University of Manchester; Nikolaev Institute of Inorganic Chemistry, Siberian Branch of the Russian Academy of Sciences) , Yongqiang Cheng (Oak Ridge National Laboratory) , Inigo J. Vitorica-yrezabal (University of Manchester) , Mark D. Frogley (Diamond Light Source) , Gianfelice Cinque (Diamond Light Source) , Chiu C. Tang (Diamond Light Source) , Carlotta Giacobbe (European Synchrotron Radiation Facility) , Catherine Dejoie (European Synchrotron Radiation Facility) , Svemir Rudic (ISIS Facility) , Anibal J. Ramirez-cuesta (Oak Ridge National Laboratory) , Melissa A. Denecke (University of Manchester) , Sihai Yang (University of Manchester) , Martin Schroeder (University of Manchester)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Journal Of The American Chemical Society

State: Published (Approved)
Published: October 2017
Diamond Proposal Number(s): 14341 , 14938

Abstract: During the nuclear waste disposal process, radioactive iodine in fission product can be released. The widespread implementation of sustainable nuclear energy thus requires the development of efficient iodine stores that have simultaneously high capacity, stability and more importantly, storage density (and hence minimised system volume). Here, we report high I2 adsorption in a series of robust porous metal-organic materials, MFM-300(M) (M = Al, Sc, Fe, In). MFM-300(Sc) exhibits fully reversible I2 uptake of 1.54 g g-1 and its structure remains completely unperturbed upon inclusion/removal of I2. Direct observation and quantification of the adsorption, binding domains and dynamics of guest I2 molecules within these hosts have been achieved using XPS, TGA-MS, high resolution synchrotron X-ray diffraction, pair distribution function analysis, Raman, terahertz and neutron spectroscopy, coupled with density functional theory modelling. These complimentary techniques reveal a comprehensive understanding on the host-I2 and I2-I2 binding interaction at a molecular level. The initial binding site of I2 in MFM-300(Sc), I2I, is located near the bridging hydroxyl group of the [ScO4(OH)2] moiety [I2I···H–O = 2.263(9) Å] with an occupancy of 0.268. I2II is located interstitially between two phenyl rings of neighbouring ligand molecules [I2II···phenyl ring = 3.378(9) and 4.228(5) Å]. I2II is 4.565(2) Å from the hydroxyl group with an occupancy of 0.208. Significantly, at high I2 loading an unprecedented self-aggregation of I2 molecules into triple-helical chains within the confined nano-voids has been observed at crystallographic resolution, leading to a highly efficient packing of I2 molecules with an exceptional I2 storage density of 3.08 g cm-3 in MFM-300(Sc).

Subject Areas: Chemistry, Materials, Environment

Instruments: B22-Multimode InfraRed imaging And Microspectroscopy , I11-High Resolution Powder Diffraction

Other Facilities: ESRF; ORNL