After pursuing an undergraduate degree in Natural Sciences at the University of Cambridge, specializing in Chemistry, Thomas Bennett obtained his PhD from the same university in 2012, under Professor Anthony Cheetham FRS. He then undertook a three-year Research Fellowship in the Department of Materials Science and Metallurgy at the University of Cambridge, before in 2016, he was awarded a prestigious Royal Society University Research Fellowship, and he now leads the Hybrid Materials Group in the same department. He holds an International Visiting Professorship at the Wuhan University of Technology (China), where his second group is based, along with a visiting Scientist position at CSIRO in Melbourne, Australia.
In 2009 he was awarded an honorary HRH Sheikh Saqr Research Fellowship at the Ras Al Khaimah Center for Advanced Materials (RAK-CAM), United Arab Emirates, and received the inaugural PanAlytical prize for an outstanding contribution to X-ray diffraction in 2013. He delivered the inaugural Otto Schott award at the University of Jena in 2017. His group is internationally leading in the area of non-crystalline metal-organic frameworks, and the work has received attention in Nature Communications, Nature Chemistry, Nature Materials and Chemistry World.
Metal-Organic Framework Glasses: A New Category of Melt Quenched Glasses
*1Thomas D. Bennett, 1Louis Longley, 1Christopher W. Ashling, 1Shichun Li, 1Jingwei Hou,
2David A. Keen, 3Romain Gaillac, 3François-Xavier Coudert
1Department of Materials Science and Metallurgy, University of Cambrdige, UK
2ISIS Facility, Rutherford Appleton Laboratory, Harwell Campus, UK
3Chimie ParisTech, Paris, France
Metal–organic frameworks (MOFs) are a family of chemically diverse materials, consisting of inorganic nodes or ions linked by organic ligands. They have applications in a wide range of fields, covering engineering, physics, chemistry, biology and medicine. Until recently, research has focused almost entirely on crystalline structures, with over 60,000 structures now known. However, now a clear trend is emerging, shifting the emphasis onto disordered states, including ‘defective by design’ crystals, as well as amorphous phases such as glasses.
We have recently shown a subset of metal-organic frameworks (MOFs), called zeolitic imidazolate frameworks (ZIFs), to melt, and quenching of the resultant liquids forms a new category of glass.1 Several structures (e.g. ZIF-4 [Zn(C3H3N2)2]) melt between 400 and 600 °C, and the glasses obtained upon cooling retain the short-range order (i.e. local bonding under 6 Å) present in their crystalline counterparts.2
Here, we introduce the concept of a liquid metal-organic framework,3 and explore the mechanism of melting of ZIF-4, via in-situ pair distribution function measurements and associated Reverse Monte-Carlo modelling, coupled with density functional theory based molecular dynamics calculations. We show that melting proceeds with significant structural retention, due to breakage of only part of the metal coordination sphere. The structure of the liquid phase is characterized, as is the mechanism of vitrification upon cooling. The atomic configuration obtained bears striking similarities to that for aSiO2.
Figure 1. Atomic configuration of a glass of composition Zn(C3H3N2)2. This may be
viewed as a hybrid analogue to silica glass, SiO
1. Bennett, Coudert et al, Nat. Chem., 2017, 9, 11-16.
2. Bennett* et al, Nat. Commun., 2015, 6, 8079.
3. Gaillac, Keen, Beyer, Chapman, Bennett* and Coudert*, Nat. Mater., 2017, 16, 1149-1154.