|dc.description.abstract||Some of the challenges faced when developing novel functional materials, cannot be
resolved without the correct understanding of their structure‐property relationships.
Metal‐organic frameworks (MOFs) constitute a representative example where in-depth
structural knowledge can greatly help improve and optimise their application
into industrially relevant settings. Fortunately, the inherent crystalline nature of
MOFs allows for analysis using the wide range of crystallographic experimental
techniques that are currently available.
This work covers the study of the structural properties of a particular family of MOFs,
which have shown significant potential as molecular sieves and for gas storage. Sc-based
MOFs first attracted attention for their particularly robust and inert nature,
bypassing some of the physical challenges many MOFs have when undergoing
After an initial review of the state of the art in the field of MOFs and the techniques
utilised to analyse their properties, this work then focuses on the mechanical
properties of a series of functionalised and unfunctionalised Sc‐dicarboxylate MOFs.
Using nano‐indentation techniques and high‐pressure crystallography, the hardness
and elasticity of these materials are correlated to their different structural features,
confirming their relative robustness when compared to other MOFs in the literature.
An interesting property of Sc2BDC3 is its selective uptake of CO2 over other fuel-related
gases such as CH4 and CO. In this context, the in situ adsorption
crystallographic analysis of Sc2BDC3 and its amino‐functionalised derivative
Sc2(BDC‐NH2)3 (BDC‐NH2 = 1,4‐amino‐2‐benzenedicarboxylate) is described, as
performed using the gas cell set up of beamline I19 at the Diamond Light Source
synchrotron. This study is the first example of a mixed gas atmosphere experiment
using single‐crystal diffraction, which in conjunction with in silico, adsorption and
breakthrough experiments, provides direct insight into the interactions that drive the
selective behaviour of both frameworks.
Following this, the MOF Sc2BDC3 (BDC = 1,4‐benzenedicarboxylate), is selected as a
case study for branched and unbranched alkane separation. Here, high‐pressure
crystallography shows how these relatively oversized guest molecules, can be forced
at thousands of atmospheres of pressure inside the narrow triangular channels (< 4 Å
diameter) of the framework. It is also possible to resolve the structural changes the
framework undergoes upon uptake of the different guests, as well as locate the
adsorption sites of the hydrocarbons in the pores of Sc2BDC3, which can be then
correlated to the gas adsorption behaviour of the different guests.
To conclude, the high‐pressure inclusion study of both CO2 and CH4 inside Sc2BDC3
shows how combining cryoloading techniques and molecular crystallography for the
first time, can provide improved models of the adsorbed gaseous guests inside
Sc2BDC3. This example not only provides a novel alternative in which to study more
easily the adsorption sites in MOFs via diffraction techniques, but also reveals some
of the interesting structural behaviour MOFs can have in these extreme conditions.||en
|dc.contributor.sponsor||Engineering and Physical Sciences Research Council (EPSRC)||en
|dc.publisher||The University of Edinburgh||en
|dc.relation.hasversion||“In situ Synchrotron IR Microspectroscopy of CO2 Adsorption on Single Crystals of the Functionalized MOF Sc2(BDC‐NH2)3” A. Greenaway, B. Gonzalez‐Santiago, P. M. Donaldson, M. D. Frogley, G. Cinque, J. Sotelo, S. Moggach, E. Shiko, S. Brandani, R. F. Howe and P. A. Wright. Angewandte Chemie International Edition, 2014, 53, 13701‐ 13705.||en
|dc.relation.hasversion||“Mechanical Properties of Zeolitic Metal‐Organic Frameworks: Mechanically Flexible Topologies and Stabilization against Structural Collapse” T. D. Bennet, J. Sotelo, J.‐C. Tan and S. Moggach. CrystEngComm, 2015, 17¸286‐289.||en
|dc.relation.hasversion||“Locating Gases in Porous Materials: Cryogenic Loading of Fuel Related Gases Into a Sc‐based MOF under Extreme Pressures” J. Sotelo, C. H. Woodall, D. R. Allan, E. Gregoryanz, R. T. Howie, K. V. Kamenev, M. R. Probert, P. A. Wright and S. A. Moggach. Angewandte Chemie International Edition, 2015, 54, 13332‐13336.||en
|dc.title||Structural behaviour and adsorption properties of Sc-based metal-organic frameworks||en
|dc.type||Thesis or Dissertation||en
|dc.type.qualificationname||PhD Doctor of Philosophy||en