Yeung Research Group at UoB

Compositional inhomogeneity in mixed-metal ZIF-8 analogues

Adam’s work on mixed-metal ZIF-8 analogues is out in Chemical Communications!

We study the structural and thermomechanical effects of cation substitution in the compositional family of metal–organic frameworks Zn_1−xCd_x(mIm)₂ (HmIm = 2-methylimidazole). We find complete miscibility for all compositions x, with evidence of inhomogeneous distributions of Cd and Zn that in turn affect framework aperture characteristics. Using variable-temperature X-ray powder diffraction measurements, we show that Cd substitution drives a threefold reduction in the magnitude of thermal expansion behaviour. We interpret this effect in terms of an increased density of negative thermal expansion modes in the more flexible Cd-rich frameworks.

The paper can be found here and the preprint is available for free on ChemRxiv.

Congratulations Adam!

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Summer students 2018

Welcome to two undergraduate students, who join the group over the summer: Frank Nightingale and Anisha Bahl, who’ll be working on fundamentals of MOF formation and development of public engagement activities, respectively. They’ve already been hard at work, in the lab, on the 3D printer, making crystallographic models and more…!

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Two summer projects available

We’ve secured a grant from Oxford Chemistry’s Public Engagement with Research funds for a paid 6-week* summer project on “Flexible, functional framework materials”. It will involve building interactive models to demonstrate how the crystal structures of materials influence their properties and producing information cards and a short online video about them. Suitable candidates should be undergraduate students with an interest in materials, crystallography and of course public engagement!

In other news, our other summer project, on metal-organic framework formation, is still available! If you’re an undergraduate student interested in functional materials, crystallisation and chemical kinetics this could be for you!

For both the projects above, please send a CV and short statement of interest to Hamish by Sun 22 April. Informal interviews will be held at the beginning of Trinity Term.

*Amended from original version: duration will be 6 weeks.

Papers

Thermodynamics and Kinetics of MOF formation

We’re excited to announce that we’ve got a new paper out– what a start to 2018!

It’s a review of research over the last 20 years on the fundamental factors affecting why certain metal-organic frameworks (MOFs) form the structures that they do. It’s entitled “Thermodynamic and Kinetic Effects in the Crystallization of Metal–Organic Frameworks” and it’s published in the journal Accounts of Chemical Research.

The paper describes how our understanding has grown over the years from simple qualitative observations in the 90’s to detailed, quantitative results provided by computational models and powerful in situ experiments today. The authors, my former supervisor Tony Cheetham, Gregor Kieslich at Munich and Hamish delve into how we’re able to understand not just the structures, but the enthalpic, entropic and kinetic factors that shape each material too.

Take a look at the paper here.