Dr Timothy Easun
Royal Society University Research Fellow
Dr Easun's research targets the use of photochemistry to control molecular flow in microporous materials in order to make functional nanofluidic devices. This involves the functionalisation of crystalline porous materials, specifically using thermally and photochemically active components to control framework properties and direct guest uptake and release.
The key concepts that underpin this research are those of supramolecular photochemistry, nanofluidics, time-resolved spectroscopies, photocrystallography and microporous materials with nanoscale pores and channels.
The work is focussed on two main areas: the surface modification of metal-organic framework (MOF) crystals to photogate access to and from their pores and the design of new MOF linkers that change shape on photoirradiation. These projects require the design, synthesis and characterisation of photoactive molecules, studied by ultrafast time-resolved and spatially-resolved spectroscopies, coupled with new and emerging photocrystallographic techniques that allow us to understand in detail the behaviour of these molecules in single crystals.
PNAS, 2017, 114, 12, 3056-3061: "Tailoring porosity and rotational dynamics in a series of octacarboxylate metal-organic frameworks".
J. Am.Chem. Soc., 2016, 138 (20), 6352-6355: “Proton Conduction in a Phosphonate-Based Metal–Organic Framework Mediated by Intrinsic “Free Diffusion inside a Sphere”
J. Mater. Chem A, 2016, 4, 6714: “The lighter side of MOFs: structurally photoresponsive metal–organic frameworks”. [Invited review for 2016 “Emerging Investigators” special issue]
Chemical Science, 2014, 5, 539: “Modification of Coordination Networks Through a Photoinduced Charge Transfer Process”
Msci Chemistry (with ERASMUS semester at the Università degli Studi di Sassari, Italy), University of Nottingham (1998-2002); PhD, University of Sheffield (2003-2007, Prof. Mike Ward); Postdoctoral Research Fellow, University of Nottingham (2007-2010, Prof. Mike George); Inorganic Teaching Fellow, University of Nottingham (2010-2011); Senior Research Officer, University of Nottingham (2011-2015, Prof. Martin Schröder, Dean of the Faculty of Science). Appointed Cardiff University Research Fellow 2015 and awarded Royal Society University Research Fellowship in the same year.
Member of the Royal Society of Chemistry, the American Chemical Society, the Infrared & Raman Discussion Group, the British Crystallographic Association, and Early Career Panel Member of the EPSRC Directed Assembly Grand Challenge Network.
The ultimate goal of my work is to combine nanofluidics and metal-organic frameworks (MOFs) with photogated control of molecular flow to create a new platform technology for the development of nanofluidic devices.
A key obstacle in the field of nanofluidics is the lack of well-defined nanostructured materials to study. This has major implications in nanofluidic device design and in our fundamental understanding of molecular behaviour in nanoscale confined spaces.
MOFs are porous crystalline frameworks with applications in the adsorption and separation of a wide range of guest species. Particular interest has developed in the last decade in their potential to store and separate commercially important gases, such as H2, CO2 and CH4. Two key challenges in the field are (i) understanding guest diffusion and (ii) characterising defects in single crystals, both essential to develop MOFs for their primary applications as rapid-response guest storage media.
Our research exploits MOFs to serve three purposes: (a) enabling nanofluidic simulation and experiment to be matched up to enhance fundamental understanding of nano-confined fluid behaviour that can be applied to device design; (b) affording a detailed understanding of the defects in MOFs that impacts their commercial applicability; and (c) opening up new uses for MOFs beyond the traditional and well-studied areas of gas storage and separations.
The challenges of characterising guest diffusion in MOF materials and providing nanoscale ordered architectures for nanofluidic devices are addressed by a two-pronged approach: (i) surface coating of MOFs with photoresponsive molecules to act as gates to the pores, controlling ingress and egress of guests, and (ii) incorporating photoresponsive linkers in MOFs that enable spatio-temporally controlled crystal structure change on photoirradiation. The flow of guests through these materials can be monitored using light microscopies and controlled using laser-induced structural change to block/unblock the MOF pores, ultimately with 3D spatial resolution.