Applying Long-lived Metastable States with Switchable Functionality via Kinetic Control of Molecular Assembly - a Programme in Functional Materials

Lead Research Organisation: University of Bath
Department Name: Chemistry

Abstract

One of the most important current areas in chemistry is developing new materials that are able to respond rapidly and
reliably to changes in local environment, and send out signals that let us know what is happening. These "smart" materials can be used as sensors in a wide range of situations and are used in many aspects of modern life, from press-on patches to take a patient's temperature to solid-state electronic components in modern televisions. The clever chemistry used to develop such materials can help make materials with just the right property for the right situation - they can be made tuneable. The chemist aims to produce new, smart, responsive materials to be manufactured into useful devices for real applications. To produce new, better, more energy efficient materials that can benefit UK manufacturing and keep the UK at the forefront of technological developments, we need to find new ways of controlling the properties and functions of molecules to produce "even smarter" materials. This proposal aims to do just this, using a new way of tuning the properties of materials.
Most smart materials operate in an equilibrium state, while most complex systems, such as animals and humans, operate
in non-equilibrium states that are much more responsive to small changes in environment and can thus function in more
complex ways; indeed, if the human race operated in equilibrium, life would cease to exist as we know it! We need stimuli
to keep us alive we wish to take inspiration from ourselves in developing a new generation of smart materials, by applying
the ideas of "non-equilibrium" states to the development and operation of new materials. These will operate in different
ways giving access to new properties and functions.
Our new approach to designing new materials that operate in non-equilibrium conditions, uses "metastable" or excited
states - this means that we stimulate the material, for example by a light pulse, and by doing so we change the way in
which the chemical structure of that material delivers its properties. Effectively using excited states we can change the
behaviour of the electrons and hence the effect of the chemistry of a material without apparently changing its chemistry at all! Many current switchable smart materials must include regions of a different chemical or physical composition - these defects are very important for giving a material its properties, but produce a heterogeneous material - a good example is the "metamaterials" which physicists are developing. We will be able to introduce the same tuneable function but in chemically homogeneous materials, with real advantages for controlling their stability and performance.
To achieve this, we have to make significant advances across a range of areas, including designing the chemistry of
metastable switchable materials, generating excited states that give the desired change of property, controlling these
"metastable-excited states" and eventually to build these into useful devices for applications. Our proposal will allow us to develop ways of controlling the properties and functions of these metastable materials in ways that are not possible
currently.
There are many possible applications for these new materials including more efficient conductors and more miniaturisation
of devices that rely on electronics. We can also envisage engineering thin films that will provide each of the colours of the spectrum by simply changing the input voltage, allowing smart paints or smart fabrics whose colour could be chosen to suit mood or environment. We can also develop "active membranes" whose mechanical properties can be actively tuned, which will be useful in medicine and energy applications. In the longer term there is the prospect of developing
materials with a negative refractive index, whose special properties would mean that by switching on and off an electric
current, objects will apparently disappear and reappear!

Planned Impact

This Programme will develop the fundamental underpinning research for a new family of functional materials. Scientifically, we will tackle the challenges of designing and making such materials, for which we must fully understand and control the generation and lifetime of the required metastable states. This will be tackled by the assembled diverse team at Bath and augmented by our many collaborative and consortia links. We will develop enhanced methods in synthesis, self-assembly, modelling and characterisation, that will have impact across the community in both science and technology, in addition to the potential impact of the materials themselves.

Initial Impact will be within the academic community, for whom our development of new methodologies, advanced experimental and computational techniques and, in essence, a whole new class of potentially functional materials will be of high value and interest. Without a doubt our early stage development within the Programme are at the fundamental end of our proposed range of research investigations, so this academic impact is likely to accrue very early in the Programme. Conceptually and practically, our harnessing of the untapped potential of long-lived metastable states for the production of functional chemically-inspired materials is moving onto new ground, and we expect this to influence the thinking and approach across the science disciplines, moving beyond chemists to physicists working in related fields (particularly metamaterials and other defect materials), materials scientists interested in functionality, and engineers interested in building smart devices into a range of production environments. Our Programme maps heavily onto important signposted (Directed Assembly, Frontier Manufacturing) and Grand Challenge areas (Healthcare (sensing, optical switching, smart membranes), Energy (new materials types, smart functional membrane technology), Environment (remediation, gas separation), Manufacturing (new materials types for low energy devices, bottom-up approaches to manufacturing) and Global Security (sensing) and so will help the academic community in engaging with these Challenges and recognising the diversity of approach that can be rewarding in meeting them.

Harnessing the power of metastable states in the way proposed is unprecedented, and the creation of such a radical approach to functionality will have potentially massive applied impacts in the medium to longer term. The developed materials will have applications in optics (for example by allowing tuneable refractive index with applications such as the invisibility cloak), pigments (offering flexibly tuneable and switchable colours), active membranes (gas separation, environmental remediation), sensing, etc. We will make leading-edge developments in an area where the UK is the potential world-leader and deliver real applications that will cement this - making UK the port-of-call for potential investment in basic R&D in these metastable materials.

On the slightly longer timescale our links with self-assembly and manufacturing offers the potential for cost-effective, optimised, materials production, while those with device manufacturers offer the potential to produce real device spin-offs from the programme. We will engage fully with industrial partners as the Programme evolves, moving from our initial "Cloud" model to more concrete interactions as our discovery programme feeds into materials development. We have a strong track record of engagement with industry - from SMEs to multinationals - and will benefit also from routes enabled by the University of Bath including specific Knowledge Transfer funding, KTP opportunities and support from the Research Office in exploring IP protection and commercialisation options.

Our research workers will receive training in a highly interdisciplinary, outward-looking, collaborative environment with extensive external links.

Publications

10 25 50

 
Description Progress and Achievements End of Grant Success Criteria
Transition Metal Linkage Isomers
• Near room temperature fully reversible switching in a Pd(II) nitro linkage isomer (through design) (See CrystEngComm., 2016,18, 4180 & CrystEngComm., 2017, 19, 6297)
• Developed understanding of kinetics of linkage isomer switching, with energies evaluated for the processes, and validated prediction of half-lives of the excited states above the metastable limit. This effectively provides precise control of the lifetimes of these materials at a given temperature allowing for the design of a colour changing switch at a prescribed temperature. (See PCCP, 2018, 20, 5874).
• Development of pulsed LED-based techniques for photoactivation to determine the dynamic structures of linkage isomers on a millisecond-second timescales. The techniques have been implemented successfully on beamline I19 at Diamond, and analysis of the Pd systems with 40s lifetimes at 260 K were achieved in January 2018 and in March we were able to obtain data with 10s lifetimes.
Platinum (II) Pincer Complexes
• Development of fast (sub-second) colour changing Pt(II) N-C-N pincer complexes for specific detection of 1000 ppm of water (yellow to red colour change) and methanol (yellow to blue colour change) (no colour change for other VOCs). (See Nature Communications, 2017, 8, 1800).
• Effective incorporation of the Pt(II) N-C-N pincers into PIMs without loss of sensitivity to water and methanol, and without deterioration of the embedded material after 3 weeks of continuous testing. (See Nature Communications, 2017, 8, 1800).
• Collaboration with Carl Sangan's group in Mechanical Engineering to use the Pt pincers as water detection materials in jet engines. (International Journal of Heat and Mass Transfer 127 (2018) 437-446).
• Platinum (II) N-C-N acetato colour changing complex with faster response time than N-C-N cyanide pincer that is reactive methanol and dichloromethane.
• Systematic development of a new class of terpyridine Pt(II) pincer complexes with similar colour-changing properties to those of the previously discovered N-C-N pincers.
• Synthesis of new N-C-N pincer photoswitches through a combination of experimental and computational design.
• New platinum(II) pincers that show pH switching.
Organic Thermochromics
• Development of the understanding of the origin of colour in the classes of themochromics (combined experimental and computational study) (CrystEngComm 2019, accepted)
• Extended spectroscopic investigations around the phase changes.
• Development of crystallization techniques in flow to control particle size and reaction scale up.
• Embedding thermochromics in a polymer membrane.
Computational Studies
• Have underpinned all the materials discovery and development projects.
• Developed new lattice dynamics calculations of relevance to time resolved studies and nanoscale structural analysis.
• Prediction of thermodynamic stability in molecular and array materials. (See APL Materials, 2017, 5, 036101 and J Phys Chem C, 2017, 121, 6446).
• Spectroscopic simulations for all classes of materials.
MOF Materials
• Development of molecular cages (MOFs) for the successful incorporation of switchable materials. Switching observed under photoactivation or by the addition of gases and followed dynamically by crystallography. (See Inorg Chem submitted).
• Demonstrated that MOFs can be effective hosts for reactions, allowing 'solution-like' behaviour in the solid state.
• Developments in post-synthetic modification to modify cages for incorporation of photoactive guests.
• Development of new host materials with diotopic ligands. (See CrystEngComm, 2017, 19, 5549)
Helicenes
• Chiroptical Helicene Switch as a Fractal Dimension Switcher through self-assembly of helicenes - the first molecular switch based on switching fractal dimension?
• Development of LC Skyrmions - Topological Quasiparticles
Towards Devices
• Successful developments of synthesis and crystallisation under flow conditions. Much improved control of particle size (tested on switchable complexes).
• Development and use of multi-platform flow synthesis reactors (in collaboration with Vapourtec Ltd).
• Development of novel microporous materials for membrane technologies.
• Development of helicenes for optical up-conversion in nano-shells with sensor technologies.
• Development of microporous electroluminescent devices for novel sensor systems.
• Achieved platinum-group metal-based pincer complexes embedded in microporous materials for fast colour responses to gas and liquid chemicals.
• Moving forward to electroluminescence studies on some of the MOF and polymer materials.
Exploitation Route Industry is already interested in using the new materials that we are developing in devices for chemical and light sensing applications. Carl Sangan's group in MEchanical Engineering, at Bath is using our materials as water vapour sensors in jet engine test beds.
Sectors Aerospace, Defence and Marine,Agriculture, Food and Drink,Chemicals,Electronics,Energy,Environment,Healthcare

URL http://www.metastable-materials.org.uk/
 
Description Through this programme we have developed several new classes of material that have novel sensing properties, showing color changes when exposed to light or volatile organic reagents. We are now in discussion with industry to develop these materials as coatings for real-world applications.
First Year Of Impact 2016
Sector Education,Electronics,Energy,Environment
Impact Types Societal,Economic

 
Description Programme Grant
Amount £3,240,870 (GBP)
Funding ID EP/K004956/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start 11/2012 
End 10/2017
 
Description Responsive mode
Amount £465,600 (GBP)
Funding ID EP/P001548/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Academic/University
Country United Kingdom
Start 11/2016 
End 11/2019
 
Title Development of non-ambient crystallographic methods for high pressure studies 
Description During this project we have helped to design and implement gas cells and high pressure cells on Beamline I19 at the Diamond Light Source to study transformations of a range of materials under moderate to high pressure. 
Type Of Material Improvements to research infrastructure 
Year Produced 2013 
Provided To Others? Yes  
Impact The new cells are now in regular use on Beamline I19 for the whole user community. 
 
Title Dynamic methods for Single Crystal X-ray Crystallography and XAFS using synchrotron radiation 
Description During the project we have developed time resolved methods (between nanoseconds and milliseconds) for determining the structures of molecules in the solid state (X-ray and EXAFS) and in solution (XAFS) that have short lifetimes. These materials include charge transfer complexes and catalysts. 
Type Of Material Improvements to research infrastructure 
Year Produced 2015 
Provided To Others? Yes  
Impact We have developed the HATRX method for determining the structures of molecules with short lifetimes (micro and milliseconds) and this methodology is now available to academic users on the single crystal beamline, I 19, at the Diamond synchrotron, and is also being used at the synchrotron in Hamburg. 
 
Title Methods for determining the structures of materials that are metastable or have short lifetimes in the solid state using photocrystallographic methods 
Description We have developed single-crystal X-ray crystallographic methods for determining the structures of metastable materials using photocrystallographic methods. These methods have been adopted by other groups and photocrystallography is now a growing topic. 
Type Of Material Improvements to research infrastructure 
Year Produced 2010 
Provided To Others? Yes  
Impact We have established the structures of a range of coordination complexes that show linkage isomerism under photoactivation. The use of LEDs to photoactivate the materials is now in teh public domain and the methodology has been adopted by a number of research groups. 
 
Title Time resolved spectroscopic methods 
Description During this project we have developed time-resolved IR methods for studying the dynamics of inorganic and metallo-organic materials in the solid state. 
Type Of Material Improvements to research infrastructure 
Year Produced 2014 
Provided To Others? Yes  
Impact These methods are now available to other users of the Central Laser facility 
 
Title Data for "A rapidly-reversible absorptive and emissive vapochromic Pt(II) pincer-based chemical sensor" 
Description Data to accompany the article "A rapidly-reversible absorptive and emissive vapochromic Pt(II) pincer-based chemical sensor". This dataset contains data from the computational modelling carried out as part of this study, including optimised structures and simulated optical-absorption spectra. 
Type Of Material Database/Collection of data 
Year Produced 2017 
Provided To Others? Yes  
 
Title Data for "Chemical and Lattice Stability of the Tin Sulfides" 
Description Raw data to accompany the article "Chemical and Lattice Stability of the Tin Sulfides". This dataset includes the optimised structures, force constants, phonon dispersions and density of states curves, and thermodynamic functions for the seven compounds studied in this work. 
Type Of Material Database/Collection of data 
Year Produced 2017 
Provided To Others? Yes  
 
Title Data for "Crystalline adducts of the Lawsone molecule (2-hydroxy-1,4-naphthaquinone): optical properties and computational modelling" 
Description Raw data to accompany the publication "Crystalline adducts of the Lawsone molecule (2-hydroxy-1,4-naphthaquinone): optical properties and computational modelling". 
Type Of Material Database/Collection of data 
Year Produced 2015 
Provided To Others? Yes  
 
Title Data for "Estimation of semiconductor-like pigment concentrations in paint mixtures and their differentiation from paint layers using first-derivative reflectance spectra" 
Description This repository contains key raw data to accompany the article "Estimation of semiconductor-like pigment concentrations in paint mixtures and their differentiation from paint layers using first-derivative reflectance spectra". The repository includes a complete set of reflectance spectra recorded from the paint samples prepared for this work, plus the optimised structures and electronic density-of-states and band-dispersion curves obtained from complementary modelling studies on the three coloured pigments investigated, viz. alpha-HgS (vermillion), tetragonal Pb3O4 (red lead) and SnPb2O4 (lead-tin yellow). Abstract of the publication: Identification of the techniques employed by artists, e.g. mixing and layering of paints, if used together with information about their colour palette and style, can help to attribute works of art with more confidence. In this study, we show how the pigment composition in binary paint mixtures can be quantified using optical-reflectance spectroscopy, by analysis of the peak features corresponding to colour-transition edges in the first-derivative spectra. This technique is found to be more robust than a number of other spectral-analysis methods, which can suffer due to shifts in the transition edges in mixed paints compared to those observed in spectra of pure ones. Our method also provides a means of distinguishing paint mixtures from layering in some cases. The spectroscopy also shows the presence of multiple electronic transitions, accessible within a narrow energy range, to be a common feature of many coloured pigments, which electronic-structure calculations attribute to shallow band edges. We also demonstrate the successful application of the reflectance-analysis technique to painted areas on a selection of medieval illuminated manuscripts. 
Type Of Material Database/Collection of data 
Year Produced 2016 
Provided To Others? Yes  
 
Title Data for "Metastable cubic tin sulfide: a novel phonon-stable chiral semiconductor" 
Description Raw data to accompany the article "Metastable cubic tin sulfide: a novel phonon-stable chiral semiconductor". This dataset contains the optimised crystal structure of pi-cubic SnS, data from the lattice-dynamics calculations including the calculated force constants and phonon spectra, data from the electronic-structure calculations, and the simulated frequency-dependent dielectric function and derived properties. 
Type Of Material Database/Collection of data 
Year Produced 2017 
Provided To Others? Yes  
 
Title Data for "Phonon anharmonicity, lifetimes, and thermal transport in CH3NH3PbI3 from many-body perturbation theory" 
Description Data to accompany the article "Phonon anharmonicity, lifetimes, and thermal transport in CH3NH3PbI3 from many-body perturbation theory". The data includes a set of input files for the Vienna Ab initio Simulation Package (VASP) electronic-structure code, together with input and output files for the Phonopy and Phono3py packages used to set up and post-process the lattice-dynamics calculations. 
Type Of Material Database/Collection of data 
Year Produced 2016 
Provided To Others? Yes  
 
Title Data for "Solid-state chemistry of glassy antimony oxides" 
Description Data to accompany the article "Solid-state chemistry of glassy antimony oxides". 
Type Of Material Database/Collection of data 
Year Produced 2015 
Provided To Others? Yes  
 
Title Data for "Sulfamerazine: Understanding the Influence of Slip Planes in the Polymorphic Phase Transformation through X-Ray Crystallographic Studies and ab Initio Lattice Dynamics" 
Description Raw data to accompany the paper "Sulfamerazine: Understanding the influence of slip-planes in the polymorphic phase transformation through X-ray crystallographic studies and ab initio lattice dynamics". 
Type Of Material Database/Collection of data 
Year Produced 2015 
Provided To Others? Yes  
 
Title Data for "Suppression of lattice thermal conductivity by mass-conserving cation mutation in multi-component semiconductors" 
Description In semiconductors almost all heat is conducted by phonons (lattice vibrations), which is limited by their quasi-particle lifetimes. Phonon-phonon interactions represent scattering mechanisms that produce thermal resistance. In thermoelectric materials, this resistance due to anharmonicity should be maximised for optimal performance. We use a first-principles lattice-dynamics approach to explore the changes in lattice dynamics across an isostructural series where the average atomic mass is conserved: ZnS to CuGaS2 to Cu2ZnGeS4. Our results demonstrate an enhancement of phonon interactions in the multernary materials and confirm that lattice thermal conductivity can be controlled independently of the average mass and local coordination environments. 
Type Of Material Database/Collection of data 
Year Produced 2016 
Provided To Others? Yes  
 
Title Data for "The Impact of the Alkyne Substitution Pattern and Metallation on the Photo-isomerization of Azobenzene-based Platinum(II) Di-ynes and Poly-ynes" 
Description Data from the computational modelling described in the article "The Impact of the Alkyne Substitution Pattern and Metallation on the Photo-isomerization of Azobenzene-based Platinum(II) Di-ynes and Poly-ynes". Includes optimised molecular structures, vibrational frequencies, electronic excitation level, simulated infrared (IR) and absorption spectra, and assignments of the electronic transitions. 
Type Of Material Database/Collection of data 
Year Produced 2016 
Provided To Others? Yes  
 
Title Data for Ab Initio Molecular-Dynamics Simulation of Neuromorphic Computing in Phase-Change Memory Materials 
Description Raw data to accompany the article Ab Initio Molecular-Dynamics Simulation of Neuromorphic Computing in Phase-Change Memory Materials. 
Type Of Material Database/Collection of data 
Year Produced 2015 
Provided To Others? Yes  
 
Title Data to accompany the article "Anion···p interactions and metastability: structural transformations in a silver-pyrazine network" 
Description This dataset contains data from the computational modelling studies performed in the above article, viz. the optimised structures of the three compounds examined and their calculated dielectric properties. 
Type Of Material Database/Collection of data 
Year Produced 2017 
Provided To Others? Yes  
 
Title Data to accompany the article "Lattice dynamics of the tin sulphides SnS2, SnS and Sn2S3: vibrational spectra and thermal transport" 
Description This repository contains key raw data from the calculations performed in the manuscript, including the optimised structures, data from the lattice-dynamics calculations, the simulated spectra and the thermal-conductivity tensors. 
Type Of Material Database/Collection of data 
Year Produced 2017 
Provided To Others? Yes  
 
Title Dataset for "Systematic approaches towards template-free synthesis of EMT-type zeolites" 
Description This dataset contains powder X-ray diffraction data, scanning electron microscopy (SEM) images and solid state nuclear magnetic resonance (NMR) spectroscopy data (29-Si, 27-Al and 23-Na nuclei), used in the article 'Systematic approaches towards template-free synthesis of EMT-type zeolites'. Herein, research is performed to attempt to synthesise EMT-type zeolites without organic templates, and the influence of the crystallisation process on the amount of organic template is probed. The powder X-ray diffraction data were used to index and identify the structure of the relevant zeolite samples. The SEM images were used to characterise the morphology and size of the crystals/particles produced using the different synthesis batch compositions used in the article. The NMR data of the 29-Si nuclei was used to determine the Si/Al ratio of the relevant samples, and the 27-Al and 23-Na nuclei were used to determine the different environments of these two nuclei in the different samples produced. 
Type Of Material Database/Collection of data 
Year Produced 2018 
Provided To Others? Yes  
 
Description Dynamic Structural Science Workshop 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact A 3 day workshop on the latest developments in dynamic structural science covering time resolved experiments across the life and physical sciences involving XFELS, synchrotrons and lasers. It included 16 talks from international experts in the field. A book of the lectures will be published by Wiley in late 2017.
Year(s) Of Engagement Activity 2016