Imperial College London

Professor Tom Welton

Faculty of Natural SciencesDepartment of Chemistry

Professor of Sustainable Chemistry
 
 
 
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Contact

 

+44 (0)20 7594 5763t.welton Website

 
 
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Location

 

601AMolecular Sciences Research HubWhite City Campus

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Summary

 

Publications

Publication Type
Year
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255 results found

Dobre A, Koutsoukos S, Philippi F, Rauber D, Kay CWM, Palumbo O, Roessler MM, Welton Tet al., 2024, Understanding the effects of targeted modifications on the 1 : 2 Choline And GEranate structure., Phys Chem Chem Phys, Vol: 26, Pages: 8858-8872

1 : 2 Choline-and-geranate (CAGE) is an ionic liquid (IL) widely studied for its biomedical applications. However, both its industrial-scale preparation and its long-term storage are problematic so finding more suitable candidates which retain its advantageous properties is crucial. As a first step towards this we have conducted a targeted modification study to understand the effects of specific functional groups on the properties of CAGE. 1 : 2 Choline-and-octanoate and 1 : 2 butyltrimethylammonium-and-octanoate were synthesised and their thermal and rheological properties examined in comparison to those of CAGE. Using differential scanning calorimetry and polarising microscopy, the model compound was found to be an isotropic liquid, while the analogues were room-temperature liquid-crystals which transition to isotropic liquids upon heating. Dynamic mechanical analysis showed that the thermal behaviour of the studied systems was even more complex, with the ILs also undergoing a thermally-activated relaxation process. Furthermore, we have used electron paramagnetic resonance (EPR) spectroscopy, along with a variety of spin probes with different functional groups, in order to understand the chemical environment experienced by solutes in each system. The EPR spectra indicate that the radicals experience two distinct environments (polar and nonpolar) in the liquid-crystalline phase, but only one average environment in the isotropic phase. The liquid-crystalline phase experiments also showed that the relative populations of the two domains depend on the nature of the solutes, with polar or strongly hydrogen-bonding solutes preferring the polar domain. For charged solutes, the EPR spectra showed line-broadening, suggesting that their ionic nature leads to complex, unresolved interactions.

Journal article

Welton T, 2023, Reflecting on the successes of the first full year of RSC Sustainability, RSC Sustainability, Vol: 2, Pages: 9-10

Journal article

Rauber D, Philippi F, Morgenstern B, Zapp J, Kuttich B, Kraus T, Welton T, Hempelmann R, Kay CWMet al., 2023, Dynamics, cation conformation and rotamers in guanidinium ionic liquids with ether groups, Journal of Ionic Liquids, Vol: 3

Ionic liquids are modern materials with a broad range of applications, including electrochemical devices, the exploitation of sustainable resources and chemical processing. Expanding the chemical space to include novel ion classes allows for the elucidation of novel structure-property relationships and fine tuning for specific applications. We prepared a set of ionic liquids based on the sparsely investigated pentamethyl guanidinium cation with a 2-ethoxy-ethyl side chain in combination with a series of frequently used anions. The resulting properties are compared to a cation with a pentyl side chain lacking ether functionalization. We measured the thermal transitions and transport properties to estimate the performance and trends of this cation class. The samples with imide-type anions form liquids at ambient temperature, and show good transport properties, comparable to imidazolium or ammonium ionic liquids. Despite the dynamics being significantly accelerated, ether functionalization of the cation favors the formation of crystalline solids. Single crystal structure analysis, ab initio calculations and variable temperature nuclear magnetic resonance measurements (VT-NMR) revealed that cation conformations for the ether- and alkyl-chain-substituted are different in both the solid and liquid states. While ether containing cations adopt compact, curled structures, those with pentyl side chains are linear. The Eyring plot revealed that the curled conformation is accompanied by a higher activation energy for rotation around the carbon-nitrogen bonds, due to the coordination of the ether chain as observed by VT-NMR.

Journal article

Neville GM, Dobre A-M, Smith GJ, Micciulla S, Brooks NJ, Arnold T, Welton T, Edler KJet al., 2023, Interactions of Choline and Geranate (CAGE) and Choline Octanoate (CAOT) Deep Eutectic Solvents with Lipid Bilayers, ADVANCED FUNCTIONAL MATERIALS, ISSN: 1616-301X

Journal article

Schroeder D, Philippi F, Schroeder D, Morgenstern B, White AJP, Jochum M, Welton T, Kay CWMet al., 2023, Room temperature ionic liquids with two symmetric ions, CHEMICAL SCIENCE, Vol: 14, Pages: 10340-10346, ISSN: 2041-6520

Journal article

Palumbo O, Paolone A, Philippi F, Rauber D, Welton Tet al., 2023, Dynamics in Quaternary Ionic Liquids with Non-Flexible Anions: Insights from Mechanical Spectroscopy, INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES, Vol: 24, ISSN: 1661-6596

Journal article

Green C, Bilyanska A, Bradley M, Dinsdale J, Hutt L, Backhaus T, Boons F, Bott D, Collins C, Cornell SE, Craig M, Depledge M, Diderich B, Fuller R, Galloway TS, Hutchison GR, Ingrey N, Johnson AC, Kupka R, Matthiessen P, Oliver R, Owen S, Owens S, Pickett J, Robinson S, Sims K, Smith P, Sumpter JP, Tretsiakova-McNally S, Wang M, Welton T, Willis KJ, Lynch Iet al., 2023, A Horizon Scan to Support Chemical Pollution-Related Policymaking for Sustainable and Climate-Resilient Economies, ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY, Vol: 42, Pages: 1212-1228, ISSN: 0730-7268

Journal article

Rauber D, Philippi F, Becker J, Zapp J, Morgenstern B, Kuttich B, Kraus T, Hempelmann R, Hunt P, Welton T, Kay CWMet al., 2023, Anion and ether group influence in protic guanidinium ionic liquids, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 25, Pages: 6436-6453, ISSN: 1463-9076

Journal article

Bejaoui YKJ, Philippi F, Stammler H-G, Radacki K, Zapf L, Schopper N, Goloviznina K, Maibom KAM, Graf R, Sprenger JAP, Bertermann R, Braunschweig H, Welton T, Ignat'ev NV, Finze Met al., 2023, Insights into structure-property relationships in ionic liquids using cyclic perfluoroalkylsulfonylimides, CHEMICAL SCIENCE, Vol: 14, Pages: 2200-2214, ISSN: 2041-6520

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Koutsoukos S, Avila J, Brooks NJJ, Gomes MC, Welton Tet al., 2023, Physical properties and nanostructuring of long-chained homobaric imidazolium ionic liquids, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 25, Pages: 6316-6325, ISSN: 1463-9076

Journal article

Welton T, 2023, Introducing <i>RSC Sustainability</i>, RSC Sustainability, Vol: 1, Pages: 8-9

<jats:p>Editor-in-Chief, Tom Welton, introduces the first issue of <jats:italic>RSC Sustainability</jats:italic>.</jats:p>

Journal article

Palumbo O, Paolone A, Rauber D, Kay CWM, Philippi F, Welton Tet al., 2022, Mechanical spectroscopy study of ionic liquids with quaternary cations: Effect of conformational flexibility, JOURNAL OF ALLOYS AND COMPOUNDS, Vol: 919, ISSN: 0925-8388

Journal article

Beckmann JBB, Rauber D, Philippi F, Goloviznina K, Ward-Williams JA, Sederman AJ, Mantle MD, Padua A, Kay CWM, Welton T, Gladden LFet al., 2022, Molecular Dynamics of Ionic Liquids from Fast-Field Cycling NMR and Molecular Dynamics Simulations, JOURNAL OF PHYSICAL CHEMISTRY B, Vol: 126, Pages: 7143-7158, ISSN: 1520-6106

Journal article

Philippi F, Rauber D, Palumbo O, Goloviznina K, McDaniel J, Pugh D, Suarez S, Fraenza CC, Padua A, Kay CWM, Welton Tet al., 2022, Flexibility is the key to tuning the transport properties of fluorinated imide-based ionic liquids, CHEMICAL SCIENCE, Vol: 13, Pages: 9176-9190, ISSN: 2041-6520

Journal article

Koutsoukos S, Becker J, Dobre A, Fan Z, Othman F, Philippi F, Smith GJ, Welton Tet al., 2022, Synthesis of aprotic ionic liquids, NATURE REVIEWS METHODS PRIMERS, Vol: 2

Journal article

Guan Y, Clark R, Philippi F, Zhang X, Welton Tet al., 2022, How do external forces related to mass and charge affect the structures and dynamics of an ionic liquid?, JOURNAL OF CHEMICAL PHYSICS, Vol: 156, ISSN: 0021-9606

Journal article

Koutsoukos S, Philippi F, Rauber D, Pugh D, Kay C, Welton Tet al., 2022, Effect of the cation structure on the properties of homobaric imidazolium ionic liquids, Physical Chemistry Chemical Physics, Vol: 24, Pages: 6453-6468, ISSN: 1463-9076

In this work we investigate the structure–property relationships in a series of alkylimidazolium ionic liquids with almost identical molecular weight. Using a combination of theoretical calculations and experimental measurements, we have shown that re-arranging the alkyl side chain or adding functional groups results in quite distinct features in the resultant ILs. The synthesised ILs, although structurally very similar, cover a wide spectrum of properties ranging from highly fluid, glass forming liquids to high melting point crystalline salts. Theoretical ab initio calculations provide insight on minimum energy orientations for the cations, which then are compared to experimental X-ray crystallography measurements to extract information on hydrogen bonding and to verify our understanding of the studied structures. Molecular dynamics simulations of the simplest (core) ionic liquids are used in order to help us interpret our experimental results and understand better why methylation of C2 position of the imidazolium ring results in ILs with such different properties compared to their non-methylated analogues.

Journal article

Philippi F, Rauber D, Eliasen KL, Bouscharain N, Niss K, Kay CWM, Welton Tet al., 2022, Pressing matter: why are ionic liquids so viscous?, Chemical Science, Vol: 2022, ISSN: 2041-6520

We use an experimental approach to compare an ionic liquid with a molecular mimic, focusing on viscosities. Charge network and coulombic compaction contribute significantly to the high viscosity of ionic liquids; we discuss the implications on their design and optimisation.

Journal article

Harper JB, Kirchner B, Pavez P, Welton Tet al., 2021, Non-traditional solvent effects in organic reactions, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 23, Pages: 26028-26029, ISSN: 1463-9076

Journal article

Sillero L, Prado R, Welton T, Labidi Jet al., 2021, Extraction of flavonoid compounds from bark using sustainable deep eutectic solvents, SUSTAINABLE CHEMISTRY AND PHARMACY, Vol: 24

Journal article

Rauber D, Philippi F, Kuttich B, Becker J, Kraus T, Hunt P, Welton T, Hempelmann R, Kay CWMet al., 2021, Curled cation structures accelerate the dynamics of ionic liquids, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 23, Pages: 21042-21064, ISSN: 1463-9076

Journal article

Chan KLA, Shalygin AS, Martyanov ON, Welton T, Kazarian SGet al., 2021, High throughput study of ionic liquids in controlled environments with FTIR spectroscopic imaging, JOURNAL OF MOLECULAR LIQUIDS, Vol: 337, ISSN: 0167-7322

Journal article

Sillero L, Prado R, Welton T, Labidi Jet al., 2021, Energy and environmental analysis of flavonoids extraction from bark using alternative solvents, JOURNAL OF CLEANER PRODUCTION, Vol: 308, ISSN: 0959-6526

Journal article

Pontillo ARN, Koutsoukos S, Welton T, Detsi Aet al., 2021, Investigation of the influence of natural deep eutectic solvents (NaDES) in the properties of chitosan-stabilised films, MATERIALS ADVANCES, Vol: 2, Pages: 3954-3964

Journal article

Koutsoukos S, Philippi F, Malaret F, Welton Tet al., 2021, A review on machine learning algorithms for the ionic liquid chemical space, CHEMICAL SCIENCE, Vol: 12, Pages: 6820-6843, ISSN: 2041-6520

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Welton T, 2021, Sustainability and international chemistry collaboration, NATIONAL SCIENCE REVIEW, Vol: 8, ISSN: 2095-5138

Journal article

Toda S, Clark R, Welton T, Shigeto Set al., 2021, Observation of the Pockels Effect in Ionic Liquids and Insights into the Length Scale of Potential-Induced Ordering, LANGMUIR, Vol: 37, Pages: 5193-5201, ISSN: 0743-7463

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Philippi F, Welton T, 2021, Targeted modifications in ionic liquids - from understanding to design†, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 23, Pages: 6993-7021, ISSN: 1463-9076

Journal article

Bakis E, van den Bruinhorst A, Pison L, Palazzo I, Chang T, Kjellberg M, Weber CC, Gomes MC, Welton Tet al., 2021, Mixing divalent ionic liquids: effects of charge and side-chains, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 23, Pages: 4624-4635, ISSN: 1463-9076

Journal article

Lemus J, Santiago R, Hospital-Benito D, Welton T, Hallett JP, Palomar Jet al., 2021, Process Analysis of Ionic Liquid-Based Blends as H<sub>2</sub>S Absorbents: Search for Thermodynamic/Kinetic Synergies, ACS SUSTAINABLE CHEMISTRY & ENGINEERING, Vol: 9, Pages: 2080-2088, ISSN: 2168-0485

Journal article

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