Publications
244 results found
Bejaoui YKJ, Philippi F, Stammler H-G, et al., 2023, Insights into structure-property relationships in ionic liquids using cyclic perfluoroalkylsulfonylimides., Chem Sci, Vol: 14, Pages: 2200-2214, ISSN: 2041-6520
Room temperature ionic liquids of cyclic sulfonimide anions ncPFSI (ring size: n = 4-6) with the cations [EMIm]+ (1-ethyl-3-methylimidazolium), [BMIm]+ (1-butyl-3-methylimidazolium) and [BMPL]+ (BMPL = 1-butyl-1-methylpyrrolidinium) have been synthesized. Their solid-state structures have been elucidated by single-crystal X-ray diffraction and their physicochemical properties (thermal behaviour and stability, dynamic viscosity and specific conductivity) have been assessed. In addition, the ion diffusion was studied by pulsed field gradient stimulated echo (PFGSTE) NMR spectroscopy. The decisive influence of the ring size of the cyclic sulfonimide anions on the physicochemical properties of the ILs has been revealed. All ILs show different properties compared to those of the non-cyclic TFSI anion. While these differences are especially distinct for ILs with the very rigid 6cPFSI anion, the 5-membered ring anion 5cPFSI was found to result in ILs with relatively similar properties. The difference between the properties of the TFSI anion and the cyclic sulfonimide anions has been rationalized by the rigidity (conformational lock) of the cyclic sulfonimide anions. The comparison of selected IL properties was augmented by MD simulations. These highlight the importance of π+-π+ interactions between pairs of [EMIm]+ cations in the liquid phase. The π+-π+ interactions are evident for the solid state from the molecular structures of the [EMIm]+-ILs with the three cyclic imide anions determined by single-crystal X-ray diffraction.
Koutsoukos S, Avila J, Brooks NJJ, et 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
Rauber D, Philippi F, Becker J, et al., 2023, Anion and ether group influence in protic guanidinium ionic liquids, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 25, Pages: 6436-6453, ISSN: 1463-9076
Palumbo O, Paolone A, Rauber D, et 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
Beckmann JBB, Rauber D, Philippi F, et 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
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- Citations: 1
Philippi F, Rauber D, Palumbo O, et 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
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- Citations: 4
Koutsoukos S, Becker J, Dobre A, et al., 2022, Synthesis of aprotic ionic liquids, NATURE REVIEWS METHODS PRIMERS, Vol: 2
Guan Y, Clark R, Philippi F, et 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
Koutsoukos S, Philippi F, Rauber D, et 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.
Philippi F, Rauber D, Eliasen KL, et 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.
Harper JB, Kirchner B, Pavez P, et al., 2021, Non-traditional solvent effects in organic reactions, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 23, Pages: 26028-26029, ISSN: 1463-9076
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- Citations: 1
Sillero L, Prado R, Welton T, et al., 2021, Extraction of flavonoid compounds from bark using sustainable deep eutectic solvents, SUSTAINABLE CHEMISTRY AND PHARMACY, Vol: 24
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- Citations: 4
Rauber D, Philippi F, Kuttich B, et al., 2021, Curled cation structures accelerate the dynamics of ionic liquids, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 23, Pages: 21042-21064, ISSN: 1463-9076
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- Citations: 8
Chan KLA, Shalygin AS, Martyanov ON, et al., 2021, High throughput study of ionic liquids in controlled environments with FTIR spectroscopic imaging, JOURNAL OF MOLECULAR LIQUIDS, Vol: 337, ISSN: 0167-7322
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- Citations: 3
Welton T, 2021, Sustainability and international chemistry collaboration, NATIONAL SCIENCE REVIEW, Vol: 8, ISSN: 2095-5138
Pontillo ARN, Koutsoukos S, Welton T, et 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
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- Citations: 3
Sillero L, Prado R, Welton T, et al., 2021, Energy and environmental analysis of flavonoids extraction from bark using alternative solvents, JOURNAL OF CLEANER PRODUCTION, Vol: 308, ISSN: 0959-6526
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- Citations: 7
Koutsoukos S, Philippi F, Malaret F, et 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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- Citations: 41
Toda S, Clark R, Welton T, et 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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- Citations: 4
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
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- Citations: 45
Bakis E, van den Bruinhorst A, Pison L, et al., 2021, Mixing divalent ionic liquids: effects of charge and side-chains, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 23, Pages: 4624-4635, ISSN: 1463-9076
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- Citations: 3
Lemus J, Santiago R, Hospital-Benito D, et al., 2021, Process Analysis of Ionic Liquid-Based Blends as H2S Absorbents: Search for Thermodynamic/Kinetic Synergies, ACS SUSTAINABLE CHEMISTRY & ENGINEERING, Vol: 9, Pages: 2080-2088, ISSN: 2168-0485
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- Citations: 5
Welton T, 2020, A big difference in diversity, Education in Chemistry, Vol: 57, ISSN: 0013-1350
Philippi F, Rauber D, Kuttich B, et al., 2020, Ether functionalisation, ion conformation and the optimisation of macroscopic properties in ionic liquids, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 22, Pages: 23038-23056, ISSN: 1463-9076
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- Citations: 25
Philippi F, Pugh D, Rauber D, et al., 2020, Conformational design concepts for anions in ionic liquids, Chemical Science, Vol: 11, Pages: 6405-6422, ISSN: 2041-6520
The identification of specific design concepts for the in silico design of ionic liquids (ILs) has been accomplished using theoretical methods. Molecular building blocks, such as interchangeable functional groups, are used to design a priori new ILs which have subsequently been experimentally investigated. The conformational design concepts are developed by separately and systematically changing the central (imide), bridging (sulfonyl) and end (trifluoromethyl) group of the bis(trifluoromethanesulfonyl)imide [N(Tf)2]− anion and examining the resultant potential energy surfaces. It is shown that these design concepts can be used to tune separately the minimum energy geometry, transition state barrier height and relative stability of different conformers. The insights obtained have been used to design two novel anions for ILs, trifluoroacetyl(methylsulfonyl)imide [N(Ms)(TFA)]− and acetyl(trifluoromethanesulfonyl)imide [N(Tf)(Ac)]−. The computationally predicted structures show excellent agreement with experimental structures obtained from X-ray crystallography. [C4C1im][N(Tf)(Ac)] and [C4C1im][N(Ms)(TFA)] ILs have been synthesised and ion diffusion coefficients examined using pulsed field gradient stimulated echo NMR spectroscopy. Significantly increased diffusion was observed for the more flexible [N(Tf)(Ac)]− compared with the more rigid [N(Ms)(TFA)]− analogue. Furthermore, a pronounced impact on the fluidity was observed. The viscosity of the IL with the rigid anion was found to be twice as high as the viscosity of the IL with the flexible anion. The design concepts presented in this work will enable researchers in academia and industry to tailor anions to provide ILs with specific desired properties.
Clark R, Nawawi MA, Dobre A, et al., 2020, The effect of structural heterogeneity upon the microviscosity of ionic liquids, Chemical Science, Vol: 11, Pages: 6121-6133, ISSN: 2041-6520
The behaviour of two molecular rotors, one charged – 3,3′-diethylthiacarbocyanine iodide (Cy3) and one neutral – 8-[4-decyloxyphenyl]-4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY-C10), have been studied in various ionic liquids. The fluorescent decay lifetime has been used to elucidate the structure of the immediate region around the rotor. The neutral BODIPY-C10 was found to prefer the non-polar alkyl chain environment, leading to two trends in the lifetime of the dye: one when it was fully partitioned into the non-polar domain, and one when it also sampled polar moieties. The positively charged Cy3 dye showed a complex relationship between the bulk viscosity of the ionic liquid and lifetime of the molecular rotor. This was attributed to a combination of polarity related spectral changes, changes in anion cages around the dye, and temperature dependent fluorescent lifetimes alongside the dependence of the rotor upon the viscosity.
Mann SK, Devgan MK, Franks WT, et al., 2020, MAS NMR Investigation of Molecular Order in an Ionic Liquid Crystal, JOURNAL OF PHYSICAL CHEMISTRY B, Vol: 124, Pages: 4975-4988, ISSN: 1520-6106
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- Citations: 10
Sillero L, Prado R, Welton T, et al., 2020, Energetic and environmental analysis of different techniques for biomolecules extractions, Chemical Engineering Transactions, Vol: 81, Pages: 631-636
There is an increase in the demand of natural and environmentally more sustainable products, for that the biorefinery is a very promising tool due to its capacity to develop more sustainable products. Biorefinery processes are being optimized to reduce the global energy consumption and environmental impact by increasing extraction yields. In this work, two intensification techniques, microwave-assisted extraction and ultrasound-assisted extraction, have been tested and their results have been compared with those obtained by the conventional method. The best results were obtained with microwave-assisted extraction. Another studied aspect was the selectivity of the solvent, for which three ionic liquids ([C4C1im][Br], [C4C1im][OAc] and [C4C1im][BF4]) and two deep eutectic solvents (Choline Chloride:Urea (1:2) and Choline Chloride: 1,4-butanediol (1:2)) were tested. The best extraction yield was obtained with Choline Chloride:Urea (1:2). The objective of this work was the evaluation of the impact of the processes in terms of energy consumption and solvents' toxicity, in addition to the determination of the extraction process performance. For this, an analysis of energy consumption was performed, with microwave assisted extraction having the lowest consumption. For the toxicity study different parameters were taken into account, concluding that deep eutectic solvents are a good option. In conclusion, the combination of microwave assisted extraction with deep eutectic solvents can be considered the most efficient extraction method.
Clark R, von Domaros M, McIntosh AJS, et al., 2019, Effect of an external electric field on the dynamics and intramolecular structures of ions in an ionic liquid, JOURNAL OF CHEMICAL PHYSICS, Vol: 151, ISSN: 0021-9606
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- Citations: 17
Weber CC, Brooks NJ, Castiglione F, et al., 2019, On the structural origin of free volume in 1-alkyl-3-methylimidazolium ionic liquid mixtures: a SAXS and 129Xe NMR study., Physical Chemistry Chemical Physics, Vol: 21, Pages: 5999-6010, ISSN: 1463-9076
Ionic liquid (IL) mixtures enable the design of fluids with finely tuned structural and physicochemical properties for myriad applications. In order to rationally develop and design IL mixtures with the desired properties, a thorough understanding of the structural origins of their physicochemical properties and the thermodynamics of mixing needs to be developed. To elucidate the structural origins of the excess molar volume within IL mixtures containing ions with different alkyl chain lengths, 3 IL mixtures containing 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ILs have been explored in a joint small angle X-ray scattering (SAXS) and 129Xe NMR study. The apolar domains of the IL mixtures were shown to possess similar dimensions to the largest alkyl chain of the mixture with the size evolution determined by whether the shorter alkyl chain was able to interact with the apolar domain. 129Xe NMR results illustrated that the origin of excess molar volume in these mixtures was due to fluctuations within these apolar domains arising from alkyl chain mismatch, with the formation of a greater number of smaller voids within the IL structure. These results indicate that free volume effects for these types of mixtures can be predicted from simple considerations of IL structure and that the structural basis for the formation of excess molar volume in these mixtures is substantially different to IL mixtures formed of different types of ions.
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