The unseen evidence of Reduced Ionicity: The elephant in (the) room temperature ionic liquids

Mariani, Alessandro; Bonomo, Matteo; Gao, Xinpei; Centrella, Barbara; Nucara, A.; Buscaino, Roberto; Barbero, Nadia; Gontrani, Lorenzo; Passerini, Stefano

doi:10.1016/j.molliq.2020.115069

Cited by 36 publications

(69 citation statements)

References 116 publications

(205 reference statements)

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“…Observed molar conductivities are then calculated by normalizing reported specific conductivity measurements by the overall concentration of the ionic liquid via the density and molecular weight of the ionic liquid, as is done in prior works. 43,44,52,53 To validate database findings, we perform alternating current (AC) conductivity measurements and particle tracking microrheology to measure viscosity in a class of common ionic liquids, 1-alkyl-3methylimidazolium bis(trifluoromethylsulfonyl)imide (CnMIm TFSI, n = 2,4,10,12). Microrheology enables viscosity to be measured precisely in small samples, making it an ideal approach using small amounts of fluid in an isolated environment.…”

Section: Methodsmentioning

confidence: 99%

Bridging Database Analysis with Microrheology to Reveal Super-Hydrodynamic Conductivity Scaling Regimes in Ionic Liquids

Cashen

Donoghue

Schmeiser

et al. 2022

Preprint

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Ion transport through electrolytes critically impacts the performance of batteries and other electrochemical devices. Many frameworks used to predict and tune ion transport, such as the Nernst-Einstein model, assume hydrodynamic transport mechanisms, and hence focus on maximizing electrolyte conductivity by minimizing bulk viscosity. However, the emergence of solid-state electrolytes illustrates that selective, non-hydrodynamic ion transport provides promising avenues for enhancing ionic transport in electrolytes. Increasingly, selective ion transport mechanisms, such as hopping, are proposed for concentrated electrolytes, including ionic liquid-derived materials. Yet viscosity-conductivity scaling relationships in ionic liquids are still often analyzed with hydrodynamic models. Here, we report a data-centric analysis of how well hydrodynamic transport models describe the scaling between viscosity and conductivity in neat ionic liquids by merging three databases to bridge physical properties and chemical descriptors. With this expansive data set, we constrained our scaling analysis using ion sizes defined using simulated molecular volumes, as opposed to prior approaches that estimate sizes from activity coefficients or rely on ad-hoc estimates. Remarkably, we find that many commonly studied ionic liquids exhibit positive deviations from the Nernst-Einstein model, implying that ions move faster than hydrodynamic limitations should allow. We experimentally verify these positive deviations in a common class of ionic liquids using microrheology and conductivity measurements. Our results highlight overlooked super-hydrodynamic regimes in ionic liquid viscosity-conductivity scaling and point to opportunities to understand mechanisms of correlated ion motion in ionic liquids. We further show data science and machine learning tools can improve predictions of conductivity from molecular properties, including demonstrating predictions can be made using only computational features. Our findings reveal that many ionic liquids exhibit super-hydrodynamic viscosity-conductivity scaling, which could be harnessed to influence the behavior of electrochemical devices.

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Section: Methodsmentioning

confidence: 99%

Bridging Database Analysis with Microrheology to Reveal Super-Hydrodynamic Conductivity Scaling Regimes in Ionic Liquids

Cashen

Donoghue

Schmeiser

et al. 2022

Preprint

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“…If placed in a Walden plot EG/KF 6:1 and more clearly EtOH/KF 6:1 show a negative displacement from the bisector (not shown), probably due to the lowest amount of hydroxyl moieties that are not able to completely disrupt the ion pairs formed. [45] In the light of these outcomes, we selected DES Gly/KF 6:1 as a model system and we added 4nitrobenzenediazonium tetrafluoroborate (1a) to it. Surprisingly, almost instantaneous decomposition (in about 5 minutes; brisk boiling due to nitrogen loss) of 1a occurred and nitrobenzene (2a) was formed as the only product (Table 2; entry 6).…”

Section: Clarification Of Proposed Mixtures Chemical Naturementioning

confidence: 99%

How do arenediazonium salts behave in deep eutectic solvents? A combined experimental and computational approach

Antenucci

Bonomo

Ghigo

et al. 2021

Journal of Molecular Liquids

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“…The complexity of the [N 4444 ][Xan] spectrum lead to the determination of its melting point using another melting point apparatus. Since [N 4444 ][Ur] starts decomposing before melting, this compound is not categorized as an IL, according to the recent definition by Mariani et al [3]. The melting temperature of [N 4444 ][Theob] and [N 4444 ][Theop] are very similar.…”

Section: Synthesis and Characterization Of Purine-based Ilsmentioning

confidence: 99%

“…In fact, the first definition of ILs was proposed by Walden et al [2] as salts with melting temperatures below an arbitrary threshold of 373 K, in order to differentiate these from typical salts. More recently, the definition of ILs was refined by Mariani et al [3], who proposed that ILs are water-free organic salts with a melting temperature lower than decomposition temperature.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Purine-Based Ionic Liquids and Their Applications

et al. 2021

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Bio-based ionic liquids (ILs) are being increasingly sought after, as they are more sustainable and eco-friendly. Purines are the most widely distributed, naturally occurring N-heterocycles, but their low water-solubility limits their application. In this work, four purines (theobromine, theophylline, xanthine, and uric acid) were combined with the cation tetrabutylammonium to synthesize bio-based ILs. The physico–chemical properties of the purine-based ILs were characterized, including their melting and decomposition temperatures and water-solubility. The ecotoxicity against the microalgae Raphidocelis subcapitata was also determined. The ILs show good thermal stability (>457 K) and an aqueous solubility enhancement ranging from 53- to 870-fold, in comparison to their respective purine percursors, unlocking new prospects for their application where aqueous solutions are demanded. The ecotoxicity of these ILs seems to be dominated by the cation, and it is similar to chloride-based IL, emphasizing that the use of natural anions does not necessarily translate to more benign ILs. The application of the novel ILs in the formation of aqueous biphasic systems (ABS), and as solubility enhancers, was also evaluated. The ILs were able to form ABS with sodium sulfate and tripotassium citrate salts. The development of thermoresponsive ABS, using sodium sulfate as a salting-out agent, was accomplished, with the ILs having different thermosensitivities. In addition, the purine-based ILs acted as solubility enhancers of ferulic acid in aqueous solution.

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The unseen evidence of Reduced Ionicity: The elephant in (the) room temperature ionic liquids

Cited by 36 publications

References 116 publications

Bridging Database Analysis with Microrheology to Reveal Super-Hydrodynamic Conductivity Scaling Regimes in Ionic Liquids

Bridging Database Analysis with Microrheology to Reveal Super-Hydrodynamic Conductivity Scaling Regimes in Ionic Liquids

How do arenediazonium salts behave in deep eutectic solvents? A combined experimental and computational approach

Synthesis of Purine-Based Ionic Liquids and Their Applications

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