Communication: Nanoscale structure of tetradecyltrihexylphosphonium based ionic liquids

Hettige, Jeevapani J.; Araque, Juan C.; Kashyap, Hemant K.; Margulis, Claudio J.

doi:10.1063/1.4944678

Cited by 46 publications

(50 citation statements)

References 143 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“… 116 − 126 Since this is a pattern of alternation, same type species (polar–polar and apolar–apolar) show peaks in partial subcomponents of S ( q ) at the prepeak region, whereas opposite type species (polar–apolar) show an antipeak; notice that positive and negative species are considered “same type species” in this q regime because they are both polar. 123 , 124 This is clearly depicted in Figure 8 , where polar cationic and anionic heads form networks that are separated by other networks via tails that act as spacers.…”

Section: Resultsmentioning

confidence: 98%

A Brief Guide to the Structure of High-Temperature Molten Salts and Key Aspects Making Them Different from Their Low-Temperature Relatives, the Ionic Liquids

2021

Self Cite

View full text Add to dashboard Cite

High-temperature molten salt research is undergoing somewhat of a renaissance these days due to the apparent advantage of these systems in areas related to clean and sustainable energy harvesting and transfer. In many ways, this is a mature field with decades if not already a century of outstanding work devoted to it. Yet, much of this work was done with pioneering experimental and computational setups that lack the current day capabilities of synchrotrons and high-performance-computing systems resulting in deeply entrenched results in the literature that when carefully inspected may require revision. Yet, in other cases, access to isotopically substituted ions make those pioneering studies very unique and prohibitively expensive to carry out nowadays. There are many review articles on molten salts, some of them cited in this perspective, that are simply outstanding and we dare not try to outdo those. Instead, having worked for almost a couple of decades already on their low-temperature relatives, the ionic liquids, this is the perspective article that some of the authors would have wanted to read when embarking on their research journey on high-temperature molten salts. We hope that this will serve as a simple guide to those expanding from research on ionic liquids to molten salts and vice versa , particularly, when looking into their bulk structural features. The article does not aim at being comprehensive but instead focuses on selected topics such as short- and intermediate-range order, the constraints on force field requirements, and other details that make the high- and low-temperature ionic melts in some ways similar but in others diametrically opposite.

show abstract

Section: Resultsmentioning

confidence: 98%

A Brief Guide to the Structure of High-Temperature Molten Salts and Key Aspects Making Them Different from Their Low-Temperature Relatives, the Ionic Liquids

2021

Self Cite

View full text Add to dashboard Cite

show abstract

“…Their studies described the morphology of the segregated domains as a sponge-like structure rather than a lamellar organization. Furthermore, Hettige et al 29 studied the structural behavior of the same cation ([P66614 + ]) coupled with six different anions, and found that the structure of the ILs is defined by charge and polar alternation. They observed that a temperature increase in the IL system results in a better defined polar network.…”

Section: Introductionmentioning

confidence: 99%

Diffusional Dynamics of Tetraalkylphosphonium Ionic Liquid Films Measured by Fluorescence Correlation Spectroscopy

et al. 2019

View full text Add to dashboard Cite

Fluorescence correlation spectroscopy (FCS) is applied to investigate the diffusional dynamics of hydrophilic (Atto 590) and amphiphilic (DiD) fluorophores in a series of alkylphosphonium ionic liquid (IL) films ([P4448][Cl], [P6668][Cl], [P66614][Cl], and [P66614][NTf2]) in order to determine diffusional parameters and to elucidate nanoscale structural heterogeneities within the IL. From the measured correlation functions, the diffusion coefficients of the fluorescent molecules are estimated, rendering values that span from 0.39-1.2 and 0.146-5.2 µm 2 /s, for Atto 590 and DiD, respectively. A decrease in the diffusion coefficients is measured as the alkyl chain increases, coincident with a decrease in their viscosity. Interestingly, deviations from the Brownian diffusion behavior of the fluorescent probes in the ILs are observed, showing a time-dependent diffusion coefficient in most of the cases. These deviations can be attributed to the presence of nanoscale structural heterogeneities in the tetraalkylphosphonium ILs. These results confirm experimentally the presence of nanosegregation in tetraalkylphosphonium ILs, which has previously been observed in molecular dynamics (MD) studies.

show abstract

“…The heterogeneous microstructures and liquid morphologies are even more distinct in tetraalkylphosphonium based ILs as there are four aliphatic chains in tetraalkylphosphonium cations and each one can be tuned with varied aliphatic substituents [48][49][50][51], and mutated with different polar and apolar groups [14,15]. Additionally, tetraalkylphosphonium cations can be associated with various anions and molecular liquids [27,[50][51][52][53][54][55][56][57], leading to striking ionic structures and distinct liquid morphologies in IL matrices. Gontrani et al studied a trihexyltetradecylphosphonium chloride ([P 6,6,6,14 ]Cl) IL combining X-ray scattering technique and computer simulation, and alluded the existence of polar segregation at nanoscopic level in IL matrix [58].…”

Section: Introductionmentioning

confidence: 99%

Microstructures and dynamics of tetraalkylphosphonium chloride ionic liquids

Wang

Sarman

et al. 2017

The Journal of Chemical Physics

View full text Add to dashboard Cite

Atomistic simulations have been performed to investigate the effect of aliphatic chain length in tetraalkylphosphonium cations on liquid morphologies, microscopic ionic structures, and dynamical quantities of tetraalkylphosphonium chloride ionic liquids. The liquid morphologies are characterized by sponge-like interpenetrating polar and apolar networks in ionic liquids consisting of tetraalkylphosphonium cations with short aliphatic chains. The lengthening aliphatic chains in tetraalkylphosphonium cations lead to polar domains consisting of chloride anions and central polar groups in cations being partially or totally segregated in ionic liquid matrices due to a progressive expansion of apolar domains in between. Prominent polarity alternation peaks and adjacency correlation peaks are observed at low and high q range in total X-ray scattering structural functions, respectively, and their peak positions gradually shift to lower q values with lengthening aliphatic chains in tetraalkylphosphonium cations. The charge alternation peaks registered in the intermediate q range exhibit complicated tendencies due to a cancellation of peaks and anti-peaks in partial structural functions for ionic subcomponents. The particular microstructures and liquid morphologies in tetraalkylphosphonium chloride ionic liquids intrinsically contribute to distinct dynamics characterized by mean square displacements, van Hove correlation functions, and non-Gaussian parameters for ionic species in the heterogeneous ionic environment. Most tetraalkylphosphonium cations have higher translational mobilities than their partner anions due to strong coordination of chloride anions with central polar groups in tetraalkylphosphonium cations through strong Coulombic and hydrogen bonding interactions. The increase of aliphatic chain length in tetraalkylphosphonium cations leads to a concomitant shift of van Hove correlation functions and non-Gaussian parameters to larger radial distances and longer time scales, respectively, indicating the enhanced translational dynamical heterogeneities of tetraalkylphosphonium cations and the corresponding chloride anions.

show abstract

Communication: Nanoscale structure of tetradecyltrihexylphosphonium based ionic liquids

Cited by 46 publications

References 143 publications

A Brief Guide to the Structure of High-Temperature Molten Salts and Key Aspects Making Them Different from Their Low-Temperature Relatives, the Ionic Liquids

A Brief Guide to the Structure of High-Temperature Molten Salts and Key Aspects Making Them Different from Their Low-Temperature Relatives, the Ionic Liquids

Diffusional Dynamics of Tetraalkylphosphonium Ionic Liquid Films Measured by Fluorescence Correlation Spectroscopy

Microstructures and dynamics of tetraalkylphosphonium chloride ionic liquids

Contact Info

Product

Resources

About