showing 20 related works from this author
Communication: anion-specific response of mesoscopic organization in ionic liquids upon pressurization
2018
One of the outstanding features of ionic liquids is their inherently hierarchical structural organization at mesoscopic spatial scales. Recently experimental and computational studies showed the fading of this feature when pressurising. Here we use simulations to show that this effect is not general: appropriate anion choice leads to an obstinate resistance against pressurization. Published by AIP Publishing.
Solubility and solvation features of native cyclodextrins in 1-ethyl-3-methylimidazolium acetate
2022
The comprehension of the mechanism entailing efficient solvation of cyclodextrins (CD) by green solvents is of great relevance to boost environmentally sustainable usages of smart supramolecular systems. Here, 1-ethyl-3- methylimidazolium acetate, an ecofriendly ionic liquid (IL), is considered as an excellent solvent for native CDs. This IL efficiently dissolves up to 40 wt.% β- and γ-CD already at ambient temperature and X-ray scattering indicates that CDs do not tend to detrimental flocculation under these drastic concentration conditions. Simu- lation techniques reveal the intimate mechanism of CD solvation by the ionic species: while the strong hydrogen bonding acceptor acetate anion i…
Direct experimental observation of mesoscopic fluorous domains in fluorinated room temperature ionic liquids
2017
Fluorinated room temperature ionic liquids (FRTILs) represent a class of solvent media that are attracting great attention due to their IL-specific properties as well as features stemming from their fluorous nature. Medium-to-long fluorous tails constitute a well-defined apolar moiety in the otherwise polar environment. Similarly to the case of alkyl tails, such chains are expected to result in the formation of self-assembled fluorous domains. So far, however, no direct experimental observation has been made of the existence of such structural heterogeneities on the nm scale. We report here the first experimental evidence of the existence of mesoscopic spatial segregation of fluorinated dom…
Mesoscopic structural organization in fluorinated room temperature ionic liquids
2018
The presence of fluorous tails in room-temperature ionic liquids imparts new properties to their already rich spectrum of appealing features. The interest towards this class of compounds that are of ionic nature with melting point less than 25 degrees C is accordingly growing; in particular, compounds bearing relatively long fluorous tails have begun to be considered. In this invited presentation, we show recent results arising from the systematic study of structural properties of a series of fluorinated room temperature ionic liquids, with growing fluorous chain length. At odd with the current understanding of this class of compounds, we show experimentally that they are characterized by t…
Mesoscopic structural organization in fluorinated pyrrolidinium-based room temperature ionic liquids
2019
Abstract In this contribution the microscopic and mesoscopic structural organization in a series of fluorinated room temperature ionic liquids, based on N-methyl-N-alkylpyrrolidinium cations and on bis(perfluoroalkylsulfonyl)imide anions, is investigated, using a synergy of experimental (X-ray and neutron scattering) and computational (Molecular Dynamics) techniques. The proposed ionic liquids are of high interest as electrolyte media for lithium battery applications. Together with information on their good ion transport properties in conjunction with low viscosity, we also describe the existence of nm-scale spatial organization induced by the segregation of fluorous moieties into domains. …
Structure of anisole derivatives by total neutron and X-ray scattering: Evidences of weak C–H⋯O and C–H⋯π interactions in the liquid state
2020
Abstract High resolution, total neutron and X-ray scattering data have been used in synergy with Molecular Dynamics simulations to access atomistic scale insight into the structure of anisole and 2,3,5-trimethylanisole, two aromatic compounds bearing an electron-donating methoxy group. A detailed description is provided for the main interactions occurring in these systems, including π-π stacking and weak hydrogen bonding correlations: C H⋯O and C H⋯π. The existence of preferential orientations of the first shell coordinating molecules and the specific nature of the interactions involving the π cloud and the polar methoxy group have been reported and discussed.
Liquid structure of a water-based, hydrophobic and natural deep eutectic solvent: The case of thymol-water. A Molecular Dynamics study
2022
The structural organization of the first example of a water-based, type V, hydrophobic, natural deep eutectic solvent (DES) is investigated in this work, exploiting the synergy of X-ray scattering and compu- tational techniques. The stoichiometric mixture of thymol:water (4.8:1) has been recently reported to behave as a DES, with a melting point at 6 C, well below the one foreseen for the ideal liquid mixture. Our study provides an atomistic insight into the structural correlations in this system, highlighting the major role played by hydrogen bonding (HB) correlations in affecting morphology as well as the solid– liquid equilibrium. Thymol engages HB-mediated interactions with both thymol …
Mesoscopic organization in ionic liquids.
2017
We discuss some published results and provide new observations concerning the high level of structural complexity that lies behind the nanoscale correlations in ionic liquids (ILs) and their mixtures with molecular liquids. It turns out that this organization is a consequence of the hierarchical construction on both spatial (from ångström to several nanometer) and temporal (from fraction of picosecond to hundreds of nanosecond) scales, which requires joint use of experimental and computational tools. © 2017, Springer International Publishing Switzerland.
Structural features of selected protic ionic liquids based on a super-strong base
2019
Protic ionic liquids (PIL) were prepared from a super-strong base 1,7-diazabicyclo[5.4.0]undec-7-ene (DBU) and super-strong acids, trifluoromethane sulfonic acid (TfOH), and (trifluoromethanesulfonyl)-(nonafluorobutylsulfonyl)imide, (IM14H), ([DBUH][TfO] and [DBUH][IM14], respectively; the latter for the first time) and their chemical and physical properties and structural features have been explored using a synergy of experimental and computational tools. The short range order in neat DBU, as well as the long range structural correlations induced by charge correlation and hydrogen bonding interactions in the ionic liquids, have been explored under ambient conditions, where these compounds …
Structural Features of β-Cyclodextrin Solvation in the Deep Eutectic Solvent, Reline
2020
The inherently amphiphilic nature of native cyclodextrins (CDs) determines their peculiar molecular encapsulation features, enabling applications such as targeted drug nanodelivery, aroma protection, etc. On the contrary, it may also lead to poor solubility in water and other organic solvents and to potentially detrimental flocking in these media, thus posing limitations to more extensive usage. Here we use small angle X-ray scattering to show that deep eutectic solvent reline (1:2 choline chloride:urea) succeeds in dissolving large amounts of beta-CD (at least 800 mg/mL, compared with the solubility in water of 18 mg/mL), without aggregation phenomena occurring. At the microscopic level, m…
Emerging Evidences of Mesoscopic-Scale Complexity in Neat Ionic Liquids and Their Mixtures
2017
Ionic liquids (ILs) represent a blooming class of continuously developing advanced materials, with the aiming of a green chemical industry. Their appealing physical and chemical properties are largely influenced by their micro- and mesoscopic structure that is known to possess a high degree of hierarchical organization. High-impact application fields are largely affected by the complex morphology of neat ionic liquids and their mixtures. This Perspective highlights new arising research directions that point to an enhanced level of structural complexity in several IL-based systems, including mixtures. The latter represent a change in paradigm in the approach to formulate new, task-specific I…
Structure and vibrational features of the protic ionic liquid 1,8-diazabicyclo[5.4.0]-undec-7-ene-8-ium bis(trifluoromethanesulfonyl)amide, [DBUH][TF…
2022
Abstract The Protic Ionic Liquid (PIL) formed by neutralization of the super-strong base 1,7-diazabicyclo[5.4.0]undec-7-ene (DBU) with the super-strong acid bis(trifluoromethanesulfonyl)-imide (TFSI), indicated as [DBUH][TFSI], has been investigated. Its chemical physical properties and structural features have been explored using a synergy of experimental and computational tools. Molecular Dynamics-rationalised X-ray diffraction patterns highlight the major role played by hydrogen bonding (HB) in affecting morphology in this PIL. A comparison between HB features in this and in related PILs has been presented, on the base of far-IR experiments and DFT analysis. Indications of a weaker HB in…
Morphology of 1-alkyl-3-methylimidazolium hexafluorophosphate room temperature ionic liquids
2008
The structural organization in selected room temperature ionic liquids, namely (a) butyl-, (b) hexyl- and (c) octyl-3-methylimidazolium hexafluorophosphate, is investigated by means of X-ray diffraction. We find novel experimental evidences of the existence of a high degree of intermediate range order that is associated to nanoscale segregation of the alkyl chains into the charged matrix. The size of these structural heterogeneities depends linearly from the alkyl chain length. A similar behaviour had been observed in other systems, such as normal alcohols. The slope of such dependence provides hints on the nature of the structural organization of these segregated domains.
Liquid Structure of Trihexyltetradecylphosphonium Chloride at Ambient Temperature: An X-ray Scattering and Simulation Study
2009
We report on an experimental and simulation study done on a representative room temperature ionic liquid, namely tetradecyltrihexylphosphonium chloride, at ambient conditions. The study was conducted using small and wide angle X-ray scattering and molecular dynamics simulations. Both approaches converge in indicating that this material is characterized by the existence of strong P-Cl interactions (with characteristic distances between 3.5 and 5.0 Å) and by the occurrence of nanoscale segregation, despite the symmetric nature of the cation and similarly to other room temperature ionic liquids. A good agreement is found between the structure factor and pair correlation functions obtained from…
Nanoscale organization in the fluorinated room temperature ionic liquid: Tetraethyl ammonium (trifluoromethanesulfonyl)(nonafluorobutylsulfonyl)imide
2018
Fluorinated Room Temperature Ionic Liquids (FRTILs) are a branch of ionic liquids that is the object of growing interest for a wide range of potential applications, due to the synergic combination of specifically ionic features and those properties that stem from fluorous tails. So far limited experimental work exists on the micro-and mesoscopic structural organization in this class of compounds. Such a work is however necessary to fully understand morphological details at atomistic level that would have strong implications in terms of bulk properties. Here we use the synergy between X-ray and neutron scattering together with molecular dynamics simulations to access structural details of a …
Liquid structure of dibutyl sulfoxide
2016
We present experimental (X-ray diffraction) data on the structure of liquid dibutyl sulfoxide at 320 K and rationalise the data by means of molecular dynamics simulations. Not unexpectedly, DBSO bearing a strong dipolar moiety and two medium length, apolar butyl chains, this compound was characterised by a distinct degree of polar vs. apolar structural differentiation at the nm spatial scale, which was fingerprinted by a low Q peak in its X-ray diffraction pattern. Similar to, but to a larger extent than its shorter chain family members (such as DMSO), DBSO was also characterised by an enhanced dipole-dipole correlation, which was responsible for a moderate Kirkwood correlation factor as we…
Oleochemical carbonates: A comprehensive characterization of an emerging class of organic compounds
2022
Dialkyl carbonates (DAC) with short-medium alkyl length - oleochemical carbonates – are attracting attention because of their appealing properties, including low viscosity, flammability, toxicity, environ- mental impact and wide range of applications: lubricants, personal care, fuel additives etc. However, not much is known concerning their chemical physical properties and, more importantly, on the nature of microscopic correlations that eventually determine bulk performances. In view of this paucity, we pre- sent a large exploration of a series of chemical physical properties of a set of DACs ranging from dimethyl up to didodecyl carbonate. This study extends previously determined database…
Liquid structure of a choline chloride-water natural deep eutectic solvent: A molecular dynamics characterization
2021
The liquid structure of a representative of the first water-in-salt (WiS) Natural Deep Eutectic Solvents (NADES), hereinafter indicated as aquoline, a mixture of choline chloride (ChCl) and water with molar ratio 1:3.33, is ex- plored at ambient conditions. Using Molecular Dynamics (MD) simulation tools, we extract structural informa- tion at atomistic level on the nature of inter-correlations between the different moieties. Despite being a very fluid liquid, with much lower viscosity than other common ChCl-based DES, aquoline turns out to be very struc- tured. Computed X-ray and neutron weighted scattering patterns (the latter also on selectively deuterated mix- tures) highlight the existe…
Microscopic structural and dynamic features in triphilic room temperature ionic liquids
2019
Here we report a thorough investigation of the microscopic and mesoscopic structural organization in a series of triphilic fluorinated room temperature ionic liquids, namely [1-alkyl, 3-methylimidazolium][(trifluoromethanesulfonyl)(nonafluorobutylsulfonyl)imide], with alkyl=ethyl, butyl, octyl ([C(n)mim][IM14], n = 2, 4, 8), based on the synergic exploitation of X-ray and Neutron Scattering and Molecular Dynamics simulations. This study reveals the strong complementarity between X-ray/neutron scattering in detecting the complex segregated morphology in these systems at mesoscopic spatial scales. The use of MD simulations delivering a very good agreement with experimental data allows us to g…
Liquid Structure Scenario of the Archetypal Supramolecular Deep Eutectic Solvent: Heptakis(2,6-di-O-methyl)-β-cyclodextrin/levulinic Acid
2023
The concept of supramolecular solvents has been recently introduced, and the extended liquid-state window accessible for mixtures of functionalized cyclodextrins (CDs) with hydrogen bond (HB) donor species, e.g., levulinic acid, led to the debut of supramolecular deep eutectic solvents (SUPRA-DES). These solvents retain CD’s inclusion ability and complement it with enhanced solvation effectiveness due to an extended HB network. However, so far, these promising features were not rationalized in terms of a microscopic description, thus hindering a more complete capitalization. This is the first joint experimental and computational study on the archetypal SUPRA-DES: heptakis- (2,6-di-O-methyl)…