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1. Additive polarizabilities in ionic liquids

Author

Bernardes, Carlos ES, Shimizu, Karina, Lopes, José Nuno Canongia, Marquetand, Philipp, Heid, Esther, Steinhauser, Othmar, and Schröder, Christian

Subjects
Physics - Chemical Physics, Condensed Matter - Soft Condensed Matter
Abstract

An extended Designed regression analysis of experimental data on density and refractive indices of several classes of ionic liquids yielded statistically averaged atomic volumes and polarizabilities of the constituting atoms. These values can be used to predict the molecular volume and polarizability of an unknown ionic liquid as well as its mass density and refractive index. Our approach does not need information on the molecular structure of the ionic liquid, but it turned out that the discrimination of the hybridization state of the carbons improved the overall result. Our results are not only compared to experimental data but also to quantum-chemical calculations. Furthermore, fractional charges of ionic liquid ions and their relation to polarizability are discussed.

Published
2021
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10. Understanding the Liquid Structure in Mixtures of Ionic Liquids with Semiperfluoroalkyl or Alkyl Chains

Author

Elstone, Naomi S., primary, Shimizu, Karina, additional, Shaw, Emily V., additional, Lane, Paul D., additional, D’Andrea, Lucía, additional, Demé, Bruno, additional, Mahmoudi, Najet, additional, Rogers, Sarah E., additional, Youngs, Sarah, additional, Costen, Matthew L., additional, McKendrick, Kenneth G., additional, Canongia Lopes, Jose N., additional, Bruce, Duncan W., additional, and Slattery, John M., additional

Published
2023
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16. Exploring Mannosylpurines as Copper Chelators and Cholinesterase Inhibitors with Potential for Alzheimer’s Disease

Author

Schino, Ignazio, primary, Cantore, Mariangela, additional, de Candia, Modesto, additional, Altomare, Cosimo D., additional, Maria, Catarina, additional, Barros, João, additional, Cachatra, Vasco, additional, Calado, Patrícia, additional, Shimizu, Karina, additional, Freitas, Adilson A., additional, Oliveira, Maria C., additional, Ferreira, Maria J., additional, Lopes, José N. C., additional, Colabufo, Nicola A., additional, and Rauter, Amélia P., additional

Published
2022
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17. Synthesis of New Purine Nucleosides as potential Metal Chelators and Anticholinesterase Agents

Author

Maria, Catarina, primary, Barros, João, additional, Xavier, Nuno, additional, Shimizu, Karina, additional, Freitas, Adilson, additional, Ferreira, Mª João, additional, Schino, Ignazio, additional, Cantore, Mariangela, additional, de Candia, Modesto, additional, Colabufo, Nicola, additional, Lopes, José Nuno Canongia, additional, and Rauter, Amélia, additional

Published
2022
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18. Exploring Mannosylpurines as Copper Chelators and Cholinesterase Inhibitors with Potential for Alzheimer's Disease.

Author

Schino, Ignazio, Cantore, Mariangela, de Candia, Modesto, Altomare, Cosimo D., Maria, Catarina, Barros, João, Cachatra, Vasco, Calado, Patrícia, Shimizu, Karina, Freitas, Adilson A., Oliveira, Maria C., Ferreira, Maria J., Lopes, José N. C., Colabufo, Nicola A., and Rauter, Amélia P.

Subjects
ALZHEIMER'S disease, CHOLINESTERASE inhibitors, COPPER, MOLECULAR conformation, CYCLOOXYGENASE inhibitors, SECRETASE inhibitors, CHELATING agents, COPPER catalysts, IRON
Abstract

Alzheimer's Disease (AD) is characterized by a progressive cholinergic neurotransmission imbalance, with a decrease of acetylcholinesterase (AChE) activity followed by a significant increase of butyrylcholinesterase (BChE) in the later AD stages. BChE activity is also crucial for the development of Aβ plaques, the main hallmarks of this pathology. Moreover, systemic copper dyshomeostasis alters neurotransmission leading to AD. In the search for structures targeting both events, a set of novel 6-benzamide purine nucleosides was synthesized, differing in glycone configuration and N7/N9 linkage to the purine. Their AChE/BChE inhibitory activity and metal ion chelating properties were evaluated. Selectivity for human BChE inhibition required N9-linked 6-deoxy-α-d-mannosylpurine structure, while all three tested β-d-derivatives appeared as non-selective inhibitors. The N9-linked l-nucleosides were cholinesterase inhibitors except the one embodying either the acetylated sugar or the N-benzyl-protected nucleobase. These findings highlight that sugar-enriched molecular entities can tune bioactivity and selectivity against cholinesterases. In addition, selective copper chelating properties over zinc, aluminum, and iron were found for the benzyl and acetyl-protected 6-deoxy-α-l-mannosyl N9-linked purine nucleosides. Computational studies highlight molecular conformations and the chelating molecular site. The first dual target compounds were disclosed with the perspective of generating drug candidates by improving water solubility. [ABSTRACT FROM AUTHOR]

Published
2023
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23. Structure and dynamics of mica-confined films of [C10C1Pyrr][NTf2] ionic liquid.

Author

Freitas, Adilson Alves de, Shimizu, Karina, Smith, Alexander M., Perkin, Susan, and Canongia Lopes, José Nuno

Subjects
*IONIC liquids, *MOLECULAR dynamics, *MICA, *NANOPARTICLE synthesis, *X-ray diffraction measurement, *X-ray scattering, *POLAR solvent analysis
Abstract

The structure of the ionic liquid 1-decyl-1-methylpyrrolidinium bis[(trifluoromethane)sulfonyl]imide, [C10C1Pyrr][NTf2], has been probed using Molecular Dynamics (MD) simulations. The simulations endeavour to model the behaviour of the ionic liquid in bulk isotropic conditions and also at interfaces and in confinement. The MD results have been confronted and validated with scattering and surface force experiments reported in the literature. The calculated structure factors, distribution functions, and density profiles were able to provide molecular and mechanistic insights into the properties of these long chain ionic liquids under different conditions, in particular those that lead to the formation of multi-layered ionic liquid films in confinement. Other properties inaccessible to experiment such as in-plane structures and relaxation rates within the films have also been analysed. Overall the work contributes structural and dynamic information relevant to many applications of ionic liquids with long alkyl chains, ranging from nanoparticle synthesis to lubrication. [ABSTRACT FROM AUTHOR]

Published
2018
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26. Charge-transfer complexation as a general phenomenon in the copigmentation of anthocyanins

Author

Silva, Palmira Ferreira da, Lima, Joao C., Freitas, Adilson A., Shimizu, Karina, Macanita, Antonio L., and Quina, Frank H.

Subjects
Anthocyanin -- Electric properties, Ionization -- Research, Charge transfer -- Research, Chemicals, plastics and rubber industries
Abstract

Theoretical and experimental evidence is provided for the generality of charge transfer from the copigment to the flavylium cation, as a major driving force for the stabilization of anthocyanin-copigment complexes. Correlations provide a straightforward means of estimating the relative copigmentation strengths of potential copigment molecules based on calculated values of their ionization potentials.

Published
2005

31. Enhanced dissolution of ibuprofen using ionic liquids as catanionic hydrotrope

Author

Sintra, Tania E, Shimizu, Karina, Ventura, Sonia P M, Shimizu, Seishi, Canongia Lopes, Jose Nuno, and Coutinho, Joao A P

Abstract

The therapeutic effectiveness of a drug largely depends on its bioavailability, and thus ultimately on its aqueous solubility. Hydrotropes are compounds able to enhance the solubility of hydrophobic substances in aqueous media and therefore are extensively used in the formulation of drugs and personal care products. Recently, some ionic liquids were shown to display a strong ability to enhance the solubility of biomolecules through hydrotropy. In this work, the impact of the ionic liquid chemical structures and their concentration on the solubility of ibuprofen were evaluated and compared with the performance of conventional hydrotropes. The results obtained clearly evidence the exceptional capacity of ionic liquids to enhance the solubility of ibuprofen. [C4C1im][SCN] and [C4C1im][N(CN)2] seem to be the most promising ionic liquids for ibuprofen solubilisation, where an increase in the solubility of 60- and 120-fold was observed with ionic liquids concentrations of circa 1 mol∙kg-1, respectively. Dynamic light scattering and molecular dynamics simulations were used to investigate the mechanism of the IL-mediated drug solubility and the results obtained indicate that the structure of aqueous solutions of ionic liquids and the role it plays on the formation of ionic liquids-drug aggregates is the mechanism driving the hydrotropic dissolution.

Published
2018

32. Exploring the bulk-phase structure of ionic liquid mixtures using small-angle neutron scattering

Author

Cabry, Christopher Patrick, D'Andrea, Lucia, Shimizu, Karina, Grillo, Isabelle, Li, Peixun, Rogers, Sarah, Bruce, Duncan Watson, Canongia Lopes, Jose Nuno, and Slattery, John Martin

Abstract

Small-angle neutron scattering experiments, supported by molecular dynamics simulations, have been performed on a range of compositions of the [C2mim]1-x[C12mim]x[Tf2N] ionic liquid mixture system. Isotopic contrast variation, through selective deuteration of both cations, has been used to assist in fitting the data to different scattering models. These data, and subsequent fitting, show that the structure of the ionic liquid mixtures changes substantially as a function of composition. Mixtures where x < 0.32 are dominated by aggregates of amphiphilic [C12mim]+ ions in the relatively polar [C2mim][Tf2N] solvent. Compositions where x > 0.32 can be described as bicontinuous, containing networks of both polar and non-polar domains, where the C12 chains of the [C12mim]+ ions percolate through the system to form a continuous non-polar sub-phase. Temperature-dependent scattering experiments suggest that there is relatively little change in bulk structure in these liquids between 20 and 60 oC. The presence of water, however, does influence some aspects of the liquid structure in a composition that is rich in [C2mim][Tf2N] (where x = 0.24).

Published
2018

36. Nanosegregation and Structuring in the Bulk and at the Surface of Ionic-Liquid Mixtures

Author

Slattery, John Martin, Bruce, Duncan Watson, Cabry, Christopher Patrick, Canongia Lopes, Jose Nuno, Costen, Matthew L., D'Andrea, Lucia, Grillo, Isabelle, Marshall, Brooks C., McKendrick, Kenneth G., Minton, Timothy K., Purcell, Simon M., Rogers, Sarah, Shimizu, Karina, Smoll, Eric J., and Tesa-Serrate, Maria A.

Abstract

Ionic-liquid (IL) mixtures hold great promise, as they allow liquids with a wide range of properties to be formed by mixing two common components, rather than by synthesizing a large array of pure ILs with different chemical structures. In addition, these mixtures can exhibit a range of properties and structural organization that depend on their composition, which opens up new possibilities for the composition-dependent control of IL properties for particular applications. However, the fundamental properties, structure and dynamics of IL mixtures are currently poorly understood, which limits their more widespread application. This paper presents the first comprehensive investigation into the bulk and surface properties of IL mixtures formed from two commonly encountered ILs: 1-ethyl-3-methylimidazolium and 1-dodecyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C2mim][Tf2N] and [C12mim][Tf2N]). Physical property measurements (viscosity, conductivity and density) find that these IL mixtures are not well described by simple mixing laws, suggesting that their structure and dynamics are strongly composition-dependent. Small-angle X-ray and neutron scattering (SAXS and SANS) measurements, alongside molecular dynamics (MD) simulations, show that at low mole fractions of [C12mim][Tf2N], the bulk of the IL is composed of small aggregates of [C12mim]+ ions in a [C2mim][Tf2N] matrix, which is driven by nano-segregation of the long alkyl chains and the polar parts of the IL. As the proportion of [C12mim][Tf2N] in the mixtures increases, the size and number of aggregates increases until the C12 alkyl chains percolate through the system and a bicontinuous network of polar and non-polar domains is formed. Reactive atom scattering-laser-induced fluorescence (RAS-LIF) experiments, also supported by MD simulations, have been used to probe the surface structure of these mixtures. It is found that the vacuum-IL interface is enriched significantly in C12 alkyl chains, even in mixtures low in the long-chain component. These data show, contrary to previous suggestions, that the [C12mim]+ ion is surface active in this binary IL mixture. However, the surface does not become saturated in C12 chains as its proportion in the mixtures increases and remains unsaturated in pure [C12mim][Tf2N].

Published
2017

37. Liquid-Crystalline Ionic Liquids as Ordered Reaction Media for the Diels–Alder Reaction

Author

Slattery, John Martin, Bruce, Duncan Watson, Gao, Yanan, Shimizu, Karina, and Canongia Lopes, Jose Nuno

Abstract

Liquid-crystalline ionic liquids (LCILs) are ordered materials that have untapped potential to be used as reaction media for synthetic chemistry. This paper investigates the potential for the ordered structures of LCILs to influence the stereochemical outcome of the Diels–Alder reaction between cyclopentadiene and methyl acrylate. The ratio of endo- to exo-product from this reaction was monitored for a range of ionic liquids (ILs) and LCILs. Comparison of the endo:exo ratios in these reactions as a function of cation, anion and liquid crystallinity of the reaction media, allowed for the effects of liquid crystallinity to be distinguished from anion effects or cation alkyl chain length effects. These data strongly suggest that the proportion of exo-product increases as the reaction media is changed from an isotropic IL to a LCIL. A detailed molecular dynamics (MD) study suggests that this effect is related to different hydrogen bonding interactions between the reaction media and the exo- and endo-transition states in solvents with layered, smectic ordering compared to those that are isotropic.

Published
2016

38. Mutual Solubility of Water and Structural/Positional Isomers of N-Alkylpyridinium-Based Ionic Liquids

Author

Freire, Mara G., Neves, Catarina M. S. S., Shimizu, Karina, Bernardes, Carlos E. S., Marrucho, Isabel M., Coutinho, João A. P., Lopes, José N. Canongia, and Rebelo, Luís Paulo N.

Abstract

Despite many previous important contributions to the characterization of the liquid−liquid phase behavior of ionic liquids (ILs) plus water systems, a gap still exists as far as the effect of isomers (of ILs) is concerned. Therefore, in this work, a comprehensive study of the liquid−liquid equilibria between water and isomeric pyridinium-based ionic liquids has been performed. Atmospheric pressure mutual solubilities between water and pyridinium-based ionic liquids combined with the common anion bis[(trifluoromethyl)sulfonyl]imide were experimentally determined between (288.15 and 318.15) K. The main goal of this work is to study the isomeric effects on the pyridinium-based cation, namely, the structural and positional isomerism, as well as the alkyl side chain length. To the best of our knowledge, the influence of both structural and positional isomerism on the liquid−liquid behavior in ionic-liquid-water-containing systems is an unexplored field and is here assessed for the first time. Moreover, from the experimental solubility data, several infinite dilution molar thermodynamic functions of solution, namely, the Gibbs energy, the enthalpy, and the entropy, were estimated and discussed. In addition, aiming at gathering a broader picture of the underlying thermodynamic solvation phenomenon, molecular dynamics simulations were also carried out for the same experimental systems.

Published
2024
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39. Molecular Force Field for Ionic Liquids V: Hydroxyethylimidazolium, Dimethoxy-2- Methylimidazolium, and Fluoroalkylimidazolium Cations and Bis(Fluorosulfonyl)Amide, Perfluoroalkanesulfonylamide, and Fluoroalkylfluorophosphate Anions

Author

Shimizu, Karina, Almantariotis, Dimitrios, Gomes, Margarida F. Costa, Pádua, Agílio. A. H., and Canongia Lopes, José N.

Abstract

In this article, the fifth of a series that describes the parametrization of a force field for the molecular simulation of ionic liquids within the framework of statistical mechanics, we have modeled cations belonging to the hydroxyethylimidazolium, dimethoxy-2-methylimidazolium, and fluoroalkylimidazolium families and anions of the bis(fluorosulfonyl)amide, perfluoroalkanesulfonylamide, and fluoroalkylfluorophosphate families. The development of the force field, created in the spirit of the OPLS-AA model in a stepwise manner and oriented toward the calculation of equilibrium thermodynamic and structural properties in the liquid and crystalline phases, is discussed in detail. Because of the transferability of the present force field, the ions studied here can be combined with those reported in our four previous publications to create a large variety of ionic liquids that can be studied by molecular simulation. The present extension of the force field was validated by comparison of simulation results with experimental crystal structure and liquid density data.

Published
2024
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40. Unraveling the Morphology of [CnC1Im]Cl Ionic Liquids Combining Cluster and Aggregation Analyses

Author

Frömbgen, Tom, Canongia Lopes, José Nuno, Kirchner, Barbara, and Shimizu, Karina

Abstract

A characteristic feature of ionic liquids is their nanosegregation, resulting in the formation of polar and nonpolar domains. The influence of increasing the alkyl side chain on the morphology of ionic liquids has been the subject of many studies. Typically, the polar network (charged part of the cation and anion) constitutes a continuous subphase that partially breaks to allow the formation of a nonpolar domain with the increase of the alkyl chain. As the nonpolar network expands, the number of tails per aggregate increases until the ionic liquid percolates. In this work, we demonstrate how the complementary software packages TRAVIS and AGGREGATES can be employed in conjunction to gain insights into the size and morphology of the [CnC1Im]Cl family, with n∈ {2, 4, 6, 8, 10, 12}. The combination of the two approaches rounds off the picture of the intricate arrangement and structural features of the alkyl chains.

Published
2024
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47. Structure and dynamics of ionic liquids: general discussion

Author

Addicoat, Matthew, primary, Atkin, Rob, additional, Canongia Lopes, José Nuno, additional, Costa Gomes, Margarida, additional, Firestone, Millicent, additional, Gardas, Ramesh, additional, Halstead, Simon, additional, Hardacre, Christopher, additional, Hardwick, Laurence J., additional, Holbrey, John, additional, Hunt, Patricia, additional, Ivaništšev, Vladislav, additional, Jacquemin, Johan, additional, Jones, Robert, additional, Kirchner, Barbara, additional, Lynden-Bell, Ruth, additional, MacFarlane, Doug, additional, Marlair, Guy, additional, Medhi, Himani, additional, Mezger, Markus, additional, Pádua, Agílio, additional, Pantenburg, Isabel, additional, Perkin, Susan, additional, Reid, Joshua E. S. J., additional, Rutland, Mark, additional, Saha, Satyen, additional, Shimizu, Karina, additional, Slattery, John M., additional, Swadźba-Kwaśny, Malgorzata, additional, Tiwari, Shraeddha, additional, Tsuzuki, Seiji, additional, Uralcan, Betul, additional, van den Bruinhorst, Adriaan, additional, Watanabe, Masayoshi, additional, and Wishart, James, additional

Published
2018
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50. Nanostructure of trialkylmethylammonium bistriflamide ionic liquids studied by molecular dynamics

Author

Shimizu, Karina, Padua, Aglio A. H., and Lopes, Jose N. Canongia

Subjects
Molecular dynamics -- Usage, Ionic liquids -- Structure, Ionic liquids -- Analysis, Ammonium chloride -- Structure, Ammonium chloride -- Spectra, Ammonium compounds -- Structure, Ammonium compounds -- Spectra, Ammonium paratungstate -- Structure, Ammonium paratungstate -- Spectra, Chemicals, plastics and rubber industries
Published
2010

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