{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,14]],"date-time":"2026-04-14T04:17:50Z","timestamp":1776140270968,"version":"3.50.1"},"reference-count":25,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2021,1,12]],"date-time":"2021-01-12T00:00:00Z","timestamp":1610409600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJMS"],"abstract":"<jats:p>Understanding the behavior of a chemical compound at a molecular level is fundamental, not only to explain its macroscopic properties, but also to enable the control and optimization of these properties. The present work aims to characterize a set of systems based on the ionic liquids [Aliquat][Cl] and [Aliquat][FeCl4] and on mixtures of these with different concentrations of DMSO by means of 1H NMR relaxometry, diffusometry and X-ray diffractometry. Without DMSO, the compounds reveal locally ordered domains, which are large enough to induce order fluctuation as a significant relaxation pathway, and present paramagnetic relaxation enhancement for the [Aliquat][Cl] and [Aliquat][FeCl4] mixture. The addition of DMSO provides a way of tuning both the local order of these systems and the relaxation enhancement produced by the tetrachloroferrate anion. Very small DMSO volume concentrations (at least up to 1%) lead to enhanced paramagnetic relaxation without compromising the locally ordered domains. Larger DMSO concentrations gradually destroy these domains and reduce the effect of paramagnetic relaxation, while solvating the ions present in the mixtures. The paramagnetic relaxation was explained as a correlated combination of inner and outer-sphere mechanisms, in line with the size and structure differences between cation and anion. This study presents a robust method of characterizing paramagnetic ionic systems and obtaining a consistent analysis for a large set of samples having different co-solvent concentrations.<\/jats:p>","DOI":"10.3390\/ijms22020706","type":"journal-article","created":{"date-parts":[[2021,1,12]],"date-time":"2021-01-12T20:11:31Z","timestamp":1610482291000},"page":"706","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":7,"title":["Tuning the 1H NMR Paramagnetic Relaxation Enhancement and Local Order of [Aliquat]+-Based Systems Mixed with DMSO"],"prefix":"10.3390","volume":"22","author":[{"given":"Rui","family":"Cordeiro","sequence":"first","affiliation":[{"name":"Center of Physics and Engineering of Advanced Materials, Departamento de F\u00edsica, Instituto Superior T\u00e9cnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisbon, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4320-9683","authenticated-orcid":false,"given":"Maria J.","family":"Beira","sequence":"additional","affiliation":[{"name":"Center of Physics and Engineering of Advanced Materials, Departamento de F\u00edsica, Instituto Superior T\u00e9cnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisbon, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1415-0929","authenticated-orcid":false,"given":"Carlos","family":"Cruz","sequence":"additional","affiliation":[{"name":"Center of Physics and Engineering of Advanced Materials, Departamento de F\u00edsica, Instituto Superior T\u00e9cnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisbon, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9254-1864","authenticated-orcid":false,"given":"Jo\u00e3o L.","family":"Figueirinhas","sequence":"additional","affiliation":[{"name":"Center of Physics and Engineering of Advanced Materials, Departamento de F\u00edsica, Instituto Superior T\u00e9cnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisbon, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0890-6133","authenticated-orcid":false,"given":"Marta C.","family":"Corvo","sequence":"additional","affiliation":[{"name":"CENIMAT-Faculdade de Ci\u00eancias e Tecnologia, Universidade Nova de Lisboa, Campus da Caparica, 2829-516 Caparica, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7356-8455","authenticated-orcid":false,"given":"Pedro L.","family":"Almeida","sequence":"additional","affiliation":[{"name":"CENIMAT-Faculdade de Ci\u00eancias e Tecnologia, Universidade Nova de Lisboa, Campus da Caparica, 2829-516 Caparica, Portugal"},{"name":"Physics Department, ISEL, R. Conselheiro Em\u00eddio Navarro, 1, 1959-007 Lisboa, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2691-3110","authenticated-orcid":false,"given":"Andreia A.","family":"Rosatella","sequence":"additional","affiliation":[{"name":"Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7284-5948","authenticated-orcid":false,"given":"Carlos A. M.","family":"Afonso","sequence":"additional","affiliation":[{"name":"Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003 Lisboa, Portugal"}]},{"given":"Carla I.","family":"Daniel","sequence":"additional","affiliation":[{"name":"LAQV\/Requimte, Departamento de Qu\u00edmica, Faculdade de Ci\u00eancias e Tecnologia, Universidade Nova de Lisboa, Campus de Caparica, 2829-516 Caparica, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6450-3019","authenticated-orcid":false,"given":"Pedro J.","family":"Sebasti\u00e3o","sequence":"additional","affiliation":[{"name":"Center of Physics and Engineering of Advanced Materials, Departamento de F\u00edsica, Instituto Superior T\u00e9cnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisbon, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2021,1,12]]},"reference":[{"key":"ref_1","first-page":"405","article-title":"Molecular weights and electrical conductivity of several fused salts","volume":"1800","author":"Walden","year":"1914","journal-title":"Bull. Russian Acad. Sci."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"792","DOI":"10.1126\/science.1090313","article-title":"Ionic Liquids\u2013Solvents of the Future?","volume":"302","author":"Rogers","year":"2003","journal-title":"Science"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"361","DOI":"10.1016\/j.cattod.2009.07.070","article-title":"Reusable and efficient polymer-supported task-specific ionic liquid catalyst for cycloaddition of epoxide with CO2","volume":"148","author":"Sun","year":"2009","journal-title":"Catal. Today"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"5921","DOI":"10.1021\/ma050093a","article-title":"Ionic Liquid Catalyst for Biphasic Atom Transfer Radical Polymerization of Methyl Methacrylate","volume":"38","author":"Ding","year":"2005","journal-title":"Macromolecules"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"6","DOI":"10.1016\/j.chroma.2007.11.109","article-title":"Ionic liquids in separation techniques","volume":"1184","author":"Berthod","year":"2008","journal-title":"J. Chromatogr. A"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"400","DOI":"10.1021\/ja077233b","article-title":"High Gas Storage Capacities for Ionic Liquids through Chemical Complexation","volume":"130","author":"Tempel","year":"2008","journal-title":"J. Am. Chem. Soc."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"658","DOI":"10.1016\/j.jpowsour.2006.02.077","article-title":"Pure ionic liquid electrolytes compatible with a graphitized carbon negative electrode in rechargeable lithium-ion batteries","volume":"162","author":"Ishikawa","year":"2006","journal-title":"J. Power Sources"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"11472","DOI":"10.1021\/acs.jpcb.7b07929","article-title":"1H NMR Relaxometry and Diffusometry Study of Magnetic and Nonmagnetic Ionic Liquid-Based Solutions: Cosolvent and Temperature Effects","volume":"121","author":"Beira","year":"2017","journal-title":"J. Phys. Chem. B"},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Del Sesto, R.E., McCleskey, T.M., Burrell, A.K., Baker, G.A., Thompson, J.D., Scott, B.L., Wilkes, J.S., and Williams, P. (2008). Structure and magnetic behavior of transition metal based ionic liquids. Chem. Comm., 447\u2013449.","DOI":"10.1039\/B711189D"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"16","DOI":"10.1016\/j.jcis.2014.04.023","article-title":"Hydraulic pressures generated in Magnetic Ionic Liquids by paramagnetic fluid\/air interfaces inside of uniform tangential magnetic fields","volume":"428","author":"Scovazzo","year":"2014","journal-title":"J. Colloid Interface Sci."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"36","DOI":"10.1016\/j.ssnmr.2010.07.001","article-title":"Desktop fast-field cycling nuclear magnetic resonance relaxometer","volume":"38","author":"Sousa","year":"2010","journal-title":"Solid State NMR"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"679","DOI":"10.1103\/PhysRev.73.679","article-title":"Relaxation effect in nuclear magnetic resonance absorption","volume":"73","author":"Bloembergen","year":"1948","journal-title":"Phys. Rev."},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Abragam, A. (1961). The Principles of Nuclear Magnetism, Clarendon Press.","DOI":"10.1119\/1.1937646"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"962","DOI":"10.1103\/PhysRev.92.962","article-title":"Nuclear Spin Relaxation by Translational Diffusion","volume":"92","author":"Torrey","year":"1953","journal-title":"Phys. Rev."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"400","DOI":"10.1103\/PhysRev.182.400","article-title":"Nuclear Spin Relaxation by Translational Diffusion in Liquid Ethane","volume":"182","author":"Harmon","year":"1969","journal-title":"Phys. Rev."},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Dong, R. (1997). Nuclear Magnetic Resonance of Liquid Crystals, Springer.","DOI":"10.1007\/978-1-4612-1954-5"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"8600","DOI":"10.1103\/PhysRevB.49.8600","article-title":"Nmr-study of the T(1) Relaxation Dispersion In the Smectic Mesophase of 4-chlorophenyl 4-undecyloxybenzoate","volume":"49","author":"Anoardo","year":"1994","journal-title":"Phys. Rev. B"},{"key":"ref_18","first-page":"263","article-title":"Interactions and Fluctuations Deduced from Proton Field-cycling Relaxation Spectroscopy of Polypeptides, Dna, Muscles, and Algae","volume":"68","author":"Kimmich","year":"1986","journal-title":"J. Magn. Reson."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1105","DOI":"10.1515\/zna-1992-1102","article-title":"Nitrogen Nuclear-Quadrupole Resonance Dips in the Proton Spin Relaxation Dispersion of Nematic and Smectic Thermotropic Liquid-Crystals","volume":"47","author":"Pusiol","year":"1992","journal-title":"Z. Fur. Naturforschung Sect. A-A J. Phys. Sci."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"572","DOI":"10.1063\/1.1743771","article-title":"Proton Relaxation Times in Paramagnetic Solutions","volume":"27","author":"Bloembergen","year":"1957","journal-title":"J. Chem. Phys."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"842","DOI":"10.1063\/1.1731684","article-title":"Proton Relaxation Times in Paramagnetic Solutions. Effects of Electron Spin Relaxation","volume":"34","author":"Bloembergen","year":"1961","journal-title":"J. Chem. Phys."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"261","DOI":"10.1063\/1.1742867","article-title":"Nuclear Magnetic Interactions in the HF Molecule","volume":"25","author":"Solomon","year":"1956","journal-title":"J. Chem. Phys."},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Merbach, A., Helm, L., and Toth, E. (2013). The Chemistry of Contrast Agents in Medical Magnetic Resonance Imaging, Wiley. [2nd ed.].","DOI":"10.1002\/9781118503652"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"015017","DOI":"10.1088\/0143-0807\/35\/1\/015017","article-title":"The art of model fitting to experimental results","volume":"35","year":"2014","journal-title":"Eur. J. Phys."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"54","DOI":"10.1016\/j.molliq.2012.02.019","article-title":"Measurements and correlations of viscosity, conductivity and density of an hydrophobic ionic liquid (Aliquat 336) mixtures with a non-associated dipolar aprotic solvent (DMC)","volume":"169","author":"Litaiem","year":"2012","journal-title":"J. Mol. Liq."}],"container-title":["International Journal of Molecular Sciences"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1422-0067\/22\/2\/706\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T05:10:19Z","timestamp":1760159419000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1422-0067\/22\/2\/706"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,1,12]]},"references-count":25,"journal-issue":{"issue":"2","published-online":{"date-parts":[[2021,1]]}},"alternative-id":["ijms22020706"],"URL":"https:\/\/doi.org\/10.3390\/ijms22020706","relation":{},"ISSN":["1422-0067"],"issn-type":[{"value":"1422-0067","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,1,12]]}}}