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Structural Evolution of the Butylated Hydroxytoluene/Menthol Hydrophobic Eutectic Solvent upon Methanol and Ethanol Cosolvent Addition. J Mol Liq 2023. [DOI: 10.1016/j.molliq.2023.121302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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D'Angelo P, Migliorati V, Gibiino A, Busato M. Direct Observation of Contact Ion-Pair Formation in La 3+ Methanol Solution. Inorg Chem 2022; 61:17313-17321. [PMID: 36255362 PMCID: PMC9627567 DOI: 10.1021/acs.inorgchem.2c02932] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
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An approach combining molecular dynamics (MD) simulations
and X-ray
absorption spectroscopy (XAS) has been used to carry out a comparative
study about the solvation properties of dilute La(NO3)3 solutions in water and methanol, with the aim of elucidating
the still elusive coordination of the La3+ ion in the latter
medium. The comparison between these two systems enlightened a different
behavior of the nitrate counterions in the two environments: while
in water the La(NO3)3 salt is fully dissociated
and the La3+ ion is coordinated by water molecules only,
the nitrate anions are able to enter the metal first solvation shell
to form inner-sphere complexes in methanol solution. The speciation
of the formed complexes showed that the 10-fold coordination is preferential
in methanol solution, where the nitrate anions coordinate the La3+ cations in a monodentate fashion and the methanol molecules
complete the solvation shell to form an overall bicapped square antiprism
geometry. This is at variance with the aqueous solution where a more
balanced situation is observed between the 9- and 10-fold coordination.
An experimental confirmation of the MD results was obtained by La
K-edge XAS measurements carried out on 0.1 M La(NO3)3 solutions in the two solvents, showing the distinct presence
of the nitrate counterions in the La3+ ion first solvation
sphere of the methanol solution. The analysis of the extended X-ray
absorption fine structure (EXAFS) part of the absorption spectrum
collected on the methanol solution was carried out starting from the
MD results and confirmed the structural arrangement observed by the
simulations. The formation of contact ion pairs between
the La3+ ions and the nitrate anions has been demonstrated
in diluted methanol
solution using a combined approach using Molecular Dynamics simulations
and X-ray absorption spectroscpy.
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Affiliation(s)
- Paola D'Angelo
- Department of Chemistry, University of Rome "La Sapienza", P.le Aldo Moro 5, 00185 Rome, Italy
| | - Valentina Migliorati
- Department of Chemistry, University of Rome "La Sapienza", P.le Aldo Moro 5, 00185 Rome, Italy
| | - Alice Gibiino
- Department of Chemistry, University of Rome "La Sapienza", P.le Aldo Moro 5, 00185 Rome, Italy
| | - Matteo Busato
- Department of Chemistry, University of Rome "La Sapienza", P.le Aldo Moro 5, 00185 Rome, Italy
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Migliorati V, Busato M, D’Angelo P. Solvation structure of the Hg(NO3)2 and Hg(TfO)2 salts in dilute aqueous and methanol solutions: An insight into the Hg2+ coordination chemistry. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.119801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Busato M, Fazio G, Tavani F, Pollastri S, D'Angelo P. Solubilization and coordination of the HgCl 2 molecule in water, methanol, acetone, and acetonitrile: an X-ray absorption investigation. Phys Chem Chem Phys 2022; 24:18094-18102. [PMID: 35880669 DOI: 10.1039/d2cp02106d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
X-ray absorption spectroscopy (XAS) has been employed to carry out structural characterization of the local environment around mercury after the dissolution of the HgCl2 molecule. A combined EXAFS (extended X-ray absorption fine structure) and XANES (X-ray absorption near edge structure) data analysis has been performed on the Hg L3-edge absorption spectra recorded on 0.1 M HgCl2 solutions in water, methanol (MeOH), acetone and acetonitrile. The Hg-Cl distance determined by EXAFS (2.29(2)-2.31(2) Å) is always comparable to that found in the HgCl2 crystal (2.31(2) Å), demonstrating that the HgCl2 molecule dissolves in these solvents without dissociating. A small sensitivity of EXAFS to the solvent molecules interacting with HgCl2 has been detected and indicates a high degree of configurational disorder associated with this contribution. XANES data analysis, which is less affected by the disorder, was therefore carried out for the first time on these systems to shed light into the still elusive structural arrangement of the solvent molecules around HgCl2. The obtained results show that, in aqueous and MeOH solutions, the XANES data are compatible with three solvent molecules arranged around the HgCl2 unit to form a trigonal bipyramidal structure. The determination of the three-body Cl-Hg-Cl distribution shows a certain degree of uncertainty around the average 180° bond angle value, suggesting that the HgCl2 molecule probably vibrates in the solution around a linear configuration.
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Affiliation(s)
- Matteo Busato
- Department of Chemistry, University of Rome "La Sapienza", P.le A. Moro 5, 00185, Rome, Italy.
| | - Giuseppe Fazio
- Department of Chemistry, University of Rome "La Sapienza", P.le A. Moro 5, 00185, Rome, Italy.
| | - Francesco Tavani
- Department of Chemistry, University of Rome "La Sapienza", P.le A. Moro 5, 00185, Rome, Italy.
| | - Simone Pollastri
- Elettra-Sincrotrone Trieste S.C.p.A, s.s. 14, km 163.5, I-34149, Basovizza, Trieste, Italy
| | - Paola D'Angelo
- Department of Chemistry, University of Rome "La Sapienza", P.le A. Moro 5, 00185, Rome, Italy.
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Busato M, Tofoni A, Mannucci G, Tavani F, Del Giudice A, Colella A, Giustini M, D'Angelo P. On the Role of Water in the Formation of a Deep Eutectic Solvent Based on NiCl 2·6H 2O and Urea. Inorg Chem 2022; 61:8843-8853. [PMID: 35616906 PMCID: PMC9199011 DOI: 10.1021/acs.inorgchem.2c00864] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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The metal-based deep
eutectic solvent (MDES) formed by NiCl2·6H2O and urea in 1:3.5 molar ratio has been
prepared for the first time and characterized from a structural point
of view. Particular accent has been put on the role of water in the
MDES formation, since the eutectic could not be obtained with the
anhydrous form of the metal salt. To this end, mixtures at different
water/MDES molar ratios (W) have been studied with
a combined approach exploiting molecular dynamics and ab initio simulations, UV–vis and near-infra-red spectroscopies, small-
and wide-angle X-ray scattering, and X-ray absorption spectroscopy
measurements. In the pure MDES, a close packing of Ni2+ ion clusters forming oligomeric agglomerates is present thanks to
the mediation of bridging chloride anions and water molecules. Conversely,
urea poorly coordinates the metal ion and is mostly found in the interstitial
regions among the Ni2+ ion oligomers. This nanostructure
is disrupted upon the introduction of additional water, which enlarges
the Ni–Ni distances and dilutes the system up to an aqueous
solution of the MDES constituents. In the NiCl2·6H2O 1:3.5 MDES, the Ni2+ ion is coordinated on average
by one chloride anion and five water molecules, while water easily
saturates the metal solvation sphere to provide a hexa-aquo coordination
for increasing W values. This multidisciplinary study
allowed us to reconstruct the structural arrangement of the MDES and
its aqueous mixtures on both short- and intermediate-scale levels,
clarifying the fundamental role of water in the eutectic formation
and challenging the definition at the base of these complex systems. The metal-based deep eutectic solvent
formed by NiCl2·6H2O and urea in 1:3.5
a molar ratio was
prepared for the first time, and its aqueous mixtures were characterized
from a structural point of view, highlighting the fundamental role
of water in the eutectic formation.
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Affiliation(s)
- Matteo Busato
- Department of Chemistry, University of Rome "La Sapienza", P.le A. Moro 5, Rome 00185, Italy
| | - Alessandro Tofoni
- Department of Chemistry, University of Rome "La Sapienza", P.le A. Moro 5, Rome 00185, Italy
| | - Giorgia Mannucci
- Department of Chemistry, University of Rome "La Sapienza", P.le A. Moro 5, Rome 00185, Italy
| | - Francesco Tavani
- Department of Chemistry, University of Rome "La Sapienza", P.le A. Moro 5, Rome 00185, Italy
| | - Alessandra Del Giudice
- Department of Chemistry, University of Rome "La Sapienza", P.le A. Moro 5, Rome 00185, Italy
| | - Andrea Colella
- Department of Chemistry, University of Rome "La Sapienza", P.le A. Moro 5, Rome 00185, Italy
| | - Mauro Giustini
- Department of Chemistry, University of Rome "La Sapienza", P.le A. Moro 5, Rome 00185, Italy
| | - Paola D'Angelo
- Department of Chemistry, University of Rome "La Sapienza", P.le A. Moro 5, Rome 00185, Italy
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Busato M, Del Giudice A, Di Lisio V, Tomai P, Migliorati V, Gentili A, Martinelli A, D’Angelo P. Fate of a Deep Eutectic Solvent upon Cosolvent Addition: Choline Chloride-Sesamol 1:3 Mixtures with Methanol. ACS SUSTAINABLE CHEMISTRY & ENGINEERING 2021; 9:12252-12261. [PMID: 34552826 PMCID: PMC8442355 DOI: 10.1021/acssuschemeng.1c03809] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 08/07/2021] [Indexed: 06/13/2023]
Abstract
The changes upon methanol (MeOH) addition in the structural arrangement of the highly eco-friendly deep eutectic solvent (DES) formed by choline chloride (ChCl) and sesamol in 1:3 molar ratio have been studied by means of attenuated total reflection Fourier transform infrared spectroscopy, small- and wide-angle X-ray scattering (SWAXS), and molecular dynamics simulations. The introduction of MeOH into the DES promotes the increase of the number of Cl-MeOH hydrogen bonds (HBs) through the replacement of sesamol and choline molecules from the chloride anion coordination sphere. This effect does not promote the sesamol-sesamol, choline-choline, and sesamol-choline interactions, which remain as negligible as in the pure DES. Differently, the displaced sesamol and choline molecules are solvated by MeOH, which also forms HBs with other MeOH molecules, so that the system arranges itself to keep the overall amount of HBs maximized. SWAXS measurements show that this mechanism is predominant up to MeOH/DES molar ratios of 20-24, while after this ratio value, the scattering profile is progressively diluted in the cosolvent background and decreases toward the signal of pure MeOH. The ability of MeOH to interplay with all of the DES components produces mixtures with neither segregation of the components at nanoscale lengths nor macroscopic phase separation even for high MeOH contents. These findings have important implications for application purposes since the understanding of the pseudophase aggregates formed by a DES with a dispersing cosolvent can help in addressing an efficient extraction procedure.
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Affiliation(s)
- Matteo Busato
- Department of Chemistry, University of Rome ”La Sapienza”, P.le A. Moro 5, 00185 Rome, Italy
| | - Alessandra Del Giudice
- Department of Chemistry, University of Rome ”La Sapienza”, P.le A. Moro 5, 00185 Rome, Italy
| | - Valerio Di Lisio
- Department of Chemistry, University of Rome ”La Sapienza”, P.le A. Moro 5, 00185 Rome, Italy
| | - Pierpaolo Tomai
- Department of Chemistry, University of Rome ”La Sapienza”, P.le A. Moro 5, 00185 Rome, Italy
| | - Valentina Migliorati
- Department of Chemistry, University of Rome ”La Sapienza”, P.le A. Moro 5, 00185 Rome, Italy
| | - Alessandra Gentili
- Department of Chemistry, University of Rome ”La Sapienza”, P.le A. Moro 5, 00185 Rome, Italy
| | - Andrea Martinelli
- Department of Chemistry, University of Rome ”La Sapienza”, P.le A. Moro 5, 00185 Rome, Italy
| | - Paola D’Angelo
- Department of Chemistry, University of Rome ”La Sapienza”, P.le A. Moro 5, 00185 Rome, Italy
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