Trace water changes metal ion speciation in deep eutectic solvents: Ce3+ solvation and nanoscale water clustering in choline chloride-urea-water mixtures

Oliver Hammond; Elly Kim Bathke; Daniel T. Bowron; Karen J. Edler

doi:10.1021/acs.inorgchem.3c02205

Trace water changes metal ion speciation in deep eutectic solvents: Ce³⁺ solvation and nanoscale water clustering in choline chloride-urea-water mixtures

Oliver Hammond
, Elly Kim Bathke
, Daniel T. Bowron
, Karen J. Edler

Department of Chemistry

Rutherford Appleton Laboratory

Research output: Contribution to journal › Article › peer-review

12 Citations (SciVal)

Abstract

Eutectic mixtures of choline chloride, urea, and water in deep eutectic solvent (DES)/water molar hydration ratios (w) of 2, 5, and 10, with dissolved cerium salt, were measured using neutron diffraction with isotopic substitution. Structures were modeled using empirical potential structure refinement (EPSR). Ce3+ was found to form highly charged complexes with a mean coordination number between 7 and 8, with the shell containing mostly chloride, followed by water. The shell composition is strongly affected by the molar ratio of dilution, as opposed to the mass or volume fraction, due to the high affinity of Cl– and H2O ligands that displace less favorable interactions with ligands such as urea and choline. The presence of Ce3+ salt disrupted the bulk DES structure slightly, making it more electrolyte-like. The measured coordination shell of choline showed significant discrepancies from the statistical noninteracting distribution, highlighting the nonideality of the blend. Cluster analysis revealed the trace presence of percolating water clusters (25 ≥ n ≥ 2) in solvent compositions of 5 and 10w for the first time.

Original language	English
Pages (from-to)	18069–18078
Number of pages	10
Journal	Inorganic Chemistry
Volume	62
Issue number	44
Early online date	20 Oct 2023
DOIs	https://doi.org/10.1021/acs.inorgchem.3c02205
Publication status	Published - 6 Nov 2023

Bibliographical note

Funders: Engineering and Physical Sciences Research Council - EP/L016354/1; ISIS Neutron and Muon Source - 3578

Funding Information:
The authors thank ISIS Neutron & Muon Source for access to NIMROD under experiment number RB1610312; this can also be used to freely access raw neutron data via the ISIS-ICAT system. OSH thanks STFC (ISIS studentship agreement 3578) and the EPSRC Centre for Doctoral Training in Sustainable Chemical Technologies (EP/L016354/1) for PhD funding. The authors acknowledge Ronak Kakadiya for assisting in UV–vis spectroscopy measurements.

Funding

The authors thank ISIS Neutron & Muon Source for access to NIMROD under experiment number RB1610312; this can also be used to freely access raw neutron data via the ISIS-ICAT system. OSH thanks STFC (ISIS studentship agreement 3578) and the EPSRC Centre for Doctoral Training in Sustainable Chemical Technologies (EP/L016354/1) for PhD funding. The authors acknowledge Ronak Kakadiya for assisting in UV-vis spectroscopy measurements. The authors thank ISIS Neutron & Muon Source for access to NIMROD under experiment number RB1610312; this can also be used to freely access raw neutron data via the ISIS-ICAT system. OSH thanks STFC (ISIS studentship agreement 3578) and the EPSRC Centre for Doctoral Training in Sustainable Chemical Technologies (EP/L016354/1) for PhD funding. The authors acknowledge Ronak Kakadiya for assisting in UV–vis spectroscopy measurements.

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10.1021/acs.inorgchem.3c02205Licence: CC BY

Cite this

@article{6f93f53274664f2798bcefb6b17cae3f,

title = "Trace water changes metal ion speciation in deep eutectic solvents: Ce3+ solvation and nanoscale water clustering in choline chloride-urea-water mixtures",

abstract = "Eutectic mixtures of choline chloride, urea, and water in deep eutectic solvent (DES)/water molar hydration ratios (w) of 2, 5, and 10, with dissolved cerium salt, were measured using neutron diffraction with isotopic substitution. Structures were modeled using empirical potential structure refinement (EPSR). Ce3+ was found to form highly charged complexes with a mean coordination number between 7 and 8, with the shell containing mostly chloride, followed by water. The shell composition is strongly affected by the molar ratio of dilution, as opposed to the mass or volume fraction, due to the high affinity of Cl– and H2O ligands that displace less favorable interactions with ligands such as urea and choline. The presence of Ce3+ salt disrupted the bulk DES structure slightly, making it more electrolyte-like. The measured coordination shell of choline showed significant discrepancies from the statistical noninteracting distribution, highlighting the nonideality of the blend. Cluster analysis revealed the trace presence of percolating water clusters (25 ≥ n ≥ 2) in solvent compositions of 5 and 10w for the first time.",

author = "Oliver Hammond and Bathke, \{Elly Kim\} and Bowron, \{Daniel T.\} and Edler, \{Karen J.\}",

note = "Funders: Engineering and Physical Sciences Research Council - EP/L016354/1; ISIS Neutron and Muon Source - 3578 Funding Information: The authors thank ISIS Neutron \& Muon Source for access to NIMROD under experiment number RB1610312; this can also be used to freely access raw neutron data via the ISIS-ICAT system. OSH thanks STFC (ISIS studentship agreement 3578) and the EPSRC Centre for Doctoral Training in Sustainable Chemical Technologies (EP/L016354/1) for PhD funding. The authors acknowledge Ronak Kakadiya for assisting in UV–vis spectroscopy measurements. ",

year = "2023",

month = nov,

day = "6",

doi = "10.1021/acs.inorgchem.3c02205",

language = "English",

volume = "62",

pages = "18069–18078",

journal = "Inorganic Chemistry",

issn = "0020-1669",

publisher = "American Chemical Society",

number = "44",

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AU - Hammond, Oliver

AU - Bathke, Elly Kim

AU - Bowron, Daniel T.

AU - Edler, Karen J.

N1 - Funders: Engineering and Physical Sciences Research Council - EP/L016354/1; ISIS Neutron and Muon Source - 3578 Funding Information: The authors thank ISIS Neutron & Muon Source for access to NIMROD under experiment number RB1610312; this can also be used to freely access raw neutron data via the ISIS-ICAT system. OSH thanks STFC (ISIS studentship agreement 3578) and the EPSRC Centre for Doctoral Training in Sustainable Chemical Technologies (EP/L016354/1) for PhD funding. The authors acknowledge Ronak Kakadiya for assisting in UV–vis spectroscopy measurements.

PY - 2023/11/6

Y1 - 2023/11/6

N2 - Eutectic mixtures of choline chloride, urea, and water in deep eutectic solvent (DES)/water molar hydration ratios (w) of 2, 5, and 10, with dissolved cerium salt, were measured using neutron diffraction with isotopic substitution. Structures were modeled using empirical potential structure refinement (EPSR). Ce3+ was found to form highly charged complexes with a mean coordination number between 7 and 8, with the shell containing mostly chloride, followed by water. The shell composition is strongly affected by the molar ratio of dilution, as opposed to the mass or volume fraction, due to the high affinity of Cl– and H2O ligands that displace less favorable interactions with ligands such as urea and choline. The presence of Ce3+ salt disrupted the bulk DES structure slightly, making it more electrolyte-like. The measured coordination shell of choline showed significant discrepancies from the statistical noninteracting distribution, highlighting the nonideality of the blend. Cluster analysis revealed the trace presence of percolating water clusters (25 ≥ n ≥ 2) in solvent compositions of 5 and 10w for the first time.

AB - Eutectic mixtures of choline chloride, urea, and water in deep eutectic solvent (DES)/water molar hydration ratios (w) of 2, 5, and 10, with dissolved cerium salt, were measured using neutron diffraction with isotopic substitution. Structures were modeled using empirical potential structure refinement (EPSR). Ce3+ was found to form highly charged complexes with a mean coordination number between 7 and 8, with the shell containing mostly chloride, followed by water. The shell composition is strongly affected by the molar ratio of dilution, as opposed to the mass or volume fraction, due to the high affinity of Cl– and H2O ligands that displace less favorable interactions with ligands such as urea and choline. The presence of Ce3+ salt disrupted the bulk DES structure slightly, making it more electrolyte-like. The measured coordination shell of choline showed significant discrepancies from the statistical noninteracting distribution, highlighting the nonideality of the blend. Cluster analysis revealed the trace presence of percolating water clusters (25 ≥ n ≥ 2) in solvent compositions of 5 and 10w for the first time.

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