Reactive Behaviour of Platinum(II) Salts with Ethylenediamine in Sustainable Water/Choline Chloride-Based Deep Eutectic Solvents Mixtures

Deep eutectic solvents (DESs) are environmentally friendly solvents formed by combining hydrogen bond donors and acceptors, resulting in a eutectic mixture with a lower melting point than the individual components. While there is extensive research on the electrochemical synthesis of platinum nanopa...

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Main Authors: Nicola Garofalo, Francesco Messa, Alessandra Barbanente, Francesco Paolo Fanizzi, Antonio Salomone, Nicola Margiotta, Paride Papadia
Format: Article
Language:English
Published: MDPI AG 2025-04-01
Series:Molecules
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Online Access:https://www.mdpi.com/1420-3049/30/9/1890
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author Nicola Garofalo
Francesco Messa
Alessandra Barbanente
Francesco Paolo Fanizzi
Antonio Salomone
Nicola Margiotta
Paride Papadia
author_facet Nicola Garofalo
Francesco Messa
Alessandra Barbanente
Francesco Paolo Fanizzi
Antonio Salomone
Nicola Margiotta
Paride Papadia
author_sort Nicola Garofalo
collection DOAJ
description Deep eutectic solvents (DESs) are environmentally friendly solvents formed by combining hydrogen bond donors and acceptors, resulting in a eutectic mixture with a lower melting point than the individual components. While there is extensive research on the electrochemical synthesis of platinum nanoparticles in DESs, to the best of our knowledge, there are no studies on the chemical reactivity of platinum(II) complexes in these systems. This study investigates the simple model reaction between K<sub>2</sub>PtCl<sub>4</sub> and ethylenediamine (<i>en</i>), exploring the behaviour in DES environment, to optimize the synthesis of simple cisplatin-like platinum compounds with the potential objective of improving the traditional methods, decreasing the number of steps required for obtaining target compounds and reducing chemical waste. The reactions were performed in two hydrophilic DESs: choline chloride:glycerol 1:2 (glyceline, GL) and choline chloride:ethylene glycol 1:2 (ethaline, EG). The experiments, conducted in a 70% (<i>v</i>/<i>v</i>) DES and 30% 1:1 H<sub>2</sub>O/D<sub>2</sub>O mixture to allow for direct NMR analysis, revealed that <i>en</i> quickly formed [PtCl<sub>2</sub>(en)], which further reacted to produce [Pt(en)<sub>2</sub>]Cl<sub>2</sub>. Reaction products were characterised by 1D (<sup>1</sup>H and <sup>195</sup>Pt{<sup>1</sup>H}) and 2D ([<sup>1</sup>H,<sup>13</sup>C]-HSQC and [<sup>1</sup>H,<sup>15</sup>N]-HSQC) NMR experiments. The discolouration of solutions, due to the consumption of K<sub>2</sub>PtCl<sub>4</sub>, and the precipitation of the purple Magnus salt [Pt(en)<sub>2</sub>][PtCl<sub>4</sub>] occurred over time. The main observed difference between the two solvent mixtures was the slower reactivity in glyceline, due to the much higher viscosity of the solution. Diffusion-ordered spectroscopy (DOSY) indicated lower water mobility in DES mixtures than pure water, with the reaction products closely associated with DES molecules.
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spelling doaj-art-bbc25bfcc68b4e66ab94c383d2a2fcf92025-08-20T03:52:58ZengMDPI AGMolecules1420-30492025-04-01309189010.3390/molecules30091890Reactive Behaviour of Platinum(II) Salts with Ethylenediamine in Sustainable Water/Choline Chloride-Based Deep Eutectic Solvents MixturesNicola Garofalo0Francesco Messa1Alessandra Barbanente2Francesco Paolo Fanizzi3Antonio Salomone4Nicola Margiotta5Paride Papadia6Department of Biological and Environmental Sciences and Technologies (DiSTeBA), University of Salento, 73100 Lecce, ItalyDepartment of Biological and Environmental Sciences and Technologies (DiSTeBA), University of Salento, 73100 Lecce, ItalyDipartimento di Chimica, Università degli Studi di Bari Aldo Moro, Via E. Orabona 4, 70125 Bari, ItalyDepartment of Biological and Environmental Sciences and Technologies (DiSTeBA), University of Salento, 73100 Lecce, ItalyDipartimento di Chimica, Università degli Studi di Bari Aldo Moro, Via E. Orabona 4, 70125 Bari, ItalyDipartimento di Chimica, Università degli Studi di Bari Aldo Moro, Via E. Orabona 4, 70125 Bari, ItalyDepartment of Biological and Environmental Sciences and Technologies (DiSTeBA), University of Salento, 73100 Lecce, ItalyDeep eutectic solvents (DESs) are environmentally friendly solvents formed by combining hydrogen bond donors and acceptors, resulting in a eutectic mixture with a lower melting point than the individual components. While there is extensive research on the electrochemical synthesis of platinum nanoparticles in DESs, to the best of our knowledge, there are no studies on the chemical reactivity of platinum(II) complexes in these systems. This study investigates the simple model reaction between K<sub>2</sub>PtCl<sub>4</sub> and ethylenediamine (<i>en</i>), exploring the behaviour in DES environment, to optimize the synthesis of simple cisplatin-like platinum compounds with the potential objective of improving the traditional methods, decreasing the number of steps required for obtaining target compounds and reducing chemical waste. The reactions were performed in two hydrophilic DESs: choline chloride:glycerol 1:2 (glyceline, GL) and choline chloride:ethylene glycol 1:2 (ethaline, EG). The experiments, conducted in a 70% (<i>v</i>/<i>v</i>) DES and 30% 1:1 H<sub>2</sub>O/D<sub>2</sub>O mixture to allow for direct NMR analysis, revealed that <i>en</i> quickly formed [PtCl<sub>2</sub>(en)], which further reacted to produce [Pt(en)<sub>2</sub>]Cl<sub>2</sub>. Reaction products were characterised by 1D (<sup>1</sup>H and <sup>195</sup>Pt{<sup>1</sup>H}) and 2D ([<sup>1</sup>H,<sup>13</sup>C]-HSQC and [<sup>1</sup>H,<sup>15</sup>N]-HSQC) NMR experiments. The discolouration of solutions, due to the consumption of K<sub>2</sub>PtCl<sub>4</sub>, and the precipitation of the purple Magnus salt [Pt(en)<sub>2</sub>][PtCl<sub>4</sub>] occurred over time. The main observed difference between the two solvent mixtures was the slower reactivity in glyceline, due to the much higher viscosity of the solution. Diffusion-ordered spectroscopy (DOSY) indicated lower water mobility in DES mixtures than pure water, with the reaction products closely associated with DES molecules.https://www.mdpi.com/1420-3049/30/9/1890deep eutectic solventscisplatinplatinum(II) complexesDOSY<sup>195</sup>Pt NMR spectroscopy<sup>15</sup>N NMR spectroscopy
spellingShingle Nicola Garofalo
Francesco Messa
Alessandra Barbanente
Francesco Paolo Fanizzi
Antonio Salomone
Nicola Margiotta
Paride Papadia
Reactive Behaviour of Platinum(II) Salts with Ethylenediamine in Sustainable Water/Choline Chloride-Based Deep Eutectic Solvents Mixtures
Molecules
deep eutectic solvents
cisplatin
platinum(II) complexes
DOSY
<sup>195</sup>Pt NMR spectroscopy
<sup>15</sup>N NMR spectroscopy
title Reactive Behaviour of Platinum(II) Salts with Ethylenediamine in Sustainable Water/Choline Chloride-Based Deep Eutectic Solvents Mixtures
title_full Reactive Behaviour of Platinum(II) Salts with Ethylenediamine in Sustainable Water/Choline Chloride-Based Deep Eutectic Solvents Mixtures
title_fullStr Reactive Behaviour of Platinum(II) Salts with Ethylenediamine in Sustainable Water/Choline Chloride-Based Deep Eutectic Solvents Mixtures
title_full_unstemmed Reactive Behaviour of Platinum(II) Salts with Ethylenediamine in Sustainable Water/Choline Chloride-Based Deep Eutectic Solvents Mixtures
title_short Reactive Behaviour of Platinum(II) Salts with Ethylenediamine in Sustainable Water/Choline Chloride-Based Deep Eutectic Solvents Mixtures
title_sort reactive behaviour of platinum ii salts with ethylenediamine in sustainable water choline chloride based deep eutectic solvents mixtures
topic deep eutectic solvents
cisplatin
platinum(II) complexes
DOSY
<sup>195</sup>Pt NMR spectroscopy
<sup>15</sup>N NMR spectroscopy
url https://www.mdpi.com/1420-3049/30/9/1890
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