Defying decomposition: the curious case of choline chloride

Abstract Chemists aim to meet modern sustainability, health, and safety requirements by replacing conventional solvents with deep eutectic solvents (DESs). Through large melting point depressions, DESs may incorporate renewable solids in task-specific liquids. Yet, DES design is complicated by compl...

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Main Authors: Adriaan van den Bruinhorst, Jocasta Avila, Martin Rosenthal, Ange Pellegrino, Manfred Burghammer, Margarida Costa Gomes
Format: Article
Language:English
Published: Nature Portfolio 2023-10-01
Series:Nature Communications
Online Access:https://doi.org/10.1038/s41467-023-42267-6
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author Adriaan van den Bruinhorst
Jocasta Avila
Martin Rosenthal
Ange Pellegrino
Manfred Burghammer
Margarida Costa Gomes
author_facet Adriaan van den Bruinhorst
Jocasta Avila
Martin Rosenthal
Ange Pellegrino
Manfred Burghammer
Margarida Costa Gomes
author_sort Adriaan van den Bruinhorst
collection DOAJ
description Abstract Chemists aim to meet modern sustainability, health, and safety requirements by replacing conventional solvents with deep eutectic solvents (DESs). Through large melting point depressions, DESs may incorporate renewable solids in task-specific liquids. Yet, DES design is complicated by complex molecular interactions and a lack of comprehensive property databases. Even measuring pure component melting properties can be challenging, due to decomposition before melting. Here we overcame the decomposition of the quintessential DES constituent, choline chloride (ChCl). We measured its enthalpy of fusion (13.8 ± 3.0 kJ ⋅ mol) and melting point (687 ± 9 K) by fast scanning calorimetry combined with micro-XRD and high-speed optical microscopy. Our thermodynamically coherent fusion properties identify ChCl as an ionic plastic crystal and demonstrate negative deviations from ideal mixing for ChCl—contradicting previous assumptions. We hypothesise that the plastic crystal nature of ammonium salts governs their resilience to melting; pure or mixed. We show that DESs based on ionic plastic crystals can profit from (1) a low enthalpy of fusion and (2) favourable mixing. Both depress the melting point and can be altered through ion selection. Ionic plastic crystal-based DESs thus offer a platform for task-specific liquids at a broad range of temperatures and compositions.
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spelling doaj.art-015912f73e3c45e3ac10347e4f4754432023-11-20T09:53:21ZengNature PortfolioNature Communications2041-17232023-10-011411710.1038/s41467-023-42267-6Defying decomposition: the curious case of choline chlorideAdriaan van den Bruinhorst0Jocasta Avila1Martin Rosenthal2Ange Pellegrino3Manfred Burghammer4Margarida Costa Gomes5École Normale Supérieure de Lyon and CNRS, Laboratoire de Chimie, Ionic Liquids GroupÉcole Normale Supérieure de Lyon and CNRS, Laboratoire de Chimie, Ionic Liquids GroupDepartment of Chemistry, KU LeuvenÉcole Normale Supérieure de Lyon and CNRS, Laboratoire de Chimie, Ionic Liquids GroupESRF, The European SynchrotronÉcole Normale Supérieure de Lyon and CNRS, Laboratoire de Chimie, Ionic Liquids GroupAbstract Chemists aim to meet modern sustainability, health, and safety requirements by replacing conventional solvents with deep eutectic solvents (DESs). Through large melting point depressions, DESs may incorporate renewable solids in task-specific liquids. Yet, DES design is complicated by complex molecular interactions and a lack of comprehensive property databases. Even measuring pure component melting properties can be challenging, due to decomposition before melting. Here we overcame the decomposition of the quintessential DES constituent, choline chloride (ChCl). We measured its enthalpy of fusion (13.8 ± 3.0 kJ ⋅ mol) and melting point (687 ± 9 K) by fast scanning calorimetry combined with micro-XRD and high-speed optical microscopy. Our thermodynamically coherent fusion properties identify ChCl as an ionic plastic crystal and demonstrate negative deviations from ideal mixing for ChCl—contradicting previous assumptions. We hypothesise that the plastic crystal nature of ammonium salts governs their resilience to melting; pure or mixed. We show that DESs based on ionic plastic crystals can profit from (1) a low enthalpy of fusion and (2) favourable mixing. Both depress the melting point and can be altered through ion selection. Ionic plastic crystal-based DESs thus offer a platform for task-specific liquids at a broad range of temperatures and compositions.https://doi.org/10.1038/s41467-023-42267-6
spellingShingle Adriaan van den Bruinhorst
Jocasta Avila
Martin Rosenthal
Ange Pellegrino
Manfred Burghammer
Margarida Costa Gomes
Defying decomposition: the curious case of choline chloride
Nature Communications
title Defying decomposition: the curious case of choline chloride
title_full Defying decomposition: the curious case of choline chloride
title_fullStr Defying decomposition: the curious case of choline chloride
title_full_unstemmed Defying decomposition: the curious case of choline chloride
title_short Defying decomposition: the curious case of choline chloride
title_sort defying decomposition the curious case of choline chloride
url https://doi.org/10.1038/s41467-023-42267-6
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