Physico-Chemical Characterization of Amino Acid-Based Deep Eutectic Solvents
Abstract
:1. Introduction
2. Results and Discussion
2.1. Formation of Homogenous Liquids
2.2. Thermal Behavior
2.3. Viscosity
2.4. Refractive Index
2.5. Surface Tension
3. Materials and Methods
3.1. Synthesis
3.2. Characterization
4. Conclusions
Supplementary Materials
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Conflicts of Interest
References
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Amino Acid | HBD | Ratio | Water (wt%) | Thermal Behavior (°C) | Viscosity (Pa·s) | RI (±0.003) | Surface Tension (mN/m) |
---|---|---|---|---|---|---|---|
Lysine | Glycerol | 1:3 | 1.3 | Glass: −74 ± 1 | 1.9 ± 0.2 | 1.485 | 106 ± 5 |
1:4 | 1 | Glass: −75 ± 1 | 1.7 ± 0.1 | 1.482 | 97 ± 10 | ||
1:4.5 | 0.9 | Glass: −76 ± 1 | 1.4 ± 0.1 | 1.481 | 91 ± 4 | ||
Ethylene Glycol | 1:4 | 1.1 | Melt: −22 ± 1 Glass: −110 ± 1 | 0.03 ± 0.001 | 1.446 | 60 ± 6 | |
1:5 | 0.87 | Melt: −21 ± 1 Glass: −112 ± 1 | 0.027 ± 0.001 | 1.443 | 54 ± 2 | ||
Arginine | Glycerol | 1:3 | 10 | Glass: −72 ± 3 | 2.0 ± 0.07 | 1.493 | 115 ± 2 |
1:4.5 | 0.2 | Glass: −74 ± 1 | 2.2 ± 0.1 | 1.486 | 117 ± 2 | ||
Ethylene Glycol | 1:4 | 0.3 | Melt: −21 ± 1 Glass: −110 ± 1 | 0.043 ± 0.002 | 1.450 | 60 ± 5 | |
1:5 | 0.3 | Melt: −2 ± 1 Glass: −111 ± 1 | 0.035 ± 0.001 | 1.449 | 52.8 ± 0.3 | ||
Serine | Glycerol | 1:4.5 | 23 | Glass: −95 ± 1 | 0.058 ± 0.002 | 1.449 | 63.8 ± 0.4 |
Ethylene Glycol | 1:5 | 29 A | Glass: −122 ± 1 | 0.011 ± 0.003 | 1.414 | 54.5 ± 0.1 | |
Glycine | Glycerol | 1:4.5 | 21 A | Glass: −94 ± 1 | 0.061 ± 0.004 | 1.450 | 69.6 ± 0.2 |
Mixture | Molar Ratio | Scaled Molar Excess Gibbs Free Energy | Maximum Melting Point to Meet DES Requirement (°C) |
---|---|---|---|
Lysine–Glycerol | 1:3 | No melting point in DSC | 13 |
1:4 | No melting point in DSC | 10 | |
1:4.5 | No melting point in DSC | 10 | |
Lysine–Ethylene Glycol | 1:4 | −0.4 | −15 |
1:5 | −0.4 | −20 | |
Arginine–Glycerol | 1:4.5 | No melting point in DSC | 17 |
Arginine–Ethylene Glycol | 1:4 | −2.2 | −4 * |
1:5 | −1.8 | −10 * |
Amino Acid | HBD | Ratio | Result |
---|---|---|---|
L-Proline | Glycerol | 1:3 | Homogenous yellow/brown liquid |
Ethylene Glycol | 1:4 | Homogenous yellow liquid | |
L-Alanine | Glycerol | 1:3 | Precipitated crystals, even with >50 wt% water. |
Ethylene Glycol | 1:4 | Precipitated crystals, even with >50 wt% water. | |
L-Lysine | Glycerol | 1:3 | Homogenous yellow liquid |
1:4 | Homogenous yellow liquid | ||
1:4.5 | Homogenous yellow liquid | ||
Ethylene Glycol | 1:4 | Homogenous yellow liquid | |
1:5 | Homogenous yellow liquid | ||
L-Methionine | Glycerol | 1:3 | Precipitated crystals, even with >50 wt% water. |
Ethylene Glycol | 1:4 | Precipitated crystals, even with >50 wt% water. | |
L-Threonine | Glycerol | 1:3 | Precipitated crystals, even with >50 wt% water. |
Ethylene Glycol | 1:4 | Precipitated crystals, even with >50 wt% water. | |
L-Valine | Glycerol | 1:3 | Precipitated crystals, even with >50 wt% water. |
Ethylene Glycol | 1:4 | Precipitated crystals, even with >50 wt% water. | |
L-Tryptophan | Glycerol | 1:3 | Precipitated crystals, even with >50 wt% water. |
Ethylene Glycol | 1:4 | Precipitated crystals, even with >50 wt% water. | |
L-Tyrosine | Glycerol | 1:3 | Precipitated crystals, even with >50 wt% water. |
Ethylene Glycol | 1:4 | Precipitated crystals, even with >50 wt% water. | |
L-Phenylalanine | Glycerol | 1:3 | Precipitated crystals, even with >50 wt% water. |
Ethylene Glycol | 1:4 | Precipitated crystals, even with >50 wt% water. | |
L-Leucine | Glycerol | 1:3 | Precipitated crystals, even with >50 wt% water. |
Ethylene Glycol | 1:4 | Precipitated crystals, even with >50 wt% water. | |
L-Glutamic Acid | Glycerol | 1:3 | Precipitated crystals, even with >50 wt% water. |
Ethylene Glycol | 1:4 | Precipitated crystals, even with >50 wt% water. | |
L-Glutamine | Glycerol | 1:3 | Precipitated crystals, even with >50 wt% water. |
Ethylene Glycol | 1:4 | Precipitated crystals, even with >50 wt% water. | |
Glycine | Glycerol | 1:3 | Precipitated crystals, even with >50 wt% water. |
1:4.5 | Homogenous mixture at 21 wt% water * | ||
Ethylene Glycol | 1:4 | Precipitated crystals, even with >50 wt% water. | |
L-Histidine | Glycerol | 1:3 | Precipitated crystals, even with >50 wt% water. |
Ethylene Glycol | 1:4 | Precipitated crystals, even with >50 wt% water. | |
L-Isoleucine | Glycerol | 1:3 | Precipitated crystals, even with >50 wt% water. |
Ethylene Glycol | 1:4 | Precipitated crystals, even with >50 wt% water. | |
L-Cystine | Glycerol | 1:3 | Precipitated crystals, even with >50 wt% water. |
Ethylene Glycol | 1:4 | Precipitated crystals, even with >50 wt% water. | |
L-Cysteine | Glycerol | 1:3 | Precipitated crystals, even with >50 wt% water. |
Ethylene Glycol | 1:4 | Precipitated crystals, even with >50 wt% water. | |
L-Asparagine | Glycerol | 1:3 | Precipitated crystals, even with >50 wt% water. |
Ethylene Glycol | 1:4 | Precipitated crystals, even with >50 wt% water. | |
L-Aspartic Acid | Glycerol | 1:3 | Precipitated crystals, even with >50 wt% water. |
Ethylene Glycol | 1:4 | Precipitated crystals, even with >50 wt% water. | |
L-Ascorbic Acid | Glycerol | 1:3 | Precipitated crystals, even with >50 wt% water. |
Ethylene Glycol | 1:4 | Precipitated crystals, even with >50 wt% water. | |
L-Arginine | Glycerol | 1:3 | Formed a homogenous mixture at 10 wt% water |
1:4.5 | Homogenous, slightly yellow liquid | ||
Ethylene Glycol | 1:4 | Homogenous, mostly clear liquid | |
1:5 | Homogenous, slightly yellow liquid | ||
L-Serine | Glycerol | 1:3 | Homogenous mixture at 49 wt% water |
1:4.5 | Homogenous mixture at 23 wt% water * | ||
Ethylene Glycol | 1:4 | Precipitated crystals, even with >50 wt% water. | |
1:5 | Homogenous mixture at 29 wt% water * |
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Bryant, S.J.; Bryant, G.; Drummond, C.J.; Greaves, T.L. Physico-Chemical Characterization of Amino Acid-Based Deep Eutectic Solvents. Molecules 2025, 30, 818. https://doi.org/10.3390/molecules30040818
Bryant SJ, Bryant G, Drummond CJ, Greaves TL. Physico-Chemical Characterization of Amino Acid-Based Deep Eutectic Solvents. Molecules. 2025; 30(4):818. https://doi.org/10.3390/molecules30040818
Chicago/Turabian StyleBryant, Saffron J., Gary Bryant, Calum J. Drummond, and Tamar L. Greaves. 2025. "Physico-Chemical Characterization of Amino Acid-Based Deep Eutectic Solvents" Molecules 30, no. 4: 818. https://doi.org/10.3390/molecules30040818
APA StyleBryant, S. J., Bryant, G., Drummond, C. J., & Greaves, T. L. (2025). Physico-Chemical Characterization of Amino Acid-Based Deep Eutectic Solvents. Molecules, 30(4), 818. https://doi.org/10.3390/molecules30040818