Choline Chloride-urea Research Articles

Choline Chloride Urea Effect on Liquid–Liquid Equilibria of 5-Hydroxymethylfurfural–Water–Organic Solvent Systems in the Absence and Presence of Sodium Chloride

Deep eutectic solvent (DES) has demonstrated its ability to improve the yield and selectivity in the 5-hydroxymethylfurfural (HMF) production process. Liquid–liquid extraction is a beneficial proce...

Effect of mono-vacant defects on the adsorption properties of deep eutectic solvents onto hexagonal boron-nitride nanoflakes

Hexagonal boron nitride is a promising material for a variety of electronic, optical, and material science applications. Both the synthesis of the material through exfoliation, and its various applications almost inevitably require its solvation. Deep eutectic solvents (DES) are extremely useful solvents for these types of applications due to their non-volatility, inflammability, biocompatibility, and reasonable cost. There are many different deep eutectic solvents available, and their suitability for any given application is particularly dependent on the specific of their structure. DES have been examined computationally for use with boron nitride, but these calculations use idealized, perfect boron nitride sheets instead of the more realistic, defect-containing systems. In this report, we investigated four DESs with two experimentally observed defective boron nitride, one with a single boron vacancy, the other with a single nitrogen vacancy. All DESs bound with higher affinity to the defective boron nitride than to the pristine surface. Charge transfer was minimal in all cases although the surfaces tended to donate electron density to the solvents. The interactions between the solvents and the surfaces are primarily non-covalent although in several cases natural bond order analysis indicates a partial covalent interaction that helps explain the higher-than-expected affinity for particular DES. The DESs have little effect on the predicted optical behaviour of the pristine boron nitride but do significantly change the adsorption spectrum of the defective boron nitride nanoflakes; the effect on bulk material might be limited. Together these results suggest that the choice of DES can either be made to limit any effect on the properties of the material (urea-choline chloride) or to affect the optical and electronic nature of the material (benzoic acid-choline chloride).

Versatile Ionic Gel Driven by Dual Hydrogen Bond Networks: Toward Advanced Lubrication and Self-Healing

From one to more, the same raw materials giving rise to multifarious products is one of the goals of researchers to pursue industrial efficiency. Herein, we designed a formula (controlling the content of the matrix) to prepare two functional ionic gels, integrating the excellent lubrication, thermal conductivity, and self-healing ability to meet different industrial demands of the lubrication and biomedical fields. Deep eutectic solvents (DESs) of urea/choline chloride (UCC) and glycerol/choline chloride (GCC) were locked in polyacrylamide (PAM) ionic gel formed by acrylamide (AM) and a photoinitiator by free-radical polymerization. The unique dual hydrogen bond network in the ionic gel causes the material to exhibit a low wear rate, which can effectively reduce the wear of metal contact. With the addition of PAM, the ionic gel has excellent mechanical strength and good recovery performance. Unexpectedly, this dense hydrogen bond network enhances thermal conductivity by optimizing phonon and electron transfer. The versatile ionic gel has a good application prospect as a substitute for industrial lubricants and medical device materials.

Green synthesis, cytotoxicity and antimicrobial activities of some new pyrazolines, pyrimidines and naphthyridines based on 1,3-di(thien-2-yl)prop-2-en-1-one using choline chloride-urea mixture as a deep eutectic solvent

An efficient and facile green synthesis of chalcone derivatives 1a-d was achieved by treatment of aromatic aldehydes with 2-acetylthiophene in the presence of choline chloride-urea mixture as a deep eutectic solvent. Chalcone 1a was used as a reactive key precursor to design a series of bio-active heterocycles such as pyrimidine, pyrazoline, pyridine, pyridopyrimidine and naphthyridine. The Structural formula of derivatives were confirmed and characterized by their elemental analyses and spectral data (IR, MS, 1H NMR, 13C NMR). In addition, the synthesized derivatives were evaluated for their antimicrobial activities, it was found that compounds 3, 8 and 9a exhibited potent antifungal activity in comparison with the standard drug. Cytotoxicity against breast cancer (MCF7) was screened also and most compounds showed low to moderate activity. The results of the viral screening against HBV of selected compounds indicated that compounds (9b, 15), 8, (3, 6), and 5 showed moderate viral replication inhibition.

Electrochemical immunosensor for determination of cardiac troponin I using two-dimensional metal-organic framework/Fe3O4–COOH nanosheet composites loaded with thionine and pCTAB/DES modified electrode

Cardiac troponin-I (CTnI) is one of the most popular biomarkers which can be utilized for the diagnosis and control of acute myocardial infarction in clinical practice. Here, a sandwich-type electrochemical immunosensor has been established using the zinc-based metal-organic framework/Fe3O4–COOH/thionine labeled anti-CTnI monoclonal antibody (Ab1-Zn-MOF/Fe3O4–COOH/Thi) nanocomposite as signaling molecule and a polymer film of cetyltrimethylammonium bromide (pCTAB) in the presence of choline chloride-urea deep eutectic solvent (DES) and anti-CTnI polyclonal antibody (Ab2) as immobilization substance of detecting surface. The porous ultrathin layers of Zn-MOF nanosheets successfully prepare a well-defined structure for Fe3O4–COOH electrocatalyst and Thi within a certain two dimensional (2D) regions, which enhances electrochemical reduction of Thi. The Ab1-Zn-MOF/Fe3O4–COOH/Thi nanocomposites were introduced to CTnI in the specimen and on the surface of pCTAB/DES-Au-SPE quantitative determination of CTnI was achieved using differential pulse voltammetry after sandwiching the CTnI target between Ab1-nanocomposite and Ab2 which was encapsulated into the pCTAB/DES-Au-SPE. This immunosensor indicated the appropriate assay performance for CTnI with the detection range of 0.04 ng mL−1 to 50 ng mL−1 and the limit of detection of 0.0009 ng mL−1. This study provides convenient plan for sensitive detection of bioanalytes and opens a path for the establishment of user-friendly and cost-effective device.

Eco-friendly Process to Degum Flax Roving with Deep Eutectic Solvent and Microbial Treatment

ABSTRACT Flax is an economically important fiber crop, however, it requires degumming to yield usable fibers. The degumming process of flax roving is a key step in flax processing and production. In this study, deep eutectic solvent (DES; choline chloride–urea) pretreatment was combined with microbial treatment to develop an ecofriendly and effective degumming method for flax roving. The optimal conditions for DES pretreatment (100°C for 120 min with 90% DES) were obtained through orthogonal tests. DES combine microbial treatment could effectively remove gum from the flax fibers. The flax roving fibers were characterized by chemical analyses, scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffractometry, and thermogravimetric analysis. Compared with fibers treated with microbes alone, flax roving fibers subjected to DES combine microbial treatment showed better breaking tenacity (16.77 cN/tex) and average pectin, hemicellulose, and lignin removal rates of approximately 86.4%, 26.7%, and 55.1%, respectively. NMR revealed that the composition of DES was not damaged during pretreatment, which means the bulk solution could be reused. This research showed that DES combine microbial treatment is feasible and effective method for flax roving degumming.

Vapor pressures and vapor phase compositions of choline chloride urea and choline chloride ethylene glycol deep eutectic solvents from molecular simulation.

Despite the widespread acknowledgment that deep eutectic solvents (DESs) have negligible vapor pressures, very few studies in which the vapor pressures of these solvents are measured or computed are available. Similarly, the vapor phase composition is known for only a few DESs. In this study, for the first time, the vapor pressures and vapor phase compositions of choline chloride urea (ChClU) and choline chloride ethylene glycol (ChClEg) DESs are computed using Monte Carlo simulations. The partial pressures of the DES components were obtained from liquid and vapor phase excess Gibbs energies, computed using thermodynamic integration. The enthalpies of vaporization were computed from the obtained vapor pressures, and the results were in reasonable agreement with the few available experimental data in the literature. It was found that the vapor phases of both DESs were dominated by the most volatile component (hydrogen bond donor, HBD, i.e., urea or ethylene glycol), i.e., 100% HBD in ChClEg and 88%-93% HBD in ChClU. Higher vapor pressures were observed for ChClEg compared to ChClU due to the higher volatility of ethylene glycol compared to urea. The influence of the liquid composition of the DESs on the computed properties was studied by considering different mole fractions (i.e., 0.6, 0.67, and 0.75) of the HBD. Except for the partial pressure of ethylene glycol in ChClEg, all the computed partial pressures and enthalpies of vaporization showed insensitivity toward the liquid composition. The activity coefficient of ethylene glycol in ChClEg was computed at different liquid phase mole fractions, showing negative deviations from Raoult's law.

Deep eutectic solvent mediated nanostructured copper oxide as a positive electrode material for hybrid supercapacitor device

Metal oxides have received significant attention for various applications over the last few decades due to their better structural, morphological, and electrochemical properties. Herein, a green approach is introduced for the synthesis of nanostructured CuO using a choline chloride urea (CCU)-based deep eutectic solvent (DES) method. The effects of varying reaction times upon the surface morphological and electrochemical properties of the CuO are examined. In particular, the CuO sample obtained at 12 h of reaction time is shown to exhibit a porous nanograin-like surface morphology with a grain size of less than 20 nm and an excellent specific capacity (Cs) of 176 mAh g−1 at a scan rate of 5 mV s−1. Further, the practicability of the CuO-based electrode is demonstrated by the fabrication of a CuO//activated carbon (AC) hybrid supercapacitor device. The CuO//AC shows a noteworthy electrochemical performance, with a Cs of 82 mAh g−1, specific energy of 35.86 Wh kg−1, a specific power of 2017 W kg−1, and a long-term stability of 98% after 2000 cycles.

Properties and Kinetics of Selective Zinc Leaching with Choline Chloride and Urea

A choline chloride-urea (ChCl-urea) deep eutectic solvent (DES) was used to experimentally investigate the secondary recovery of zinc from zinc-bearing dust sludge via a leaching process. The effects of varying the liquid–solid ratio, leaching temperature, stirring speed, and leaching time on the zinc leaching efficiency were determined, and the optimum values of these parameters were found to be 15:1, 90 °C, 400 rpm, and 600 min, respectively, at which a leaching efficiency of 86.87% was achieved. XRF and EDS analyses confirmed that the zinc content in the sludge decreased noticeably after leaching, while those of other elements did not, indicating the selective and efficient leaching of zinc. A study of the leaching kinetics showed that the reaction conforms to the nuclear shrinkage model without solid product layer formation, and the calculated apparent activation energy is 22.16 kJ/mol.

Multifunctional supramolecular eutectogels for self-healable conductive materials and interface lubrication

Supramolecular eutectogels formed by self-assembly of low molecular weight gelators in deep eutectic solvents provides a new prospect for the development of soft ionic materials. In this study, we had developed a series of D-glucose acetal gelators (DAn), which showed excellent gelation ability in DESs based on choline chloride (ChCl) and polyols or urea. Rheology showed that the structure of the gelators and the type of DESs have significant effects on the mechanical strength and thixotropy of the gels. Remarkably, the eutectogel formed by DA10 in ChCl/Glycerol showed high transparency, self-healing, load-bearing, and injectability. The results obtained from scanning electron microscopy and X-ray diffraction suggested that DA10 adopted hexagonal stacking to form a fibrous morphology in ChCl/ monoethylene and ChCl/ Glycerol, while sheet-like structure was formed by lamellar packing of DA10 in ChCl/Urea. Moreover, the high ionic conductivity coupled with self-healing property of eutectogel make it a potential smart conductive material. The eutectogels exhibited remarkable lubricating properties on steel interface due to their excellent self-healing, creep recovery, and corrosion resistance properties. Overall, this research on the structure–function relationship of supramolecular eutectogels and their applications in conductive materials and interfacial lubrication have great guiding significance for the development of versatile supramolecular eutectogels in the future.

Microwave- and ultrasound-assisted extraction of capsaicin from Capsicum annuum using deep eutectic solvents

ABSTRACT Methods exist to extract capsaicin from chili (Capsicum annuum L.), but they have poor yield and are hazardous to the environment. The objective of the study was to develop a process for extraction of capsaicin from chili that is more efficient and bio-rationale. Two deep eutectic solvents (DES), choline chloride-urea (CCU) and choline chloride-glycerol (CCG), were used for extraction with MAE (microwave-assisted extraction) and UAE (ultrasound-assisted extraction). In MAE, the highest yield in both solvents was at 600 W and solvent-solid ratio 30 mL∙g−1 for CCU 18.88 mg∙g−1 and for CCG 14.49 mg∙g−1. In UAE, the highest yield in both solvents was at 50°C and solvent-solid ratio 100 mL∙g−1 (2.77 for CCU and 2.59 mg∙g−1 for CCG). The CCU (1:2) was an efficient solvent for extraction of capsaicin from chili and MAE was more efficient than UAE (ultrasound-assisted extraction). The results provide a new method to obtain capsaicin efficiently from C. annuum.

High-efficiency and recyclable ramie cellulose fiber degumming enabled by deep eutectic solvent

Gummy components in raw ramie are required to be removed to extract cellulose fibers. However, current common degumming techniques are largely limited because of long procedures, heavy environmental pollution, high energy consumption, and insufficient efficiency. Here, deep eutectic solvent (DES) was explored to ramie cellulose fiber degumming without combining any further treatment. Three DESs, namely, choline chloride-urea (CU), choline chloride-imidazole (CI), and ethylamine hydrochloride-ethylene glycol (EE), were demonstrated to be capable of removing non-cellulose impurities in 2 h in one-step boiling process without damaging cellulose structure. The purified fibers were systematically characterized in terms of mechanical properties and chemical constitutions. Results showed that the DES can effectively remove most non-cellulosic materials from raw ramie. The CU treated fibers exhibited a higher tenacity (6.51 cN/dtex) and lower residual gum content (3.76 %), which was nearly in the same level of traditional alkaline (TAL) treated fibers. The fibers degummed with CI showed the highest break elongation (3.30 %) and relatively good tenacity (5.50 cN/dtex). Comparatively, the EE treated fibers exhibited the poorest tenacity (3.05 cN/dtex) despite of the lowest residual gum content (3.15 %). Besides, the DES was reusable and recyclable, which can be repeatedly used for many times. The cellulose fibers achieved high tenacity and low residual gum content after the fifth cycles’ treatment with DES, which still met the requirement of downstream applications. Finally, the lignin in degumming waste solution was further fractionated, and the purity of the extracted lignin was proved to be 9.54 %. Featured with high efficiency, short process, less chemical and energy usage, high quality fibers as well as easy reutilization of solvent, this approach is of great potential for cellulose fiber isolation.

Effect of some choline based deep eutectic solvents on volumetric and ultrasonic properties of gabapentin drug in water at T = (288.15 to 318.15) K

A key part of the drug preparation process is the optimization of molecular interactions between drugs and solvents. Thermodynamic properties provides complete information on interactions and the selection of suitable solvents for various pharmaceutical processes. Especially, the investigation of antiepileptic drugs in aqueous solutions has been a subject of interest because they employ their effect by interaction with biological membranes. In this study, the density and speed of sound for the gabapentin (GBP) in aqueous deep eutectic solvents (DESs), (choline chloride/ethylene glycol (ChCl/EG), choline chloride/glycerol (ChCl/Gly), and choline chloride/urea (ChCl/U)) as novel category of green solvents were measured at temperature range 288.15 K to 318.15 K. The apparent molar volumes Vφ, apparent molar isobaric expansion Eφ0, Hepler’s constant and apparent molar isentropic compressibility κφ were calculated from the density and speed of sound data. Findings show that Vφ values are higher for binary systems compared to ternary systems. The order of Vφ values for aqueous DESs solutions are as follows: ChCl/EG > ChCl/U > ChCl/Gly. The standard partial molar volume Vφ0 and partial molar isentropic compressibility κφ0 were obtained by using the Redlich-Meyer equation. The obtained results for the Vφ0 quantity indicate a strong interaction between the GBP drug and the ChCl/Gly. Finally, using the results of Eφ0, it is understood that GBP has acted as a structure maker in the presence of all DESs.

Electrochemical Behavior and Electronucleation of Copper Nanoparticles from CuCl2·2H2O Using a Choline Chloride-Urea Eutectic Mixture

This work presents a thorough study on the early stage of copper electrodeposition from a choline chloride-urea deep eutectic solvent (DES). Determination of possible species in DES containing Cu2+ ions as the electrolytes has been performed using UV-Vis measurements. Kinetic and thermodynamic aspects of copper electrodeposition on glassy carbon electrode from DES were thoroughly investigated using cyclic voltammetry (CV) and chronoamperometry (CA). Both results from CA and CV have demonstrated that the copper electrodeposition could be performed directly from DES containing a small amount of water by the single potentiostatic step technique. Theoretical approach confirmed that the direct electronucleation of copper nanoparticles in the DES can be described by a model with two contributions, namely, (i) adsorption process and (ii) a three-dimensional (3D) nucleation and diffusion-controlled growth of copper nuclei, to the total current density transients. Kinetic parameters are important for controlling morphology and chemical composition of the obtained nanoparticles, which are verified by surface characterization techniques such as SEM and EDS.

Carbon Capture from Biogas by Deep Eutectic Solvents: A COSMO Study to Evaluate the Effect of Impurities on Solubility and Selectivity

Deep eutectic solvents (DES) are compounds of a hydrogen bond donor (HBD) and a hydrogen bond acceptor (HBA) that contain a depressed melting point compared to their individual constituents. DES have been studied for their use as carbon capture media and biogas upgrading. However, contaminants’ presence in biogas might affect the carbon capture by DES. In this study, conductor-like screening model for real solvents (COSMO-RS) was used to determine the effect of temperature, pressure, and selective contaminants on five DES’ namely, choline chloride-urea, choline chloride-ethylene glycol, tetra butyl ammonium chloride-ethylene glycol, tetra butyl ammonium bromide-decanoic acid, and tetra octyl ammonium chloride-decanoic acid. Impurities studied in this paper are hydrogen sulfide, ammonia, water, nitrogen, octamethyltrisiloxane, and decamethylcyclopentasiloxane. At infinite dilution, CO2 solubility dependence upon temperature in each DES was examined by means of Henry’s Law constants. Next, the systems were modeled from infinite dilution to equilibrium using the modified Raoults’ Law, where CO2 solubility dependence upon pressure was examined. Finally, solubility of CO2 and CH4 in the various DES were explored with the presence of varying mole percent of selective contaminants. Among the parameters studied, it was found that the HBD of the solvent is the most determinant factor for the effectiveness of CO2 solubility. Other factors affecting the solubility are alkyl chain length of the HBA, the associated halogen, and the resulting polarity of the DES. It was also found that choline chloride-urea is the most selective to CO2, but has the lowest CO2 solubility, and is the most polar among other solvents. On the other hand, tetraoctylammonium chloride-decanoic acid is the least selective, has the highest maximum CO2 solubility, is the least polar, and is the least affected by its environment.

How sensitive are physical properties of choline chloride-urea mixtures to composition changes: Molecular dynamics simulations and Kirkwood-Buff theory.

Deep eutectic solvents (DESs) have emerged as a cheaper and greener alternative to conventional organic solvents. Choline chloride (ChCl) mixed with urea at a molar ratio of 1:2 is one of the most common DESs for a wide range of applications such as electrochemistry, material science, and biochemistry. In this study, molecular dynamics simulations are performed to study the effect of urea content on the thermodynamic and transport properties of ChCl and urea mixtures. With increased mole fraction of urea, the number of hydrogen bonds (HBs) between cation-anion and ion-urea decreases, while the number of HBs between urea-urea increases. Radial distribution functions (RDFs) for ChCl-urea and ChCl-ChCl pairs shows a significant decrease as the mole fraction of urea increases. Using the computed RDFs, Kirkwood-Buff Integrals (KBIs) are computed. KBIs show that interactions of urea-urea become stronger, while interactions of urea-ChCl and ChCl-ChCl pairs become slightly weaker with increasing mole fraction of urea. All thermodynamic factors are found larger than one, indicating a non-ideal mixture. Our results also show that self- and collective diffusivities increase, while viscosities decrease with increasing urea content. This is mainly due to the weaker interactions between ions and urea, resulting in enhanced mobilities. Ionic conductivities exhibit a non-monotonic behavior. Up to a mole fraction of 0.5, the ionic conductivities increase with increasing urea content and then reach a plateau.

Polyimide ultrafiltration membrane embedded with reline-functionalized nanosilica for the remediation of pharmaceuticals in water

This study introduces the use of choline chloride-urea (ChCl-U) deep eutectic solvent (DES) in polyimide (PI) ultrafiltration (UF) membranes to enhance the filtration removal of aqueous pharmaceuticals such as ibuprofen and paracetamol. The DES is immobilized over silica nanofiller particles by impregnation, and the composite ChCl-U@SiO2 is embedded at different loadings in the preparation of the PI UF membrane case solutions. The effects of ChCl-U@SiO2 loading on the resulting surface roughness, porosity, average pore size, hydrophilicity, and mechanical properties of the membranes were evaluated and correlated with the UF performance. The modified membrane was assessed using dead-end vacuum filtration experiments to measure the water permeate flux, solution permeate flux, and removal efficiency for 50 ppm paracetamol and 50 ppm ibuprofen from synthetic aqueous mixtures. The results showed that a 2 wt% ChCl-U@SiO2 nanofiller loading was necessary to produce membranes with the optimal aforementioned performance characteristics. The ChCl-U@SiO2 (2 wt%) PI UF membrane showed a significant increase in the water flux (250 L/m2 h) compared to the pristine membrane (30 L/m2 h), due to the enhancement of the hydrophilic character of the membrane. The large water flux was accompanied by an outstanding removal efficiency of up to 99.9% for paracetamol, exceeding that of the bare PI membrane (15%) by ~ 6 folds. The rejection removal of ibuprofen (87%) was roughly 7.9 times greater than that for the pristine membrane. This study provided substantial insights for the potential application of DES as a green modifier in the membrane-based removal of pharmaceutical pollutants from water.

Removal process and mechanism of lead in Zn-containing rotary hearth furnace dust

To deal with the removal of PbO2 during the purification process of the Zn-containing rotary hearth furnace (RHF) dust, this study adopts a choline chloride-urea (ChCl-urea) based deep eutectic solvent system and water-washed Zn-containing RHF dust as the main target of investigations, preparing ZnO nanoparticles using a Zn-induced PbO2 removal and thermal treatment of the precursor. The effects of the mass ratio of Zn particles and Zn dust (maked as Zn particles - Zn dust), reaction temperature, and reaction time on the removal of PbO2 were also investigated. The ZnO nanoparticles and the PbO2-removed products were characterized by X-ray diffractometry, X-ray fluorescence spectroscopy, scanning and transmission electron microscopy. The results showed that the optimal conditions for efficient removal of PbO2 included the reaction temperature of 80 °C, The Zn particles - Zn dust is 1.6, with a reaction time of 3 h. The final product had a ZnO content of 98.332% with a particle size distribution in the range of 10–100 nm with an average diameter of 39 nm, belonging to the Category-II ZnO nanoparticles. The PbO2 removal mechanism mainly involved the dissolving of PbO2 in ChCl-urea, forming [Pb(ClO·urea)2]2−, and the replacement reaction between Zn particles and [Pb(ClO·urea)2]2−, producing metallic Pb and [ZnClO·urea]−.

Effect of Choline-Based Deep Eutectic Solvent Pretreatment on the Structure of Cellulose and Lignin in Bagasse

Deep eutectic solvents (DESs) is a newly developed green solvent with low cost, easy preparation and regeneration. Because of its excellent solubility and swelling effect in lignocellulose, it has received widespread attention and recognition. In this study, choline-based deep eutectic solvents (DESs)—choline chloride-urea (CC-U), choline chloride-ethylene glycol (CC-EG), choline chloride-glycerol (CC-G), choline chloride-lactic acid (CC-LA), and choline chloride-oxalic acid (CC-OA)—were used to extract and separate bagasse. The effects of hydrogen bond donors on lignin separation and the fiber and lignin structure were investigated. All five DESs could dissolve lignin from bagasse; acidic DESs exhibited higher solubility than basic DESs. CC-OA effectively separated lignin and hemicellulose. CC-LA showed weaker lignin separation ability than CC-OA. CC-G, CC-EG, and CC-U were more inclined to selectively separate lignin than hemicellulose. The crystalline cellulose II structure was retained after DES pretreatment. Acidic DESs effectively improved the crystallinity of bagasse fiber; the crystallinities for CC-OA and CC-LA pretreatment were 62.26% and 61.65%, respectively. The lignin dissolved in DES was mainly syringyl lignin. The lignin dissolved in CC-U, CC-LA, and CC-OA contained a small amount of guaiacyl lignin.

Determination of Binding Strengths of Host-Guest Complexes in Deep Eutectic Solvents Using Spin Probe Methodology.

Electron paramagnetic resonance (EPR) and spin probe methodologies have been employed to study the complexation properties of cyclodextrins (CDs) and cucurbit[n]urils (CB[n]s) in the deep eutectic solvent (DES) choline chloride-urea. In the presence of γ-CD an affinity constant very similar to that measured in water was measured in DES with benzyl-tert-butyl nitroxide (BTBN). With β-CD, complexation of BTBN is significantly depressed, although still maintained. Complexation of TEMPO radical probe by CB[7] or CB[8] was instead almost entirely cancelled in DES. In addition, this methodology enabled for the first time to measure the single rate constants for the association and dissociation processes with CDs in DES.