Solubility and solvation features of native cyclodextrins in 1-ethyl-3-methylimidazolium acetate

Liquid Structure Scenario of the Archetypal Supramolecular Deep Eutectic Solvent: Heptakis(2,6-di-O-methyl)-β-cyclodextrin/levulinic Acid

“…Therein, it appears that the system is not characterized by long-range spatial correlations, as no indication of lower Q value scattering features appears. We notice that these data look different from related systems, such as the β-CD–reline system or the mixture of β-CD with the [C 2 mim]­[acetate] ionic liquid or even the solution of β-CD in water, where a clear indication of the isolated β-CD geometry (a hollow sphere, after isotropic averaging in space and time) could be detected, fingerprinting the unaggregated nature of β-CD dissolved in those media. The present experimental data set is compared with corresponding quantities extracted from MD simulations conducted on the same system.…”

“…This is the fingerprint of isolated DiMeβ-CDs, analogously to other CD solutions, where isolated CDs are homogeneously distributed, ,, with a distinct feature at ca. 0.5 Å –1 , as reported elsewhere. ,, The mentioned difference between the SAXS pattern reported in Figure and those found in other media ,, is then the consequence of the small electronic density contrast between LevAc and DiMeβ-CDs in the present SUPRA-DES, which hinders the detection of the DiMeβ-CD form factor. Accordingly, the present SAXS pattern only reflects the structure factor associated with the neighbor CD interactions , and the MD simulations clarify that, when properly choosing contrast (in the present case by the selective deuteration of either of the two components), neutron-weighted scattering reveals that the SUPRA-DES morphology corresponds to isolated CDs that are homogeneously distributed in the bulk, without intervening aggregation.…”

“…However, when selectively deuterating only one of the two components (either LevAc (green curve) or DiMeβ-CD (blue line)), a strong low Q signal (below 0.5 Å –1 ) manifests. This is the fingerprint of isolated DiMeβ-CDs, analogously to other CD solutions, where isolated CDs are homogeneously distributed, ,, with a distinct feature at ca. 0.5 Å –1 , as reported elsewhere. ,, The mentioned difference between the SAXS pattern reported in Figure and those found in other media ,, is then the consequence of the small electronic density contrast between LevAc and DiMeβ-CDs in the present SUPRA-DES, which hinders the detection of the DiMeβ-CD form factor.…”

“…However, when selectively deuterating only one of the two components (either LevAc (green curve) or DiMeβ-CD (blue line)), a strong low Q signal (below 0.5 Å −1 ) manifests. This is the fingerprint of isolated DiMeβ-CDs, analogously to other CD solutions, where isolated CDs are homogeneously distributed, 18,63,64 with a distinct feature at ca. 0.5 Å −1 , as reported elsewhere.…”

“…This structural scenario reflects the intricate mingling of HB and dispersive interactions in establishing the homogeneous liquid state of the DiMeβ-CD–LevAc. It is well known that the mere establishment of HB correlations between CDs and solvent cannot guarantee stable CD solutions and the role of dispersive interactions in hindering the hydrophobic coalescence of CD walls has been often highlighted. ,, This study reveals that such a feature is also responsible for the occurrence of highly concentrated CD environments, such as SUPRA-DES. In Table S1, we show a decomposition of interaction energies between CD and LevAc, in terms of Coulombic and dispersive interactions.…”