Solvophobically Driven Complexation of Adamantyl Mannoside with β‐Cyclodextrin in Water and Structured Organic Solvents

Abstract

The effects of solventa nd temperature on the complexation of adamantyl mannoside with b-cyclodextrin and 6-O-monotosyl-6-deoxy-b-cyclodextrinw ere explored experimentally and by means of molecular dynamics simulations. Efficientb inding was observedo nly in hydrogenbondeds olvents, which indicated solvophobically driven complexation. Thes tability of the inclusion complex was considerably higheri na queous media. Ap ronouncedt emperature dependence of D r H * and D r S * ,r esulting in perfect enthalpy-entropy compensation, was observedi nw ater.The complexation thermodynamicsw as in line with classical rationale for the hydrophobic effect at lower temperatures and the nonclassical explanation at higher temperatures. This finding linked cyclodextrinc omplexation thermodynam-ics with insights regarding the effecto ft emperature on the hydration water structure. The complexation enthalpies and entropies were weakly dependent on temperature in organic media. The signs of D r H * and D r S * were in accordance with the nonclassicalh ydrophobic (solvophobic) effect.T he structures of the optimized product corresponded to those deduceds pectroscopically,a nd the calculated and experimentally obtained values of D r G * were in very good agreement. This investigation clearly demonstrated that solvophobically drivenf ormation of cyclodextrin complexes could be anticipated in structured solvents in general. However,u nlike in water, adamantane and the host cavity behaved solely as structure breakers in the organic media explored so far.[a] SE = standard error of the mean (N = 3o r4). Figure 6. Relative a) conformation and b) solvation contribution to the hydration enthalpies of reactantsand the complex over the studied temperature range.

Molecular Recognition in Water Using Macrocyclic Synthetic Receptors

“…Although the magnitude of Δ C p b should not be used to identify the role of the HE in the binding process, its sizable temperature dependence may be considered a more convincing evidence . With some exceptions, including cyclodextrins and cyclophanes, the effect of the temperature in the thermodynamics of the binding processes of synthetic receptors in water has not been extensively studied …”

“…Although the magnitude of ΔC p b should not be used to identify the role of the HE in the binding process, its sizable temperature dependence may be considered a more convincing evidence. 11 With some exceptions, including cyclodextrins 72 and cyclophanes, the effect of the temperature in the thermodynamics of the binding processes of synthetic receptors in water has not been extensively studied. 49 In water, the temperature dependence of enthalpy is typically reflected in parallel changes of entropy, owing to the almost temperature invariable magnitude of the free energies of binding and protein folding processes in water.…”

Mechano-Responsive Hydrogels Driven by the Dissociation of a Host–Guest Complex

“…Moreover, to clarify the effect of the compression temperature on the mechano-responsiveness, the change in transmittance with respect to the compression temperature was evaluated. It has been reported that the association constant of the host–guest complex of β-CD and Ad in water was almost constant at different temperatures . Therefore, it is expected that the strength of the host–guest interaction itself in the hydrogels did not changed significantly in the range of the temperature from 25 to 50 °C.…”

“…It has been reported that the association constant of the host−guest complex of β-CD and Ad in water was almost constant at different temperatures. 32 Therefore, it is expected that the strength of the host−guest interaction itself in the hydrogels did not changed significantly in the range of the temperature from 25 to 50 °C. Figure 2e shows that above the LCST, the decrease in transmittance, and the signal-to-noise ratio between the pressed and unpressed areas were more significant at higher compression temperatures (37 and 50 °C), whereas at temperatures below or around the LCST (the LCST of P(NIPAAm 95 -co-AdAAm 5 ) was 23 °C in the absence of β-CD), the transmittance was almost the same before and after compression (25 °C).…”

Unravelling binding effects in cyclodextrin inclusion complexes with diamondoid ammonium salt guests

“…Many literature examples exist detailing inclusion complexes of lipophilic adamantane derivatives with b-CDs, [23][24][25][26][27][28][29] but only a few examples describe the binding of larger diamondoid homologues into a bor especially g-CD cavity, which is larger and more flexible. 30 One such recent report deals with adamantane, diamantane and triamantane amines, carboxylic acids and its derivatives as suitable guests for band g-CDs.…”