The Complexation of Aliphatic Guests with Cucurbiturils and Cyclodextrins

Požar, Josip; Usenik, Andrea; Šekutor, Marina; Alešković, Marija; Leko, Katarina; Pičuljan, Katarina; Roca, Sunčica (2024) The Complexation of Aliphatic Guests with Cucurbiturils and Cyclodextrins. In: Kassal, Petar; Meštrović, Ernest; Namjesnik, Danijel; Šekutor, Marina; Tomišić, Vladislav; Usenik, Andrea, (eds.) Solutions in Chemistry 2024: Book of Abstracts. Zagreb, Hrvatsko kemijsko društvo, p. 96 .

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Abstract

The supramolecular recognition of non-polar guests by macrocyclic ligands has received much attention over the past decades.1,2 Contrary to the endothermic micellization (classical hydrophobic effect), the complexation is, due to the removal of energetic solvent from the receptor cavities, predominantly exothermic, even completely enthalpy driven (non-classical hydrophobic effect).1,2 Considering a particularly strong temperature dependence of hydration enthalpies for aliphatic compounds, one would expect a notable influence on the corresponding inclusion thermodynamics. Still, the complexation reactions were primarily investigated at 25 °C. With this in mind, we examined the binding of linear and (poly)cyclic aliphatic guests with size compatible cyclodextrins and cucurbiturils by means of ITC and NMR over a 278−338 K temperature range. A pronounced ΔrH°(T) and ΔrS°(T) dependence due to temperature-induced disordering of the guest‑hydrating water was observed for examined reactions.3,4 This significantly affected the thermodynamics of cyclodextrin complexation reactions, however the inclusion within cucurbiturils remained predominantly enthalpy driven at all examined temperatures.3,4 The carried out investigations also revealed that the dehydration of cucurbituril cavities is accompanied with lower entropy changes than the analogous process involving cyclodextrins.3,4 Apart from that, the endothermic binding of larger diamondoid guests with γ‑cyclodextrin at lower temperatures supports the classical hydration of these bulky guests

Item Type:	Conference or workshop item published in conference proceedings (UNSPECIFIED)
Uncontrolled Keywords:	diamondoid ammonium salts; cyclodextrins; host-guest chemistry; thermodynamics
Subjects:	NATURAL SCIENCES NATURAL SCIENCES > Chemistry NATURAL SCIENCES > Chemistry > Organic Chemistry
Divisions:	Division of Organic Chemistry and Biochemistry
Depositing User:	Kristina Ciglar
Date Deposited:	17 Sep 2025 14:03
URI:	http://fulir.irb.hr/id/eprint/9986

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