Different States of water in α-Cyclodextrin hydrates

Different States of water in α-Cyclodextrin hydrates Full article

Journal

The Journal of Chemical Thermodynamics
ISSN: 1096-3626 , E-ISSN: 0021-9614

Output data

Year: 2025, Number: 201, Article number : 107401, Pages count : 9 DOI: 10.1016/j.jct.2024.107401

Tags

α-Cyclodextrin Dehydration Vapor pressure Phase transition Membrane-gauge manometer Thermodynamic characteristics

Authors

Zelenina L.N. ¹ , Chusova T.P. ¹ , Isakov A.V. ¹ , Rodionova T.V. ¹ , Manakov A.Yu. ¹ , Lyrshchikov S.Yu. ²

Affiliations

1	Nikolaev Institute of Inorganic Chemistry Siberian Branch of Russian Academy of Sciences, 3, Acad. Lavrentieva avenue, Novosibirsk 630090, Russia
2	Federal Research Center of Coal and Coal Chemistry SB RAS, Sovetskiy Ave. 18, Kemerovo 650000, Russia

The pressure of saturated and unsaturated water vapor over α-CD⋅nH2O hydrates has been measured by static method with membrane-gauge manometer under conditions of complete loss of water. The temperature dependences of water vapor pressure have been obtained in the wide range of temperatures (287–469 K), pressures (0.04–34.95 kPa) and water content (0.17 ≤ n ≤ 6.0). The data obtained indicate the presence of water molecules with different volatility in α-CD⋅nH2O hydrates. Water molecules with lower volatility can be considered “external”, included in the network of intermolecular hydrogen bonds, while water molecules with higher volatility, discovered in our previous study, are considered “internal”, presumably located in the α-CD cavity. For each composition, the amount of “external” and “internal” water has been determined and the equations described the dependence of the content of each type of water on n in α-CD⋅nH2O have been obtained. The analytical expressions for the lnp – 1/T dependences as well as the values of enthalpy and entropy of processes studied have been calculated. Experimental data were used to obtain the Gibbs energy changes when “external” water molecules bind to the α-CD framework. The values obtained are differed from the values for “internal” water given in our previous study. The phase transition in α-CD⋅nH2O revealed in our previous study is also observed in this work and its thermodynamic characteristics are in good agreement with the results obtained earlier. The findings have been confirmed by 1H NMR studies.

Zelenina L.N. , Chusova T.P. , Isakov A.V. , Rodionova T.V. , Manakov A.Y. , Lyrshchikov S.Y.
Different States of water in α-Cyclodextrin hydrates
The Journal of Chemical Thermodynamics. 2025. N201. 107401 :1-9. DOI: 10.1016/j.jct.2024.107401 WOS Scopus OpenAlex

Submitted:	Apr 27, 2024
Accepted:	Oct 10, 2024
Published online:	Oct 12, 2024
Published print:	Feb 1, 2025

Web of science:	WOS:001335547400001
Scopus:	2-s2.0-85206269346
OpenAlex:	W4403347966

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