Different States of water in α-Cyclodextrin hydrates | Sciact - научная деятельность

Different States of water in α-Cyclodextrin hydrates Научная публикация

Журнал

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

Вых. Данные

Год: 2025, Номер: 201, Номер статьи : 107401, Страниц : 9 DOI: 10.1016/j.jct.2024.107401

Ключевые слова

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

Авторы

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

Организации

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

Поступила в редакцию:	27 апр. 2024 г.
Принята к публикации:	10 окт. 2024 г.
Опубликована online:	12 окт. 2024 г.
Опубликована в печати:	1 февр. 2025 г.

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