Thermodynamics of Anion鈭捪€ Interactions in Aqueous Solution

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• 作者：Paloma Arranz-Mascar贸s ; Carla Bazzicalupi ; Antonio Bianchi ; Claudia Giorgi ; Maria-Luz Godino-Salido ; Maria-Dolores Guti茅rrez-Valero ; Rafael Lopez-Garz贸n ; Matteo Savastano
• 刊名：The Journal of the American Chemical Society
• 出版年：2013
• 出版时间：January 9, 2013
• 年：2013
• 卷：135
• 期：1
• 页码：102-105
• 全文大小：263K
• 年卷期：v.135,no.1(January 9, 2013)
• ISSN：1520-5126

文摘

Thermodynamic parameters (螖G掳, 螖H掳, T螖S掳), obtained by means of potentiometric and isothermal titration calorimetry (ITC) methods, for the binding equilibria involving anions of high negative charge, like SO₄^{2鈥?/sup>, SeO₄2鈥?/sup>, S₂O₃2鈥?/sup> and Co(CN)₆3鈥?/sup>, and nitroso-amino-pyrimidine receptors in water suggested that anion鈭捪€ interactions furnish a stabilization of about 鈭?0 kJ/mol to the free energy of association. These anion鈭捪€ interactions are almost athermic and favored by large entropic contributions which are likely due to the reduced hydrophobic pyrimidine surface exposed to water after anion aggregation, and the consequent reduced disruptive effect on the dynamic water structure. The crystal structure of the {H₄L[Co(CN)₆]}路2H₂O complex showed strong anion鈭捪€ interactions between Co(CN)₆3鈥?/sup> and the protonated H₄L3+ receptor. The CN路路路centroid distance (2.786(3) 脜), occurring with a cyanide N atom located almost above the centroid of the pyrimidine ring, is the shortest distance till now reported for the interaction between CN鈥?/sup> ions and heteroaromatic rings.}