Intramolecular Hydrogen Bond Energy in Polyhydroxy Systems: A Critical Comparison of Molecular Tailoring and Isodesmic Approaches

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• 作者：Milind M. Deshmukh ; Cherumuttathu H. Suresh ; Shridhar R. Gadre
• 刊名：Journal of Physical Chemistry A
• 出版年：2007
• 出版时间：July 19, 2007
• 年：2007
• 卷：111
• 期：28
• 页码：6472 - 6480
• 全文大小：243K
• 年卷期：v.111,no.28(July 19, 2007)
• ISSN：1520-5215

文摘

The intramolecular hydrogen bond (H-bond) energies in several polyhydroxy systems are estimated using anisodesmic/homodesmic reaction approach as well as a molecular tailoring approach (MTA) [Deshmukh, M.M.; Gadre, S. R.; Bartolotti, L. J. J. Phys. Chem. A 2006, 110, 12519]. It is shown that the isodesmic/homodesmic reaction approach as advocated in the literature does not give true H-bond energy but includesthe effect of strain energy due to the formation of a ring structure. Such a ring strain is duly accounted forin the MTA method. The isodesmic H-bond energies are found to be smaller than their MTA energycounterparts typically by the strain energy. The MTA is applied to decitol, a system with more than fivedifferent H-bonds for which an application of an appropriate isodesmic reaction is extremely difficult. It hasbeen shown that the MTA method is able to predict not only the H-bond energies but also the trends inconformational energies for three different conformers of decitol studied in the present work.