H-bond cooperativity: polarisation effects on secondary amides
| Autor: | Soloviev, Daniil O, Hanna, Fergal E, Misuraca, Maria Cristina, Hunter, Christopher A |
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| Přispěvatelé: | Soloviev, Daniil O [0000-0003-4617-9280], Hanna, Fergal E [0000-0002-9376-9921], Hunter, Christopher A [0000-0002-5182-1859], Apollo - University of Cambridge Repository |
| Rok vydání: | 2022 |
| Předmět: | |
| Zdroj: | Chemical Science. 13:11863-11868 |
| ISSN: | 2041-6539 2041-6520 |
| DOI: | 10.1039/d2sc04271a |
| Popis: | Formation of a H-bond with an amide carbonyl oxygen atom increases the strength of subsequent H-bonds formed by the amide NH, due to polarisation of the bond. The magnitude of this effect has been quantified by measuring association constants for the formation of 1 : 1 complexes of 2-hydroxylbenzamides with tri-n-butyl phosphine oxide. In 2-hydroxybenzamides, there is an intramolecular H-bond between the phenol OH group and the carbonyl oxygen atom. Comparison of the association constants measured for compounds with and without the 2-hydroxy group allows direct quantification of the effect of the intramolecular H-bond on the H-bond donor properties of the amide NH group. Substituents were used to modulate the strength of the intramolecular and intermolecular H-bonds. The presence of an intramolecular H-bond increases the strength of the intermolecular H-bond by more than one order of magnitude in n-octane solution. The increase in the H-bond donor parameter used to describe the amide NH group is directly proportional to the H-bond donor parameter of the phenol OH group that makes the intramolecular H-bond. These polarisation effects will lead to substantial cooperativity in complex systems that feature networks of non-covalent interactions, and the measurements described here provide a quantitative basis for understanding such phenomena. |
| Databáze: | OpenAIRE |
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