Quantitative Measurement of Cooperativity in H-Bonded Networks
| Autor: | Trevisan, Lucia, Bond, Andrew D, Hunter, Christopher A |
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| Přispěvatelé: | Trevisan, Lucia [0000-0002-9745-1275], Bond, Andrew D [0000-0002-1744-0489], Hunter, Christopher A [0000-0002-5182-1859], Apollo - University of Cambridge Repository |
| Rok vydání: | 2022 |
| Předmět: | |
| DOI: | 10.17863/cam.88915 |
| Popis: | Funder: AstraZeneca Cooperative H-bonding interactions are a feature of supramolecular networks involving alcohols. A family of phenol oligomers, in which the hydroxyl groups form intramolecular H-bonds, was used to investigate this phenomenon. Chains of intramolecular H-bonds were characterized using nuclear magnetic resonance (NMR) spectroscopy in solution and X-ray crystallography in the solid state. The phenol oligomers were used to make quantitative measurements of the effects of the intramolecular interactions on the strengths of intermolecular H-bonding interactions between the H-bond donor on the end of the chain and a series of H-bond acceptors. Intramolecular H-bonding interactions in the chain increase the strength of a single intermolecular H-bond between the terminal phenol and quinuclidine by up to 14 kJ mol-1 in the n-octane solution. Although the magnitude of the effect increases with the length of the H-bonded chain, the first intramolecular H-bond has a much larger effect than subsequent interactions. H-bond cooperativity is dominated by pairwise interactions between nearest neighbors, and longer range effects are negligible. The results were used to develop a simple model for cooperativity in H-bond networks using an empirical parameter κ to quantify the sensitivity of the H-bond properties of a functional group to polarization. The value of κ measured in these systems was 0.33, which means that formation of the first H-bond increases the polarity of the next H-bond donor in the chain by 33%. The cumulative cooperative effect in longer H-bonded chains reaches an asymptotic value, which corresponds to a maximum increase in the polarity of the terminal H-bond donor of 50%. |
| Databáze: | OpenAIRE |
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