Solvent Modulation of Aromatic Substituent Effects in Molecular Balances Controlled by CH-π Interactions.
| Autor: | Emenike BU; Department of Chemistry, State of University of New York , Old Westbury, New York 11568, United States., Spinelle RA; Department of Chemistry, State of University of New York , Old Westbury, New York 11568, United States., Rosario A; Department of Chemistry, State of University of New York , Old Westbury, New York 11568, United States., Shinn DW; Department of Math and Science, U.S. Merchant Marine Academy , Kings Point, New York 11024, United States., Yoo B; Department of Chemistry, Hunter College, City University of New York , New York, New York 10065, United States. |
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| Jazyk: | angličtina |
| Zdroj: | The journal of physical chemistry. A [J Phys Chem A] 2018 Feb 01; Vol. 122 (4), pp. 909-915. Date of Electronic Publication: 2018 Jan 23. |
| DOI: | 10.1021/acs.jpca.7b09910 |
| Abstrakt: | CH-π aromatic interactions are ubiquitous in nature and are capable of regulating important chemical and biochemical processes. Solvation and aromatic substituent effects are known to perturb the CH-π aromatic interactions. However, the nature by which the two factors influence one another is relatively unexplored. Here we demonstrate experimentally that there is a quantitative correlation between substituent effects in CH-π interactions and the hydrogen-bond acceptor constants of the solvating molecule. The CH-π interaction energies were measured by the conformational study of a series of aryl-substituted molecular balances in which the conformational preferences depended on the relative strengths of the methyl and aryl CH-π interactions in the folded and unfolded states, respectively. Due to the favorable methyl-aromatic interactions, the balances were found to exist predominantly in the folded state. The observed substituent effect in the conformational preferences of the balances was controlled by the explicit solvation/desolvation of the aryl proton. The interpretation of the conformational free energy as a function of substituents and solvation using Hunter's solvation model revealed that a linear relationship exists between the sensitivity of aromatic substituent effects (i.e., the ρ values derived from Hammett plots) and the hydrogen-bond acceptor propensity (β |
| Databáze: | MEDLINE |
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