Exploring the dynamics of calix[4]pyrrole: effect of solvent and fluorine substitution
| Autor: | Manuel Marquez, ‡ Jose María López-Bes, Modesto Orozco, Jonathan L. Sessler, F. Javier Luque, J. Ramon Blas |
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| Rok vydání: | 2006 |
| Předmět: |
Models
Molecular Porphyrins Molecular Structure Organic Chemistry chemistry.chemical_element General Chemistry Fluorine Photochemistry Acceptor Catalysis Solvent Crystallography Molecular dynamics chemistry.chemical_compound chemistry Solvents Molecule Solvent effects Calixarenes Conformational isomerism Pyrrole |
| Zdroj: | Chemistry (Weinheim an der Bergstrasse, Germany). 13(4) |
| ISSN: | 0947-6539 |
| Popis: | Molecular dynamics simulations show that calix[4]pyrrole (CP) and octafluorocalix[4]pyrrole (8F-CP) are extremely flexible molecules. CP mainly adopts the 1,3-alternate conformation in all the solvents, although the percentage of alternative conformations increases in polar solvents, especially those with good hydrogen-bonding acceptor properties. However, in the case of 8F-CP, the cone conformation is the most populated in some solvents. Transitions between conformers are common and fast, and both CP and 8F-CP can adopt the cone conformation needed for optimum interaction with anions more easily than would be predicted on the basis of previous gas-phase calculations. Furthermore, the present studies show that when a fluoride anion is specifically placed initially in close proximity to CP and 8F-CP in their respective 1,3-alternate conformations, an extremely fast change to the cone conformation is observed in both cases. The results suggest that preorganization does not represent a major impediment to anion-binding for either CP or 8F-CP, and that ion-induced conformational changes can follow different mechanisms depending on the solvent and the chemical substituents present on the calix[4]pyrrole beta-pyrrolic positions. |
| Databáze: | OpenAIRE |
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