An Adjustable Cleft Based on an 8-Sulfonamide-2-Naphthoic Acid with Oxyanion Hole Geometry |
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| Authors: | José J. Garrido-González Irene Boya del Teso Dr. Ángel L. Fuentes de Arriba Dr. Francisca Sanz Dr. Eva M. Martín del Valle Dr. Joaquín R. Morán Dr. Victoria Alcázar |
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| Affiliation: | 1. Departamento de Química Orgánica, Universidad de Salamanca, Plaza de los Caídos s/n, Salamanca, 37008 Spain;2. Servicio de Difracción de Rayos X, University of Salamanca, Plaza de los Caídos s/n, Salamanca, 37008 Spain;3. Departamento de Ingeniería Química, Universidad de Salamanca, Plaza de los Caídos s/n, Salamanca, 37008 Spain;4. Departamento de Ingeniería Química Industrial y del Medio Ambiente, Universidad Politécnica de Madrid, C/José Gutiérrez Abascal, 2, Madrid, 28006 Spain |
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| Abstract: | Cleft type receptors showing the oxyanion hole motif have been prepared in a straightforward synthesis starting from the commercial 3,7-dihidroxy-2-naphthoic acid. The double H-bond donor pattern is achieved by the introduction of a sulfonamide group in the C-8 position of naphthalene and a carboxamide at the C-2 position. This cleft, for which the geometry resembles that of an oxyanion hole, is able to adjust to different guests, as shown by the analysis of the X-ray crystal structures of associates with methanol or acetic acid. Combination of hydrogen bonds and charge-transfer interactions led to further stabilization of the complexes, in which the electron-rich aromatic ring of the receptor was close in space to the electron-deficient dinitroaromatic guests. Modelling studies and bidimensional NMR experiments have been carried out to provide additional information. |
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| Keywords: | carboxylic acids charge transfer hydrogen bonds molecular recognition oxyanion hole |
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