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Título

Supramolecular chemistry of chiral (1R,2S)-ephedrine confined within the AFI framework as a function of the synthesis conditions

AutorBernardo-Maestro, Beatriz; Roca-Moreno, M. Dolores; López-Arbeloa, Fernando; Pérez Pariente, Joaquín ; Gómez-Hortigüela Sainz, Luis
Palabras claveZeolite
Aggregation
Supramolecular
Self-assembly
Ephedrine
Chirality
Fecha de publicación15-nov-2016
EditorElsevier
CitaciónCatalysis Today 277(part 1): 9-20 (2016)
ResumenIn an attempt to promote chirality in AFI-based materials through spatial distributions of dopants, a systematic variation of the synthesis conditions of Mg-doped aluminophosphate-based microporous materials using chiral (1R,2S)-ephedrine as structure-directing agent has been carried out in order to understand the supramolecular chemistry and packing arrangements of these molecules when confined within the AFI channels. The formation of ephedrine dimers is strongly dependent on the synthesis conditions, especially the ephedrine/H2O ratio (higher concentrations of ephedrine favour the incorporation of dimers), crystallisation temperature (higher temperatures enhance the supramolecular aggregation) and Mg content (lower Mg contents increase the formation of dimers). The latter influence is explained by molecular simulations in terms of an electrostatic repulsion between the ammonium groups of closely-located adjacent dimers when a high density of protonated ephedrine molecules is required in order to compensate for the high Mg incorporation. In this situation, dimers are only incorporated if the system is forced by increasing the concentration of ephedrine in the gel and increasing the temperature. Our results show that a similar number of ephedrine molecules and Mg dopants are incorporated in the AFI unit cell because of charge-balancing purposes, suggesting a strong electrostatic interaction between both species with opposite charge.
Versión del editorhttp://dx.doi.org/10.1016/j.cattod.2015.10.010
URIhttp://hdl.handle.net/10261/162412
DOI10.1016/j.cattod.2015.10.010
ISSN0920-5861
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