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Effect of Solvent Choice on the Self‐Assembly Properties of a Diphenylalanine Amphiphile Stabilized by an Ion Pair
Author(s) -
Mayans Enric,
Ballano Gema,
Sendros Javier,
FontBardia Merçè,
Campos J. Lourdes,
Puiggalí Jordi,
Cativiela Carlos,
Alemán Carlos
Publication year - 2017
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201700180
Subject(s) - solvent , chemistry , aqueous solution , amphiphile , amide , peptide , ionic liquid , ionic bonding , carboxylate , self assembly , molecule , polymer chemistry , solvent effects , ionic strength , organic chemistry , ion , copolymer , polymer , catalysis , biochemistry
A diphenylalanine (FF) amphiphile blocked at the C terminus with a benzyl ester (OBzl) and stabilized at the N terminus with a trifluoroacetate (TFA) anion was synthetized and characterized. Aggregation of peptide molecules was studied by considering a peptide solution in an organic solvent and adding pure water, a KCl solution, or another organic solvent as co‐solvent. The choice of the organic solvent and co‐solvent and the solvent/co‐solvent ratio allowed the mixture to be tuned by modulating the polarity, the ionic strength, and the peptide concentration. Differences in the properties of the media used to dissolve the peptides resulted in the formation of different self‐assembled microstructures (e.g. fibers, branched‐like structures, plates, and spherulites). Furthermore, crystals of TFA ⋅ FF‐OBzl were obtained from the aqueous peptide solutions for X‐ray diffraction analysis. The results revealed a hydrophilic core constituted by carboxylate (from TFA), ester, and amide groups, and the core was found to be surrounded by a hydrophobic crown with ten aromatic rings. This segregated organization explains the assemblies observed in the different solvent mixtures as a function of the environmental polarity, ionic strength, and peptide concentration.