Unraveling the genesis of large supramolecular structures obtained from single aryl amino acid-based molecules

Full text: Molecular self-assembly refers to the spontaneous assembly of precursor molecules to form structures though noncovalent interactions. In order to control the architecture of the resulting system, it is necessary to design building blocks assuring the presence of the functional groups which conduct to the development of stable intermolecular interactions with the desired directionality. A large self-assembled supramolecular structure can be obtained using small amino acid-based molecules as building blocks by changing the physicochemical variables of the environment, namely ionic strength, the nature of the solvent, thermal history, an others. These well-organized supramolecular assemblies are employed for several technological applications and they are related to several degenerative disorders, including Alzheimer's disease, Parkinson's diseases, and type II diabetes. In this work, a lamellar-like self-assembly model in organic media has been proposed based on single aryl amino acid, L-Phe or L-Tyr, derivatized with the aldehyde piperonal. The main core of the assembly was constructed by ionic intermolecular interactions assisted by H-bonds and, also, with the contribution of contacts involving the aromatic systems. This model was built using X-ray diffraction, density functional theory, small angle X-ray scattering and nuclear magnetic resonance results. The physicochemical entails described at molecular and nanometric level establish the seeds for the formation of crystalline and non-crystalline mesostructures which are triggered by the synthesis conditions. (author)