Synthesis and Growth of Versatile Systems based on Amino Acid Derivatives: from Supramolecular Organogels to Hierarchical Superstructures and Single Crystals

FEDERICO MOVILLA; JUAN MANUEL REY; CRISTIÁN HUCK IRIART; FLORENCIA DI SALVO

Conferencia; 2nd International Conference on "Crystal Engineering: From Molecule to Crystal [CEFMC-2020]"; 2020

Recent studies show that small molecules based on amino acid derivatives are able to assemble into ordered superstructures, also called mesocrystals1,2, when they are subjected to certain crystallization conditions. The control over experimental parameters as pH, supersaturation level, ionic force and the use of additives, are some of the most popular approaches3 to obtain this new kind of material. Besides, due to its rich supramolecular chemistry, self-assembly strategies applied to some low-molecular weight building blocks can conduct to other kinds of solid materials, such as supramolecular gels4. In this case, their properties can be modulated by changing temperature or solvent, since they are variables that directly affect the nature of the non-covalent interactions within the gel network5,6. Either the development of a spanning network that can immobilize solvents or the self-assembly between building blocks to form a crystal structure, are both governed by the presence of non-covalent interactions. Thus, there is a delicate balance for a low-weight molecule to behave as a gelator or, as a crystal building block. In the present work we analyzed the physiochemical factors implied in the obtaining of different self-assembled structures such as gels and mesocrystals, in a new family of chiral small molecules based on the aryl amino acids L-Tyrosine and L-Phenylalanine. We studied the preferential crystalline orientation within a single polycrystalline aggregate (mesocrystal) obtained under different synthesis conditions. Also, different organogels were studied using diverse spectroscopies techniques in order to gain a clear insight of the solvent-molecule interaction during gelification process. Results are a direct characterization of the hierarchy of the structuration of the material and contribute to elucidate putative mechanisms of the self-assembly based on the synthesis conditions.