DI SALVO Florencia
congresos y reuniones científicas
Self-assembly of new chiral l-aspartic acid derivatives into hierarchical nanoporous microspheres
OLGA C. SÁNCHEZ MONTILVA; FEDERICO MOVILLA; FLORENCIA DI SALVO
Congreso; Reunión Anual Asociación Argentina de Cristalografía; 2015
Amino acids and derivatives are able to self-assemble into ordered superstructures when they are subjected to certain crystallization conditions such as, pH, supersaturation level and the use of additives. While different morphologies of crystalline arrangements are known, the greatest interest lies in the obtaining of three-dimensional (3D) self-assemblies with hierarchical architectures that can contribute to the knowledge of the controlled manufacture of novel devices. However, only a few organic molecules have been considered as building blocks [1 - 3]. In this work we present the synthesis of new chiral L-aspartic acid based molecules which after protonation using several organic acids, give place to different types of hierarchical microspheres. All of them were characterized by polarized optical microscopy (POM), scanning electron microscopy (SEM), XRD, FTIR and NMR, confirming that the resultant material is built exclusively by the organic compound. We suggest that the formation of such organized structures is promoted mainly by the presence and directionality of the hydrogen bonds sustained by the carboxylate groups. Other aspect to point out is that, in all studied cases the compounds are obtained as a mixture of the two possible geometric isomers with symmetry C3h and Cs, respectively. Surprisingly, only the latter give place to mentioned microspheres. On the other hand, the analysis of the images obtained by SEM showed nanopores distributed homogeneously in the symmetrical microspheres, making them a potential material for gas sorption applications. Jiang, H. et al., Cryst. Growth Des, 11, 3243?3249 (2011).  Wohlra, S. et al., Angew. Chem. Int. Ed, 44, 4087 ?4092 (2005).  Ejgenberg, M.,Cryst. Growth Des, 12, 4995−5001 (2012).