Structural Diversity and Properties of Coordination Complexes Based on Chiral Amino Acid-Derived Ligands

FLORENCIA DI SALVO; FEDERICO MOVILLA; MARQUINA, ANDREA RIVAS; JUAN MANUEL REY; OLGA C. SÁNCHEZ MONTILVA

Cartagena de las Indias

Simposio; 7th Latin American Symposium on Coordination and Organometallic Chemistry; 2019

Amino acids are among the most readily available sources of enantiomerically pure chiral compounds. Due to presence of N- and O-donor functional groups, amino acids are excellent ligands for transition-metal acceptors. Alternatively, the possibility of derivatization establishes amino acids an even more powerful moiety to explore the synthesis of chiral transition-metal complexes. Among others, one of the most popular applications of chiral transition-metal complexes is their use as catalysts for the obtaining of pure enantiomers of organic products. On the other hand, the mentioned functional groups together with others provided by the amino acid bone, are able to establish strong intermolecular interactions such as H-bonds, and thus make them and their derivatives suitable building blocks for the construction of very stable crystalline solid materials.1In our group we explore the synthesis of chiral molecules through the reaction of amino acids with a wide variety of aldehydes and the subsequent reduction.2 As mentioned, they are also able to act as ligands in the synthesis of coordination compounds. What is more, the relative position of both functionalities makes them suitable as quelates. In this presentation we will show the results achieved for a family of derivatives obtained using the aldehyde piperonal and the amino acids L-Ala, L-Phe and L-Tyr. Depending on the synthesis conditions, ligand identity and the metal ion, it was possible to obtain coordination compounds showing different molecularity and properties. All of them were characterized by different spectroscopies and their molecular and supramolecular structures were studied based on single crystal X-ray diffraction experiments. Besides, some of them where tested as catalysts for the synthesis of enantiopure molecules.A clear demonstration of the amino acid influence is observed for the L-Ala derivatives, since only mononuclear compounds where obtained so far. On the contrary, for the ligands bearing the L-Phe or L-Tyr amino acids, different coordination systems where observed. Other example is the trinuclear Ni(II)-carbonate complex constructed by the self-assembly of L-Tyr based ligands incorporating ambient CO2 as a central μ3-CO32? bridging unit shown in Fig. 1. Surprisingly, when the L-Tyr ligand is replaced by its L-Phe analogue, the resulting crystalline material corresponds to a mononuclear Ni(II) complex which does not show the property of the CO2 uptakeReferences1H. Amouri, M. Gruselle, Chirality in Transition Metal Chemistry: Molecules, Supramolecular Assemblies and Materials, John Wiley & Sons, UK, 2008.2F. Di Salvo, F. Movilla, J. M. Rey, O. C. Sánchez Montilva, Acta Cryst. 2017, A73, C1097.