From Metal Complexes to BioMOFs: An Experimental Proposal for Teaching Coordination Chemistry Concepts

Abstract

Reactions between metal carbonates from d 5 to d 10 systems and glutamic acid are used to obtain molecular metal complexes and metal−organic frameworks (MOFs). When the ligand is an amino acid, these MOFs belong to the BioMOF class (metal− organic frameworks for biological and medical applications). The metal carbonates of the d 5 , d 6 , and d 8 systems produce molecular complexes with general formulas [M(GluH) 2 (H 2 O) 2 ], whereas those of the d 7 , d 9 , and d 10 systems produce compounds of the type [M(Glu)(H 2 O)• H 2 O] n . Through these syntheses one can explore, among others, concepts largely related to coordination chemistry such as crystal field splitting, weak and strong fields, the chelate effect, coordination number, metal−ligand stability series, Jahn−Teller distortion, acidity and basicity concepts, and crystal structure. In addition, these experiments also provide an opportunity to discuss interaction stability between metal ions with carbonate and hydroxide anions expressed by physical−chemical parameters such as absolute hardness and natural indices for chemical softness, as well as by the respective Pourbaix diagrams.