Self-Sorting of Two Imine-Based Metal Complexes: Balancing Kinetics and Thermodynamics in Constitutional Dynamic Networks

A major hurdle in the development of complex constitutional dynamic networks (CDNs) is the lack of strategies to simultaneously control the output of two (or more) interconnected dynamic processes over several species, namely reversible covalent imine bonds formation and dynamic metal-ligand coordination. We have studied in detail the factors influencing the fidelity of the self-sorting process (concentration, electronic and steric parameters of the organic components, nature of the metal cations) of 11 constitutional dynamic libraries containing two different amines, aldehydes and metals salts into two imine-based metal complexes, having no overlap in term of their compositions. In all the cases, the outcome of the process was primarily determined by the ability of the octahedral metal ions to select its pair of components from the initial pool of components, the composition of the weaker tetrahedral complex being imposed by the components rejected by the octahedral metal ions. Different octahedral metal ions required different level of precision in the “assembling instructions” provided by the organic components of the CDN to guide it towards a sorted output. The concentration of the reaction mixture, the electronic and steric properties of the initial components of the library were all found to influence the lifetime of unwanted metastable intermediates formed during the assembling of the two complexes.