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Exposing Mechanisms for Defect Clearance in Supramolecular Self-Assembly: Palladium–Pyridine Coordination Revisited

[Image: see text] Spherical three-dimensional (3D) cages composed of palladium(II) and pyridyl ligands are a mainstay of supramolecular chemistry with demonstrated catalytic and optoelectronic applications. The widely reported self-assembly of these palladium-based cages exhibits sensitivity to the...

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Detalles Bibliográficos
Autores principales: Poole, David A., Bobylev, Eduard O., de Bruin, Bas, Mathew, Simon, Reek, Joost N. H.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Chemical Society 2023
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10091417/
https://www.ncbi.nlm.nih.gov/pubmed/36961381
http://dx.doi.org/10.1021/acs.inorgchem.2c04404
Descripción
Sumario:[Image: see text] Spherical three-dimensional (3D) cages composed of palladium(II) and pyridyl ligands are a mainstay of supramolecular chemistry with demonstrated catalytic and optoelectronic applications. The widely reported self-assembly of these palladium-based cages exhibits sensitivity to the solvents, reagents, and/or reactants employed. This sensitivity, and the resulting inconsistency between synthetic protocols, hinders the development of desirable palladium-based cages. We have found that pyridyl ligand substitution—the rate-limiting step of self-assembly—is facilitated by endogenous supporting ligands derived from the solvents, reagents, and reactants employed in synthetic protocols of palladium- and platinum-based assemblies. Here, we present a systematic investigation combining (1)H-NMR, electrospray ionization mass spectrometry (ESI—MS), and absorption spectroscopy to characterize the intermediates to support the mechanism of pyridyl ligand substitution on a model complex, M(py)(2) (M = (N,N,N′,N′-tetramethylethylenediamine)palladium(II), py = pyridine), under simulated synthetic conditions for self-assembly. Our investigation exposes mechanisms for pyridyl ligand substitution, featuring intermediates stabilized by solvent, anion, or (in situ formed) alkoxide moieties. Interrogation of destabilizing agents (2,2,2-trifluoroethanol and tetra(n-butyl)ammonium chloride) reveal similar mechanisms that ultimately facilitate the self-assembly of coordination cages. These findings rationalize widely reported solvent and anion effects in the self-assembly of coordination cages (and similar constructs) while highlighting methodologies to understand the role of supporting ligands in coordination chemistry.