Competitive Binding-Modulated Metal–Phenolic Assemblies for Adaptable Nanofilm Engineering

Coordination-driven metal–phenolic assembly, a mechanism associated with many essential biological functions, is being actively exploited for engineering of advanced materials. However, a critical challenge remains in the regulation of the dynamic metal–phenolic networks to overcome the kinetic trapping for well-controlled nanofilm formation. This study presents an adaptable competitive binding strategy to shape the metal–phenolic complexes while modulating their assembly behaviors. Kinetically stable metal–phenolic assemblies with homogeneous hydrodynamic diameters are identified as a new class of metal–phenolic building blocks. Spectroscopic studies and density functional theory calculations reveal an inner-sphere complexation of the competitive ligands to the metal centers of bis-complex metal–phenolic species. Quantitative insights into the availability of competitive ligands are achieved, and a series of applicable ligands are located. Particularly, these kinetically stable building blocks, with good dispersibility in both aqueous and organic media, revolutionize the processing of metal–phenolic nanofilms, enabling the use of versatile industrially friendly methods including homogeneous spray coating, vertical deposition self-assembly, and ink-jet printing. The obtained films exhibit superior properties in terms of mechanical strength (E_Y = 13.7 GPa), surface smoothness, and reinforced adhesion force. This study provides new mechanistic understanding of the coordinative metal–phenolic assembly and activates the toolkit of supramolecular chemistry for controllable engineering of metal–organic hybrid films for multidisciplinary applications.