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