Unlocking the Potential of Gallic Acid-Based Metal Phenolic Networks for Innovative Adsorbent Design

Metal phenolic networks (MPNs) have attracted significant attention due to their environmentally benign nature, broad compatibility, and universal adhesive properties, making them highly effective for modifying adsorbent surfaces. These supramolecular complexes are formed through the coordination of metal ions with natural phenolic ligands, resulting in stable structures while retaining the active adsorption sites of the ligands, thereby enhancing the adsorption performance of unmodified substrates. Among various MPNs, metal ion gallic acid (GA) networks are particularly well-known for their exceptional stability, biological activity, and superior adsorption ability. This review offers a comprehensive examination of GA-based MPN adsorbents, focusing on their formation chemistry, characterization techniques, and applications. The coordination chemistry underlying the stability of GA-metal complexes is analyzed through equilibrium studies, which are critical for understanding the robustness of MPNs. The main analytical methods for assessing metal ligand interactions are discussed, along with additional characterization techniques for evaluating adsorbent properties. This review also explores various synthesis and performance enhancement strategies for GA-based MPN adsorbents, including stand-alone MPNs, MPN-mediated mesoporous materials, MPN-MOF composites, and MPN-coated substrates. By consolidating current advancements in MPN-based adsorbents and offering fundamental insights into their chemistry and characterization, this review serves as a valuable resource for researchers seeking to develop stable, functional metal-organic materials. It aims to drive innovation in sustainable and efficient adsorbent technologies for diverse environmental and industrial applications.