The authors present a one-step method for the assembly of coordination complexes using natural polyphenols and Fe(III) ions, which can coat various substrates, including planar and particle templates. The film formation is initiated by the adsorption of polyphenol and directed by pH-dependent, multivalent coordination bonding. This method is rapid, low-cost, and scalable, with pH-responsiveness and negligible cytotoxicity, making it suitable for biomedical and environmental applications. The FeIII/TA films can be deposited on a wide range of substrates, including glass, gold, polydimethylsiloxane, and biological particles, forming uniform microcapsules with controlled thickness and morphology. The films exhibit pH-dependent disassembly, which is useful for applications where pH varies in different parts of the body. The versatility and potential of this method are demonstrated through its application to various materials and particles, highlighting its potential for advanced material engineering.The authors present a one-step method for the assembly of coordination complexes using natural polyphenols and Fe(III) ions, which can coat various substrates, including planar and particle templates. The film formation is initiated by the adsorption of polyphenol and directed by pH-dependent, multivalent coordination bonding. This method is rapid, low-cost, and scalable, with pH-responsiveness and negligible cytotoxicity, making it suitable for biomedical and environmental applications. The FeIII/TA films can be deposited on a wide range of substrates, including glass, gold, polydimethylsiloxane, and biological particles, forming uniform microcapsules with controlled thickness and morphology. The films exhibit pH-dependent disassembly, which is useful for applications where pH varies in different parts of the body. The versatility and potential of this method are demonstrated through its application to various materials and particles, highlighting its potential for advanced material engineering.