Advances in hybrid organic–inorganic coordination complexes (HOICCs) as a new generation of smart anti-corrosive materials

Hybrid organic–inorganic coordination complexes (HOICCs) are an emerging class of materials that combine the structural robustness of inorganic components with the tunable functionality of organic ligands. This unique synergy imparts HOICCs with high coordination bond strength, structural diversity, and adaptability, distinguishing them from conventional corrosion inhibitors. These advantages translate into superior anticorrosive performance, including the ability to form stable protective films, modulate electrochemical environments, and provide dynamic, stimulus-responsive protection in aggressive conditions. This review systematically explores the role of HOICCs in corrosion protection. First, the fundamental structural classifications of HOICCs—framework-based, discrete, and polymeric complexes—and their influence on bond strength, architecture, and functional tunability have been outlined. Next, recent progress in synthetic approaches is summarized, including solution-based, electrolytic processing (EP), layer-by-layer (LbL), and gas-phase methods (Chemical vapor deposition (CVD), atomic layer deposition (ALD), molecular layer deposition (MLD)), which enable precise control over composition and structure. The review then discusses the mechanisms by which HOICCs inhibit corrosion, supported by electrochemical evaluation methods such as electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP). Finally, key challenges—including scalability, long-term stability, and environmental risks—are analyzed alongside forward-looking opportunities for integrating HOICCs with machine learning, green chemistry, and multifunctional coating design. The purpose of this review is to consolidate current knowledge of HOICCs as corrosion inhibitors, highlight their advantages over conventional strategies, and provide insights into future directions for their development as sustainable, high-performance solutions in industrial corrosion protection.