Melamine-based materials and composites for catalytic applications in organic synthesis

The development of efficient, stable, and environmentally benign catalysts advances sustainable organic synthesis. Among emerging materials, melamine, a low-cost, nitrogen-rich heterocycle, has attracted significant attention for its ability to form functional composites with a wide range of advanced materials, including porous organic frameworks (POFs), covalent organic frameworks (COFs), metal-organic frameworks (MOFs), graphene oxide (GO), and graphitic carbon nitride (g-C 3 N 4 ). These materials benefit from melamine's structural versatility, high nitrogen content, and its ability to coordinate with metal centers, making them highly suitable platforms for heterogeneous catalysis. This review provides a comprehensive overview of recent progress in melamine-based composite catalysts, focusing on their structural design, physicochemical properties, and catalytic performance in key organic transformations, such as coupling, condensation, hydrogenation, oxidation, and CO 2 conversion reactions. Particular emphasis is placed on synthetic strategies, structure-activity relationships, and advantages including recyclability, high surface area, and tunable porosity. By mapping the current landscape of melamine-derived catalytic materials and elucidating their mechanistic roles in green chemistry, this review aims to inspire future research and foster innovation at the intersection of materials science and catalysis.