Synthesis of Functional Materials Using N-heterocyclic Amines Beyond Melamine.

Melamine, a nitrogen-rich heterocycle with a 1,3,5-triazine core and three exocyclic amines, has played a central role in materials chemistry, enabling the synthesis of supramolecular assemblies, covalent organic polymers, and carbon nitride semiconductors. However, structurally related N-heterocyclic amines, differing in ring substitution or heterocycle, are far less applied in such fields despite their potential to overcome limitations associated with melamine-based materials. In this review, recent advances in the synthesis of covalent and carbon-based materials derived from melamine analogues, including 6-Phenyl-1,3,5-triazine-2,4-diamine, 6-Methyl-1,3,5-triazine-2,4-diamine and 2,4,6-Triaminopyrimidine are highlighted. It is focused on how variations in heterocycle identity and functional group substitution influence monomer reactivity, condensation behavior, and the resulting material properties, such as chemical composition, dimensionality, porosity and morphology. Diverse applications of such materials are discussed, from fluorescent sensing platforms to CO2 capture and photo-electrocatalysis, however, the primary emphasis lies on synthetic strategies and structure-property relationships. It is concluded with a critical perspective on how these alternative building blocks, when leveraging sustainable synthesis methods coupled with emerging AI-guided materials discovery, may enable the targeted design of next-generation functional materials.