Ion recognition is still an emerging topic in supramolecular chemistry and has aroused great attention in the last few years. In this work, we have examined the assemblies of selected hexameric rosettes of melamine and ammeline and their capacities to host halide and alkali ions in the gas phase and in water. Using relativistic dispersion-corrected density functional theory (DFT-D), we first studied the stability and the effect of introducing monovalent anions (Cl−, Br−, and I−) and cations (Na+, K+, and Rb+) in the center of the rosette’s cavity. Finally, we explored the interactions in two stacked rosettes with an interlayer ion. Our computations reveal that amine-substituted triazines are promising candidates for anion and cation recognition either in self-assembled monolayers or pillar array structures. The anion recognition process is governed by both the electrostatic and charge-transfer (donor−acceptor) interactions, while the cation recognition is governed by electrostatic and polarization. In addition, melamine and ammeline could constitute a potent mixture for dual-ion recognition strategies.