Caffeine (C₈H₁₀N₄O₂) is a purine alkaloid composed of fused imidazole and pyrimidinedione rings. In solution, these relatively planar molecules interact through intermolecular forces—primarily hydrogen bonding (via carbonyl oxygens and ring nitrogens) and π–π stacking between aromatic rings. As the solvent evaporates or cools, the system becomes supersaturated, and nucleation begins: small clusters of caffeine molecules organize into a repeating lattice. From there, crystal growth proceeds via layer-by-layer addition, governed by diffusion rates, temperature, and solvent properties. Slow evaporation typically yields larger, more well-defined crystals, while rapid supersaturation leads to smaller, more irregular structures due to high nucleation density. Under magnification, caffeine crystals can exhibit needle-like or prismatic morphologies depending on growth conditions. These macroscopic shapes reflect the anisotropy of the underlying crystal lattice—growth rates differ along cryst...