Serinol in the Solid State: Structural Diversity and Packing Motifs in Free Base and Salt Forms

Serinol (2-amino-1,3-propanediol) is a key aminodiol used on a multiton industrial scale for the synthesis of iopamidol, a widely employed iodinated contrast agent in computed tomography (CT). Despite its small size and structural simplicity, serinol synthesis and purification remain costly and hazardous. Its isolation from process waste streams typically relies on energy-intensive techniques such as high-vacuum distillation or adsorption-desorption on ion exchange resins, followed by evaporation of large water volumes. Crystallization of serinol offers a more sustainable and potentially scalable alternative. However, systematic crystallographic studies aimed at understanding its solid-state behavior remain scarce. In this work, we report a structural investigation of serinol in its free base form and four of its salts: hemioxalate, hydrochloride, stearate, and adamantane-1-carboxylate. The high density of polar protic functional groups in serinol promotes rich supramolecular architectures, governed by extensive and directional hydrogen-bonding networks. The combined spectroscopic and crystallographic analysis supports the formation of ammonium salts and highlights the structural factors governing their solid-state organization and supramolecular assembly. These insights into the solid-state structure of serinol derivatives lay the groundwork for the rational design of crystallization-based purification of serinol in industrial settings.