Crystallization Screening and Theoretical Studies on Molecular Recognition of D-glucose Molecules

Industrial crystallization of glucose is still today one of the most important and widely studied crystal growth processes, such that its world wide annual production reaches the millions of tons. D-glucose takes part in an anomerization equilibrium in solution and crystallizes in three main crystalline forms, namely, α-D-glucose monohydrate, α-D-glucose anhydrous, and β-D-glucose anhydrous. The investigation of molecular recognition is fundamental for the understanding of nucleation process and to try to explain why this kind of molecules with 5 almost free to rotate hydroxyl groups don’t produce a large number of conformational polymorphs. Thus, we performed an extensive and systematic study of crystallization conditions through solvent solvent and solvent gel counter diffusion experiments, looking for new polymorphs, and we outlined a reproducible procedure to obtain high quality single crystals of α-D-glucose, the most studied and common form. In addition, in order to achieve a deep understanding of chemical bonding and intermolecular interactions, we determined electronic properties in solid state through high resolution single crystal XRD at 90 K, determination of charge density using multipolar expansion and DFT quantum mechanical calculations.