Molecular motions in solid 1,6-anhydro-β-D-glucopyranose by 1H nuclear magnetic resonance

Abstract

When crystalline 1,6-anhydro-β-D-glucopyranose is heated, the low-temperature form (phase II) is transformed to a ‘plastic crystal’(phase I). ¹H Nuclear magnetic resonance studies have shown that phase II possesses an effectively rigid lattice. After a transition to phase I which takes place at ca. 385 K the molecules begin to reorient about their centres of gravity and, as the temperature is raised further, measurable molecular self-diffusion occurs with an activation energy of 18 ± 2 kcal/mol.