Hydrogen-bonded 2-benzylphenol and its crystalline polymorphism

The thermal and infrared (IR) spectroscopic measurements of 2-benzylphenol were performed during the crystallization process of the stable and metastable phases. The analysis of the IR spectra of metastable phases in the OH stretching vibration region allows us to conclude that, in contrast to the structure of the stable polymorph, which consists of cyclic tetramers of hydrogen-bonded molecules, the structure of metastable polymorphs consists of chains of hydrogen-bonded molecules. The differential scanning calorimetry experiments have shown that in purified samples only one metastable polymorph was formed with melting temperature 290.2 K. In the samples which were used without purification two metastable polymorphs were observed, with melting temperatures 290.2 and 296.6 K. Both polymorphs melt well below the stable one, which melts at 324.7 K. At temperature similar to 1.1 T-g, generation of the fluctuating crystal nuclei of the metastable phase in supercooled liquid begins.