Functionalities of materials manifest themselves as the result of a concerted effect among molecular structure, intermolecular interactions, and molecular motions. Since the entropy of substance directly reflects the degree of molecular motions, the entropy plays a crucial role when one discusses the stability of a given phase at finite temperatures. When a delicate balance of these three factors is broken, the condensed state faces a catastrophe and is transformed into another phase. Therefore, phase transition is a good probe for elucidation of the interplay between these three factors. As there is no selection rule in thermodynamics, the entropy gain at the phase transition is a good tool to diagnose the mechanism of phase transition. In this presentation, calorimetric investigations aimed at the elucidation of the mechanisms governing phase transitions occurring in molecule-based functional materials are reviewed.
Pure and Applied Chemistry is the official monthly Journal of the International Union of Pure and Applied Chemistry (IUPAC), with responsibility for publishing works arising from those international scientific events and projects that are sponsored and undertaken by the Union.