Most of the rod-like liquid crystal compounds (calamitic mesogens), which often exhibit orthogonal smectic phases (SmA, SmB, SmE), have not only a rigid core moiety but also flexible alkyl-chain(s). Although the calamitic mesogens have been investigated for a long time, the roles of the alkyl chain in the orthogonal smectic phases have not been clarified. Here, the importance of alkyl-chain in liquid crystal phases are reviewed. The alkyl-chain is already fully molten even in the SmE phase by the same degree as isotropic liquids, leading to stability of liquid crystal phases. The orientation of the conformationally disordered alkyl-chain yields two types of molecular packing structures in the orthogonal smectic phases. It is demonstrated that the molecular packing structures of the SmA phase correlate closely with the thermodynamic order of the phase transitions between the SmA and nematic phases.

抄録全体を表示

In crystals of chiral molecules, racemic crystals generally have a higher density and are thermodynamically more stable than crystals composed solely of optically active (enantiomeric) molecules (Wallach's rule). We consider that the mixing of enantiomeric pairs (i.e., racemization) drives molecular assembly and have examined its role in the construction of supramolecular structures. Conversely, mixing of opposite enantiomers results in the loss of optical activity. In this paper, we present a method for constructing thermodynamically stable and optically active supramolecular liquid crystals by mixing quasi-enantiomeric molecules in a 1:1 ratio (quasi-racemization). Quasienantiomers are defined as the molecules whose overall shapes are in a mirror-image relationship but some elements are different. Here we use octahedral metal complexes with D and L chirality as quasi-enantiomers and report the formation of thermodynamically stable supramolecular liquid crystals and the observation of unique chiroptical activity.

抄録全体を表示

XRD-DSC is a simultaneous measurement technique that integrates X-ray diffraction (XRD) with differential scanning calorimetry (DSC), allowing real-time observation of both thermal and structural changes under controlled temperature and humidity. This dual approach enables comprehensive analysis of material behavior, serving as a complementary method to the individual techniques. XRD-DSC has been widely used in pharmaceuticals, food engineering, and polymers, offering significant benefits in product development and quality control. This report outlines the principles of XRD-DSC, how to interpret profiles, and recent application examples. In acetaminophen, XRD-DSC captured transitions between metastable polymorphs during heating. For nedocromil sodium, humidity-controlled measurements revealed the transformation from monohydrate to trihydrate at 20 %RH, while TG-DTA confirmed dehydration from trihydrate upon heating. In food applications, butter's structural changes—particularly in lamellar and subcell structures of triacylglycerols—were tracked through thermal cycling, linking thermal history to textural quality. These results highlight XRD-DSC as a powerful and precise tool for evaluating structural and thermal properties simultaneously. Its versatility makes it valuable for optimizing formulation, processing, and storage across diverse industries.

抄録全体を表示

In recent years, the demand for high-temperature thermodynamic data has been increasing due to the widespread use of phase equilibrium calculations based on the CALPHAD method and process simulations in high-temperature industries. Although drop calorimetry using an ice calorimeter is a classical technique, it remains unsurpassed in terms of accuracy and measurement efficiency, and its significance continues to be recognized. In this review, we present the experimental setup of the drop calorimeter, provide measurement examples, and highlight recent developments in the field.

抄録全体を表示