Super Deuterated Isotope Effect in Phase Transition Materials Based on 2, 6-Dimethylaniline

Abstract

Variable‐temperature single‐crystal X‐ray diffraction and differential scanning calorimetry (DSC) showed that the compounds (C8O5H12N)+⋅ClO4–⋅H2O (1) and (C8O5H12N)+⋅ClO4–⋅D2O (2) underwent reversible phase transitions, as confirmed by dielectric measurements also. The two compounds underwent a phase transition from room‐temperature phase with a space group of Iba2 to lower‐temperature phase with a space group of C2/c. Upon cooling, the crystalline sample of 1 showed a main endothermic peak at 213.8 K, and after using deuterium water instead of water that of 2 exhibited a main endothermic peak at 281.7 K. Compound 2 showed a relatively significantly isotope effect (Tiso= 61–68 K). The dielectric isotope effect was ca. 336.6 % [(44.4–10.1)/10.1], whereas its isotope effect ΔTc was 75 K, being in good agreement with the result of DSC measurement.