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

Variable-temperature single-crystal X-ray diffraction and differential scanning calorimetry (DSC) showed that the compounds (C8O5H12N)(+)center dot ClO4-center dot H2O (1) and (C8O5H12N)(+)center dot ClO4-center dot 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 (T-iso= 61-68 K). The dielectric isotope effect was ca. 336.6% [(44.4-10.1)/10.1], whereas its isotope effect Delta T-c was 75 K, being in good agreement with the result of DSC measurement.