Two novel phase transition materials based on 1-isopropyl-1,4-diazabicyclo[2.2.2]octan-1-ium

Two novel phase transition materials, [C3H20N2][Na(BF4)(3)] (1) and [C9H20N2][(PF6)(2)] (2), were synthesized based on 1-isopropyl-1,4-diazabicyclo[2.2.2]octan-1-ium with sodium tetrafluoroborate and hexafluorophosphoric acid, respectively. Differential scanning calorimetry measurements detected that 1 and 2 underwent reversible phase transitions, which were confirmed by dielectric measurements. Single crystal X-ray diffraction data suggested that compound 1 changed from a high temperature phase with a space group of P6(3)D to a low temperature one with a space group of P2(1)/c, and that compound 2 transformed from the space group of Pbca at room temperature to P2(1)/c at low temperature. Formation of hydrogen bonds and distortion of 1,4-diazabicyclo[2.2.2]octane rings may drive the transitions. (C) 2016 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.