Structural phase transitions and dielectric transitions in a 1,4-diazabicyclo[2.2.2]octane (dabco) based organic crystal

Organic crystal 1,4-diazabicyclo[2.2.2]octane hydrohexafluorophosphate monohydrate undergoes two reversible phase transitions at 226/268 K and 178/181 K, due to the disorder-order transition of water molecule in the hydrogen bond chain and the twisting of the [Hdabco]+ cation and displacements of the PF6− anion and H2O molecules, respectively.