Above Room Temperature Organic Dielectric Switchable Material: Diprotonated 1,4-Diazabicyclo[2.2.2]octane Shifts between Two Pyruvic Acids: Above Room Temperature Organic Dielectric Switchable Material: Diprotonated 1,4-Diazabicyclo[2.2.2]octane Shifts between Two Pyruvic Acids

A pure organic single crystal, [H(2)dabco]center dot[PA](2) ([H(2)dabco](2+) = diprotonated 1,4-diazabicyclo-[2.2.2]octane, PA = pyruvic acid), was synthesized and its dielectric property was studied. [H(2)dabco]center dot[PA](2) owns a distinctive architecture composed of discrete hydrogen-bonded trimeric units, of which one [H(2)dabco](2+) cation bridged by two PA(-) anions through N-H center dot center dot center dot O hydrogen bonding. The switchable property around 348 K was revealed by crystal structure studies between low and high dielectric states. In the high temperature phase, the [H(2)dabco](2+) cation presents itself in a rotationally disordered state and lies at the symmetric center of the trimer. In the room temperature phase, it is frozen in an ordered state and shifts toward a PA(-) anion at one end along the hydrogen bond.