Two Low-temperature Phase Transition Compounds Based on Quinuclidine Derivatives with Fluorescence

Two phase transition materials[iPrQ]2MnBr4(1,iPrQ=N-isopropyl-quinuclidinium)and[iPrQ]₂MnCl₄(2)were synthesized and characterized.Dielectric measurements and differential scanning calorimetry showed that the two compounds underwent reversible phase transitions at ca.–47 and–37℃,respectively.Variable-temperature single-crystal X-ray diffraction suggested that the two compounds underwent the same phase transitions from space group C2/c to Cc but at different temperature.The variable crystal structures indicated that the structural phase transitions of the compound were ascribed to the torsional movement of quinuclidine ring and the disappearance of the c-slide plane.The second harmonic generation(SHG)response further proved this structural phase transition.Fluorescence tests showed that the two compounds have strong fluorescence.The strong variations in dielectric anomalies make compounds 1 and 2 suitable for promising switchable dielectric materials.