A novel ferroelectric based on quinuclidine derivatives

The compound[(CH3)2 CH-C3 H17 N][CoBr4](1)based on quinuclidine derivatives was achieved by the solution synthetic method and characterized by elemental analysis,infrared spectroscopy,single-crystal X-ray structural analysis and dielectric measurement,respectively.Variable-temperature single-crystal X-ray diffraction suggested that the compound unde rwent the phase transition from the space group C2/c to Cc.The polarization curve was measured using the Sawyer-Tower circuit.The structural phase transitions of 1 was ascribed to the distortion of a[(CH3)2 CH-C3 H17N]2+cation from this inorganicorganic hybrid material[(CH3)2 CH-C3 H17N][CoBr4].The strong change in dielectric anomalies makes compound 1 a suitable candidate for promising switchable dielectric materials.This work represents a feasible strategy thought for the targeted harvesting of low temperature ferroelectrics.

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]_(2)MnCl_(4)(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.

Quinuclidine and its derivatives as hydrogen-atom-transfer catalysts in photoinduced reactions

Hydrogen-atom-transfer(HAT)is an efficient way for direct C-H functionalization of inert C-H bonds,therefore it has attracted great interests in recent years.So far,various HAT catalysts have been developed.Among them,quinuclidine and its derivatives show different characters toward other HAT catalysts as they tend to abstract electron-rich and hydridic hydrogens in the presence of weak and neutral C-H bonds.These features enable direct C-H functionalization of compounds with various groups which are unable or difficult by other methods.This review summarizes recent advance of photoinduced reactions with quinuclidine and its derivatives as HAT catalysts and exhibits powerful synthetic potential by using quinuclidine and its derivatives as HAT catalysts.