The Structures And Dielectric Properties Of Novel Molecular Quaternary Ammonium Derivatives With Halogens Or Aromatic Rings

Recently,phase change materials,due to their rich physical and chemical properties,have attracted much attention from researchers all over the world.Hybrid organic-inorganic materials have been listed to the phase transition research because of their molecular modifiability and functional diversity.So far,many research groups have reported hybrid material systems with structural phase transition.Based on the above,we have designed and synthesized a series of new organic-inorganic hybrid compounds based on new quaternary ammonium salts with diverse halogens or aromatic rings by means of molecular design,and investigated the phase transition characteristics from the aspects of crystal structure analysis and dielectric properties.The main body of the thesis is divided into three parts.The first portion is that four hybrid organic-inorganic compounds(C₄H₁₁NCl)₂Hg₂Cl₆?1?,(C₄H₁₁NI)HgI₃?2?,(C₁₃H₂₂N)?Hg₂Cl₆?_0.5?3?,(C₁₃H₂₂N)₂HgCl₄?4?were synthesized by introducing halogen atoms and aromatic rings into tetramethylamine cations.The second portion is to design and synthesize three hybrid organic-inorganic photoluminescent compounds(C₈H₁₆N)₂MnBr₄?5?,(C₁₀H₁₆N)₂MnBr₄?6?,(C₁₃H₂₂N)₂MnBr₄?7?.The last portion is that four novel organic-inorganic hybrid complexes including(C₁₀H₁₆N)CdCl₃?8?,(C₁₃H₂₂N)₂CdBr₄?9?,(C₁₃H₂₂N)SbCl₄?10?,(C₁₃H₂₂N)₃Bi₂Cl₉?11?were synthesized.Experimental results demonstrate that compound 1,5,8undergo a dielectric anomaly in the vicinity of phase transition point.The differential scanning calorimetry?DSC?and powder diffraction?PXRD?are used to detect these compounds.The symmetry principle is also introduced creatively to analyze the causes of structural phase transition.Other compounds in the cooling and heating process show no reversible dielectric anomalies,which means that these compounds have no structural phase transitions in the measured temperature range.