Synthesis,Structure And Properties Of Tetramethylammonium And Quinuclidine Cationic Hybrid Metal Halides

When plastic crystals can realize ferroelectricity,they will become very promising ferroelectrics.Due to the low rotational energy barrier of spheroid molecules,seven multifunctional organic-inorganic hybrid and single-component materials with ferroelectric,dielectric,semiconductive and luminescent properties were designed and synthesized using tetramethylammonium[Me₄N]⁺and quinine ring organic cations as prototypes,and the structure and related properties of the compounds were studied.The main contents are as follows:1.Based on tetramethylammonium[Me₄N]⁺cation,four new zero-dimensional organic-inorganic hybrid metal halide plastic ferroelectrics were designed and synthesized:trimethyl allyl group ammonium ferric chloride[（CH₃）₃NCH₂CH₂CH₂]FeCl₄（1）,triethyl chloromethyl ammonium bromide cadmium[（CH₂CH₃）₃NCH₂Cl]₂CdBr₄（2）and R/S-（2-hydroxypropyl）-triethylammonium tin chloride R/S-[CH₃CH（OH）CH₂N（CH₂CH₃）₃]₂SnCl₆（3/4）,with phase transition temperatures of 393 K,421 K and 359 K respectively,which have good dielectric switching and semiconductor properties.Compound 1 has obvious ferroelectric domains with spontaneous polarizability of 0.18μC/cm².Compound 2 is a multifunctional plastic phase transition material with photoluminescence characteristics.Compounds 3 and 4 are multifunctional enantiomeric plastic phase transition materials with chiral characteristics.New molecular plastic ferroelectrics provide new opportunities for the development of modern energy and artificial intelligence.2.An organic-inorganic hybrid perovskite photoelectric multifunctional material,N-fluoromethylquinone lead bromide[C₇H₁₃ONCH₂F]PbBr₃（5）,was synthesized by reasonably designing the organic cation[C₇H₁₃ONCH₂F]⁺,introducing the"quasi-spherical theory"of fluorine atoms,and properly introducing inorganic anions.The material crystallizes in P2₁/c space at room temperature,and has T_c=374 K/346 K high temperature reversible phase transition point and ultra-low loss high-quality dielectric switching response.The order-disorder transition of organic cations and the change of the distortion degree of inorganic skeleton induce the structural phase transition.In addition,compound 5 has excellent semiconductor characteristics of 3.06 e V band gap and photoluminescence characteristics of STE broadband emission.This simultaneous multi-organic cation modification strategy provides a new choice for enriching and coupling a variety of high-quality organic-inorganic hybrid perovskite reversible phase transition photoelectric materials.3.According to the quasi-spherical theory,a pair of single chiral reversible plastic phase transition materials（R and S）,10,2-camphor sulfonate（6-R and 7-S）,with a reversible phase transition point of 390 K,was found.Compounds 6 and 7 crystallized in P2₁2₁2₁ space group at room temperature,and the structural phase transition was confirmed by variable temperature PXRD method.Compounds 6 and 7 have good low-loss dielectric switching properties.Through Hirshfeld surface analysis and calculation,the intermolecular interaction force,band gap and absorption wave of compounds 6 and7 were calculated.This work provides a new method for the study of organic single-component reversible plastic phase transition materials.