Study On Phase Transition Properties Of Phenylethylaminnes Organic-inorganic Hybrid Compounds

When the phase transition of crystal occurs,the structure will change,and the corresponding physical properties(such as thermal properties,dielectric properties and so on)will also change in the vicinity of the phase transition temperature.Therefore,it can be widely used in data storage,photonic devices,optoelectronic technology,switchable dielectric devices,biosensors and so on.Generally,organic-inorganic hybrids are used to construct phase transition materials.The advantage is that these compounds composed of organic ammonium cation and anion(metal halide,inorganic acid)have good structure controllability.Here,based on phenylethylamine compounds with slightly larger molecular volume as organic parts,a series of compounds were synthesized by regulating phenylethylamine cations or anions to search for phase transaction materials.It is mainly divided into three research parts:In the first part,5 compounds were synthesized by the reaction of phenylethylamine,m-chlorophenylamine,p-chlorophenylamine with small molecule organic acids,including[C₈H₈NH₃][CCl₃COO](1),[m-ClC₈H₈NH₃][CCl₃COO](2),[p-ClC₈H₈NH₃][CCl₃COO](3),[C₈H₈NH₃][CHCl₂COO](4)and[m-ClC₈H₈NH₃][CHCl₂COO](5).It is expected to search for phase transition materials by adjusting the position of halogen substituents.In the second part,the screened m-chlorophenethylamine is used as the organic part,and reacted with perchloric acid,tetrafluoroboric acid and hexafluorophosphoric acid to synthesize 3compounds:[m-ClC₈H₈NH₃][ClO₄](6),[m-ClC₈H₈NH₃][BF₄](7)and[m-ClC₈H₈NH₃][PF₆](8),researching phase transition materials by adjusting anions.The third part is mainly based on the meta-halogen substituent phenethylamines,and react with metal halides to synthesize 4 compounds with the molecular formula A₂MX₄ to find high-temperature phase transition multifunctional materials.Including[m-ClC₈H₈NH₃]₂[MnCl₄](9),[m-FC₈H₈NH₃NH₃]₂[MnCl₄](10),[m-ClC₈H₈NH₃]₂[CuCl₄](11)and[p-OCH₃C₈H₈NH₃]₂[CdCl₄](12).Among them,compounds 9 and 10 regulate phase transition properties through organic cations,compounds 9 and 11 regulate phase transition properties through different metal halide anions.Among the 12 newly synthesized compounds,all of them were characterized.And 8compounds have undergone structural phase transition,namely compounds 5,6,7,8,9,10,11,12.Specifically,compound 5 is a low-temperature phase transition,and others are high-temperature phase transitions with stable dielectric switch.Besides,compounds 9 and 10 as two-dimensional layered compounds with formula A₂MnX₄,show good optical properties.Most importantly,compound 10 also exhibits interesting dielectric anisotropy and magnetic anisotropy,and strong antiferromagnetic properties.