| Organic-inorganic hybrid metal halide,as a new type of multifunction material,exhibiting multitudinous physical/chemical properties through the external stimulation such as pressure,thermal,electric and magnetic field which aroused intense concern owing to their potential applications in switchable dielectric devices,temperature sensors,and data storage,etc.In this paper,1,4,5,6-tetrahydropyrimidine and 4,5-dihydro-1H-imidazole derivative onioumions formed by the in-situ reaction of organic diamine and formic acid were used as organic cation templates to induce seven new types of organic-inorganic hybrid metal halide.And three examples of diammonium directly used as templates were obtained.The physical properties such as reverible phase transition,dielectric,nonlinear optics,and thermochromism of some complexs were explored.1.Four new organic-inorganic hybrid materials[THPM]n[Ag I2]n(1),[DDHID]n[Pb I3]n(2),[AOTHMP]2n[Pb3I10]n(3)and[AOTHPM]n[Pb Br4]n(4)were prepared by reacting 1,3-propanediamine,N,N'-diethylethylene diamine and3,3'-diaminopropanediamine with formic acid,metal nitrate and halogen acid in solvothermal conitions.Structural analysis shows that the inorganic parts of complexs1,2,and 3 are all one-dimensional chain structures,while 4 has a two-dimensional Pb Br4 layer with organic cations filled in the voids of the layers.DSC and dielectric studies show that 1 and 2 have obvious reversible phase transitions at 82?and 162?.Futher 2 reaches the melting point at 215?and the solidified sample can still maintain the original structure.It is interesting that the crystalline samples of 2 can obtain at a wide range of synthesis temperatures,but with different color,which changes from dark grey to bright yellow.As synthesis temperature changing from80?-140?.EPR results show that the dark sample has a strong paramagnetic signal,which indicates the thermochromic behavior of 2 is attributed to the electron transfer(ET)of the organic cation and inorganic part,and the higher temperature obviously inhibits this change.The variable temperature structure studies show that the 2crystallizes in the non-centrosymmetric P63cm space group at the low temperature phase,and centrosymmetric space group P63/mcm at the high temperature phase.Further 2 has obvious second-order nonlinear optical and ferroelectric properties.3and 4 induce two different dimensional organic-inorganic hybrid metal halides due to the use of different halogens.2.Three zero-dimensional examples[DTHPM]6n[Bi2I9]2n(5),[THPM]n[Bi I6]n(6),[DTHPM]3n[Bi I6]n(7)were construced by reacting HI,formic acid lead bismuth nitrate and 1,3-propanediamine or N,N'-dimethyl-1,3-propanediamine.5 has a(Bi2I9)3-dimer structure,while 6,7 have mononuclear(Bi I6)3-structure.DSC and dielectric results indicated complex 5 has a significantl phase transition at about175?,and reaches the melting point at 180?.Obvious reversible thermochromism was observed in 5 and 6,in which the color of crystals changes gradually from light yellow to dark red.3.Three complexs[H2ETDM]n[H2ETDM]0.5n[Bi I6]n·[H2O]n(8);[H2DTPM]n[Pb I4]n(9);[H2ETDM]n[Pb I4]n(10)were obtained using N,N'-diethylethylenediamine(ETDM)and N,N'-dimethyl-1,3-propanediamine(DTPM)as templates in solvothermal conditions.8 has a(Bi I6)3-mononuclear structure.9,10 have similar one-dimensional Pb I4 chain structure,the protonated organic amine cations are filled between the inorganic components. |
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