| In recent years,molecular ferroelectric materials have attracted more and more attention because of their excellent structural properties.Its distinctive features are easy to form thin films,structural tunability and high mechanical flexibility.Molecular ferroelectric materials are desirable for next-generation flexible and devices wearable electronic.In addition,we have observed that homochirality is only widely used in the pharmaceutical industry,and very few are used in molecular ferroelectric materials.Based on this,the homochiral compound which is the basic unit formed by the widespread living organisms in nature.The homochiral molecules to design enantiomorphic crystals greatly increase the possibility of falling into ferroelectric space group.Based on the advantages of both,the introduction of homochirality in ferroelectric materials can increase their biocompatibility and environmental stability.Specifically,the research of ferroelectric materials could even have rosy prospects in optical,electrical,piezoelectric and other aspects.In order to design and explore new homochiral molecular ferroelectric materials,we usually introduce the chiral center on the modified cations to make the generation of ferroelectricity possible.Herein,9 novel crystalline compounds were presented through the self-assembly method of Racemic compound 3-Chloro-2-hydroxypropyltrimethylammonium(Rac-CTA),homochiral molecular R-3-Chloro-2-hydroxypropyltrimethylammonium(R-CTA)and homochiral molecular S-3-Chloro-2-hydroxypropyltrimethylammonium(S-CTA)and metal halides containing the elements of Cu,Cd and Co:[Rac-CTA]2[Cu Cl4](compound 1),[R-CTA]2[Cu Cl4](compound 2),[S-CTA]2[Cu Cl4](compound 3),[Rac-CTA]2[Cd Cl4](compound 4),[R-CTA]2[Cd Cl4](compound 5),[S-CTA]2[Cd Cl4](compound 6),[Rac-CTA]2[Co Cl4](compound 7),[R-CTA]2[Co Cl4](compound 8),[S-CTA]2[Co Cl4](compound 9).The synthesis process,TGA spectrum,IR spectrum,VCD spectrum,crystal structure,PXRD spectrum,SHG spectrum,dielectric properties,domain structure and PFM of these 9crystalline compounds were presented to investigate their unique structures and properties.Strikingly,compound 1 has no ferroelastic properties,but there are ferroelastic phase transitions in the compounds 2 and 3,which has the property of thermochromic,and also has seven physical channel switches.Similarly,compound 4 has no ferroelectric properties,but in compounds 5 and 6,the excellent properties of compound 4 are inherited,and they have ferroelectric phase transitions.Otherwise,Compounds 8 and 9 crystallized in the ferroelectric point group at the low temperature phase.In summary,the introduction of chiral center on the modified cations is conducive to generation the ferroelectric phase adopting the chiral polar space group,which is expected to provide an effective idea in the development of molecular ferroelectric materials. |
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