Alkyl modification to optimize the ferroelastic properties in molecular crystals

Abstract

Ferroelastics, as an important member of ferroic materials, have significant value in the application of the shape memory, mechanical switches, intelligent sensors, etc. With the development of the technology, ferroelastics with single property have certain limitations in expanding their further applications, and it is still a challenging topic to reasonably find multifunctional ferroelastics, especially those with multi-dielectric response and fluorescence properties. Here, under the guidance of the strategy of alkyl modification, (EMP)PbBr3 (EMP=N-ethyl-N-methyl-3-pyrroline) (compound 2) was obtained successfully by modifying the parent compound (DMP)PbBr3 (DMP=N,N-dimethyl-3-pyrroline) (compound 1). Of note, compound 2 was improved to triple dielectric response compared with double dielectric response of compound 1, and both ferroelastic phase transition temperature and photoluminescence quantum yield of compound 2 were improved. Such changes make compound 2 potentially application in smart electronic devices. This work provides some insights into the search for multifunctional ferroelastics.