Nonlinear Optical and Photoluminescence Bistable Responses Accompanied by Tunable Dielectric Behaviors in Crown Inclusions

Abstract

Two host–guest inclusion compounds, [(4-fluorobenzylammonium)­(18-crown-6)]­[ClO4] (1) and [(4-chlorobenzylammonium)­(18-crown-6)]­[ClO4] (2), are found to undergo reversible phase transitions, which enable them to achieve quadratic nonlinear optical (NLO) and photoluminescence bistable switching response characteristics associated with the order–disorder transition of the ClO4 – anions and the coordination environment between the host and guest. By a reasonable selection of suitable organic cations, the regulation of the dielectric relaxation characteristic and dielectric switching property is also realized. To the best of our knowledge, this is the first case of crown ether inclusion to achieve the coexistence of dielectric, NLO, and photoluminescence multiple switching response characteristics, which indicates that our findings provide a new idea for the design of multifunctional switchable materials with crown ether-based host–guest inclusion compounds.

Organometallic-Based Hybrid Perovskite Piezoelectrics with a Narrow Band Gap

“…In addition, the change in the anionic framework has caused a structural distortion which may lead to a change in the molecular dipole moment and increased polarity of the structure. The gradual increase in SHG intensity from (FMTMA)­PbI 3 to (FMTMA)­PbBr 2 I to (FMTMA)­PbCl 2 I may be caused by the variation in dipole moments and polarizations, which are closely related to the SHG characteristics . On the basis of the point charge models of their crystal structures (Figure S5), the spontaneous polarization values of (FMTMA)­PbI 3 , (FMTMA)­PbBr 2 I, and (FMTMA)­PbCl 2 I can be estimated to be 0.005, 0.354, and 0.511 μC cm –2 , respectively, and the corresponding dipole moments in a structural unit cell were estimated to be 0.0103 × 10 –29 , 0.7097 × 10 –29 , and 0.9503 × 10 –29 C m, respectively.…”

A ferroelastic molecular rotator [(Me2N(CH2)2NH3)(18-crown-6)]triflate with dual dielectric switches

“…Tang et al not only reported the dynamics of the ferroelastic phase transition for [(H 3 O)(18-Crown-6)]PF 6 , but also observed its ferroelastic domain patterns. 33 The compound shows a higher ferroelastic-paraelastic phase transition temperature (T c = 287.2 K) compared to other reports, but it is still lower than room temperature. 10,33,37 This means that the reported crown ether-based compounds might not be suitable for commercial application.…”

“…33 The compound shows a higher ferroelastic-paraelastic phase transition temperature (T c = 287.2 K) compared to other reports, but it is still lower than room temperature. 10,33,37 This means that the reported crown ether-based compounds might not be suitable for commercial application. Inspiringly, in the exploration of the molecular ferroelectrics, the ''momentum matching'' strategy implying a proper balance between building blocks has been successfully employed in designing molecular ferroelectrics with excellent performance.…”

“…[25][26][27][28][29][30] This structure is considered as a promising template for the construction ferroelastic phase transition and switchable materials, because it facilitates the dynamic motions of building blocks. 27,[31][32][33][34][35][36] So far, crown ether-based ferroelastic molecular rotators are rarely reported. [(cyclopentylaminium)(18-crown-6)]ClO 4 37 and [(4fluorobenzylammonium)(18crown-6)]ClO 4…”

“…25–30 This structure is considered as a promising template for the construction ferroelastic phase transition and switchable materials, because it facilitates the dynamic motions of building blocks. 27,31–36 So far, crown ether-based ferroelastic molecular rotators are rarely reported. [(cyclopentylaminium)(18-crown-6)]ClO 4 37 and [(4-fluorobenzylammonium)(18crown-6)]ClO 4 33 were reported their structural transition types belong to the ferroelastic species defined by Aizu, but no further evidence for ferroelasticity is available.…”