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

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.