Halogen substitution creates a promising platform for designing and optimizing materials with a combination of attractive dielectric and semiconductor properties.

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.

A series of multifunctional photoluminescent materials, [pyrrolidinium] 2 MnBr 4 (1), [N-methylpyrrolidinium] 2 MnBr 4 (2), and [N-methylpyrrolidinium]MnBr 3 (3), were obtained by means of regulating diverse organic cations and different coordination modes of inorganic metal ions. Interestingly, compounds 1, 2, and 3 exhibit different dielectric switching and relaxation behavior in the process of structural transformations. Furthermore, compounds 1, 2, and 3 possess intriguing photoluminescence properties. When subjected to UV light, tetrahedrally coordinated compound 1 shows extraordinarily strong [ ‡] These authors contributed equally to this work and should be considered co-first authors.[a]