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.