Vapoluminescence Behavior Triggered by Crystal-State Complexation between Host Crystals and Guest Vapors Exhibiting No Visible Fluorescence

Abstract

A rational design to create vapoluminescence materials is to install fluorescent tags into molecules. Changing the distance and arrangement of the fluorescent tags can be performed to trigger the vapoluminescence behavior. Herein, we unexpectedly observed a vapoluminescence behavior triggered by a crystal-state host–guest complexation between pillar[6]arene host crystals and organic guest vapors that both exhibit no fluorescence in the visible-light region. After the uptake of the guest vapors, the host–guest complex crystals exhibit blue fluorescence in the visible-light region. Charge-transfer interactions between the host and guest molecules in the crystal state mainly contribute to the observation of fluorescence in the visible-light region.