Supramolecular Assembly-Driven Color-Tuning and White-Light Emission Based on Crown-Ether-Functionalized Dihydrophenazine

Abstract

The development of color-tunable white-light-emitting systems is significant for artificial smart materials. Recently, a set of conformational dependent fluorophores <i>N</i>,<i>N</i>'-diaryl-dihydrodibenzo[<i>a</i>,<i>c</i>]phenazines (<b>DPAC</b>s) have been developed with unique photoluminescence mechanism vibration-induced emission (VIE). <b>DPAC</b>s can emit intrinsical blue emission at a bent excited state and abnormal orange-red emission at a planar excited state, which are due to the varied π-conjugation via excited-state configuration transformation along the <i>N</i>-<i>N</i>' axis from bent to planar form. Herein, a novel VIE-active compound <b>DPAC-[B15C5]₂</b> is designed and synthesized with two wings of benzo-15-crown-5. The excited-state vibration of the <b>DPAC</b> moiety can be modulated by tuning the supramolecular assembly and disassembly via chelation competition of K⁺ between 15-crown-5 and 18-crown-6, and hence, a wide-color-tuning emission is achieved from blue to orange-red including white. Dynamic light scattering and transmission electron microscopy experiments were conducted to exhibit the supramolecular assembling process. Additionally, the moisture detection in organic solvents is realized since the water could dissociate the supramolecular assembly.