Water friendly room temperature phosphorescence doped materials prepared via metal organic framework matrix transformation

Abstract

Stimuli-responsive room temperature phosphorescence (RTP) materials have wide applications. However, it is still a challenge to achieve water-induced recovery afterglow materials, and materials can maintain afterglow after prolonged contact with water. Herein we show that a RTP-silent metal-organic framework (MOF), MOF-5, can immediately emit green RTP upon water stimulation. Detailed studies show water causes transformation of MOF-5 into another more tightly packed framework. Besides, strong hydrogen bond network is constructed by H2O molecules trapped in the channels. Both factors limit the motion of the ligand and stabilize the triplet state, resulting in RTP. Such structural transformation can be further used as a new doping strategy to prepare a series of water-awakened RTP phosphor@MOF composites with RTP color ranging from green to orange-red and durations of 3–6 s. Remarkably, the RTP of the composites can maintain at least six weeks when being soaked in water. Water-induced information encryption based on the composites has been demonstrated. This work not only sheds new light on the developing of water-friendly MOF-based RTP materials, but also provides a new strategy for the preparation of doped afterglow materials.