Broadly excited red long persistent luminescence from hetero-ligand MOFs

Abstract

Metal–organic frameworks (MOFs) have been considered as ideal platforms to achieve long persistent luminescence (LPL), to utilize as optical recording devices, security systems and sensors. Despite the rapid emergence, it is still a challenge to develop single-component red LPL MOFs. In this work, two hetero-ligand MOFs are synthesized using a D–π–A-type ligand (source of red phosphorescence) and a monocyclic carboxylic ligand (appropriate void constructer), which show efficient red LPL after removal of wide excitations at ambient conditions. Experiment and calculation suggest that the effective red LPL originates from the D–π–A-type ligand, while the auxiliary carboxylic ligand mediates the orientation/arrangement of the D–π–A linker in MOFs affecting phosphorescence. The MOFs are further used in the field of multiple message encryption, initiating a new perspective for designing new red LPL MOFs.