Europium ions modulated room temperature phosphorescence in dye-encapsulated MOFs for dual-modal fluorescence-afterglow

Abstract

In recent years, room temperature phosphorescence (RTP) materials have attracted widespread attention in the field of materials science due to their exceptional optical properties. In this study, we explore a strategy for RTP by designing and synthesizing metal–organic frameworks (MOFs) based on lutetium (Lu) and finely modulating the photophysical properties of the materials through introduction of europium (Eu). Utilizing the property that formamide generates formic acid under heating conditions, a type of Lu-MOF with formic acid as the sole ligand was successfully synthesized, which opens up a new pathway for the synthesis of MOFs. The phosphorescence intensity and lifetime of the dye 4,4′-bipyridine are significantly enhanced by being encapsulated in the 1D channels of Lu-MOFs. By partially substituting Lu³⁺ with Eu³⁺, we not only adjusted the emission color but also achieved gradient control of fluorescence and phosphorescence intensity, providing precise multilevel optical encoding capabilities for information encryption technologies. This dual-modal fluorescent/phosphorescent MOF system demonstrates high potential for applications in the security field, particularly in the development of advanced anti-counterfeiting and data storage technologies.