Inorganic Building Unit Isomerization Engineering for Multicolor Room Temperature Phosphorescence

Room temperature phosphorescence (RTP) materials have gained significant attention in current research. However, facile regulation of RTP color remains a great challenge. Here an "inorganic building unit (IBU) isomerization engineering" strategy is proposed to facilely regulate RTP color. Four coordination polymers (CPs) with different packing structures from the same raw material are prepared. Among them, 1 has a 2D layered structure, while 2, 3, and 4 can be viewed as 3D framework isomers, which display a wide-range of RTP colors (505-612 nm) ranging from cyan to red, and the optimal RTP excitation wavelengths for 3 and 4 are both located within the visible light region. Detailed investigation reveals that the IBU isomerization effectively regulates the interaction between organic linkers, leading to different charge transfer (CT) processes and inducing various RTP emission. Additionally, color-tunable doped RTP materials with calcium formate as matrix and in-situ formed 4 as guest components are prepared, exhibiting interesting excitation/ concentration/ time-dependent RTP emission. Finally, the potential application of the materials in multi-level information encryption is demonstrated. This study not only proposes an effective method for regulating RTP color, but also highlights the great potential of CP-type guest components in preparing doped RTP materials.