Cooperative Sensitization Upconversion in Solution Dispersions of Co‐Crystal Assemblies of Mononuclear Yb3+ and Eu3+ Complexes

Abstract

AbstractLanthanide upconversion luminescence in nanoparticles has prompted continuous breakthroughs in information storage, temperature sensing, and biomedical applications, among others. Achieving upconversion luminescence at the molecular scale is still a critical challenge in modern chemistry. In this work, we explored the upconversion luminescence of solution dispersions of co‐crystals composed of discrete mononuclear Yb(DBM)3Bpy and Eu(DBM)3Bpy complexes (DBM: dibenzoylmethane, Bpy: 2,2′‐bipyridine). The 613 nm emission of Eu3+ was observed under excitation of Yb3+ at 980 nm. From the series of molecular assemblies studied, the most intense luminescence was obtained for a 1 : 1 molar ratio of Yb3+ : Eu3+, resulting in a high quantum yield of 0.67 % at 2.1 W cm−2. The structure and energy transfer mechanism of the assemblies were fully characterized. This is the first example of an Eu3+‐based upconverting system composed of two discrete mononuclear lanthanide complexes present as co‐crystals in non‐deuterated solution.