Lanthanide-Based Molecular Cluster-Aggregates: Optical Barcoding and White-Light Emission with Nanosized {Ln₂₀ }...

Counterfeit goods represent a major problem to companies, governments, and customers, affecting the global economy. In order to protect the authenticity of products and documents, optical anti-counterfeit technologies have widely been employed via the use of discrete molecular species, extended metal-organic frameworks (MOFs), and nanoparticles. Herein, for the first time we demonstrate the potential use of molecular cluster-aggregates (MCA) as optical barcodes via composition and energy transfer control. The tuneable optical properties for the [Ln₂₀ (chp)₃₀ (CO₃ )₁₂ (NO₃ )₆ (H₂ O)₆ ], where chp^- =deprotonated 6-chloro-2-pyridinol, allow the fine control of the emission colour output, resulting in high-security level optical labelling with a precise read-out. Moreover, a unique tri-doped composition of Gd^III , Tb^III , and Eu^III led to MCAs with white-light emission. The presented methodology is a unique approach to probe the effect of composition control on the luminescent properties of nanosized molecular material.