Untapped potentials of lanthanide‐based molecular cluster‐aggregates: Optical barcoding and white‐light emission with nanosized {Ln20} compound

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 have widely been employed via the use of discrete molecular species, extended metal-organic frameworks, 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 tunable optical properties for the [Ln 20 (chp) 30 (CO 3 ) 12 (NO 3 ) 6 (H 2 O) 6 ], where chp - = deprotonated 6-chloro-2-pyridinol, allow the fine control of the emission color 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.