Multi-NIR-Emissive Materials based on Heterolanthanide Molecular Assemblies

Abstract

Er_xYb_(3−x)Q₉ (1, x = 1, 2), NdYb₂Q₉ (2), NdEr₂Q₉ (3) and NdErYbQ₉ (4), have been obtained through a simple molecular strategy, by controlling reactant stoichiometry. In 2–4, the templating effect of the molecular framework allows to control the metal distribution across the coordination sites where the central position is occupied by the larger Nd ion and the terminal ones by the almost vicariants Yb³⁺ and Er³⁺, drastically reducing molecular speciation. Remarkably, 4 represents the first example of a discrete molecular entity containing three different Ln ions simultaneously emitting in three different spectral regions in the NIR, upon single visible wavelength excitation. Highly transparent and homogeneous doped silica glasses have been prepared, which show the same optical properties of the incorporated complex in solution.