Tetranuclear lanthanide-based silsesquioxanes: towards a combination of a slow relaxation of the magnetization and a luminescent thermometry

Lanthanide-based silsesquioxanes constitute an emerging family of cage-like metallasilsesquioxanes with exciting optical and magnetic properties. We report here the synthesis, structures and luminescence properties of a series of tetranuclear lanthanide-silsesquioxane compounds of general formula [NEt4]2[(Ph4Si4O8)2(Ln/Ln & PRIME;)4(NO3)6(EtOH)2(MeCN)2]& BULL;4(MeCN) with different lanthanide ions (where Ln/Ln & PRIME; = Dy3+/Eu3+ (1), Dy3+/Tb3+ (2) and Eu3+/Tb3+/Y3+ (3)) and investigate the impact of the lanthanide ions combination on magnetic and photo-luminescent properties. Compound 1 behaves as a field-induced Single Molecule Magnet (SMM) and presents temperature-dependent luminescence characteristics of Eu3+ making it an emissive thermometer working in the temperature range 293-373 K with the maximum relative sensitivity of 1.15% K-1 achieved at 293 K. Compounds 2 and 3 are paramagnets, which demonstrate a characteristic photoluminescence with Dy3+ to Tb3+ and Tb3+ to Eu3+ energy transfers, respectively. Mixed-lanthanide silsesquioxane cages: to combine a slow relaxation of the magnetization and a luminescent thermometry.

Automated summary

In this article, the synthesis, structures, and luminescent properties of a series of tetranuclear lanthanide-silsesquioxane compounds were reported. The impact of different combinations of lanthanide ions on magnetic and photo-luminescent properties was investigated.