Yb-to-Eu Cooperative Sensitization Upconversion in a Multifunctional Molecular Nonanuclear Lanthanide Cluster in Solution
Sai P. K. Panguluri, Elsa Jourdain, Papri Chakraborty, Svetlana Klyatskaya, Manfred M. Kappes, Aline Nonat, Loı̈c J. Charbonnière, Mario Ruben
Abstract
Lanthanide metal clusters excel in combining molecular and material chemistry properties. Here, we report an efficient cooperative sensitization UC phenomenon of a Eu 3+ /Yb 3+ nonanuclear lanthanide cluster in CD 3 OD. The synthesis and characterization of the heteronuclear cluster in the solid state and solution are described together with the UC phenomenon showing Eu 3+ luminescence in the visible region upon 980 nm NIR excitation of Yb 3+ at concentrations as low as 100 nM. Alongside being the Eu/Yb cluster to display UC (with a quantum yield value of 4.88 × 10 –8 upon 1.13 W cm –2 excitation at 980 nm), the cluster exhibits downshifted light emission of Yb 3+ in the NIR region upon 578 nm visible excitation of Eu 3+, which is ascribed to sensitization pathways for Yb through the 5 D 0 energy levels of Eu 3+ . Additionally, a faint emission is also observed at ca. 500 nm upon 980 nm excitation, originating from the cooperative luminescence of Yb 3+ . The [Eu 8 Yb(BA) 16 (OH) 10 ]Cl cluster (BA = benzoylacetonate) is also a field-induced single-molecular magnet (SMM) under 4K with a modest U eff / k B of 8.48 K, thereby joining the coveted list of Yb-SMMs and emerging as a prototype system for next-generation devices, combining luminescence with single-molecular magnetism in a molecular cluster.