Molecular Upconversion in Water in Heteropolynuclear Supramolecular Tb/Yb Assemblies

Aline Nonat (1) , Sylvana Bahamyirou (2) , Alexandre Lecointre (2) , Frederic Przybilla (3) , Yves Mely (3) , Carlos Platas-Iglesias (4) , Franck Camerel (5) , Olivier Jeannin (5) , Loïc J. Charbonnière (2)

1 DSA-IPHC - Département Sciences Analytiques et Interactions Ioniques et Biomoléculaires
2 IPHC - Institut Pluridisciplinaire Hubert Curien
3 LBP - Laboratoire de Bioimagerie et Pathologies
4 Universidade da Coruña
5 ISCR - Institut des Sciences Chimiques de Rennes

Piling up excited states to reach upconversion (UC) is severely restricted by vibrational quenching mechanisms, especially when one looks at discrete molecular entities in solution. By carefully controlling the supramolecular assembly processes resulting from the strong electrostatic interactions between negatively charged Yb complexes and Tb3+ cations in aqueous solutions, we engineered the formation of heteropolynuclear complexes of [(YbL)(2)Tb-x] compositions (x = 1 and 2). These edifices display a phenomenon of cooperative photosensitization UC with green emission of the Tb cations upon NIR excitation at 980 nm in the Yb absorption band. The photophysical properties of the complexes were carefully investigated by steady-state and time-resolved luminescence quantify the impact of the composition and pD of the solution on the emission intensity as well as clarifying the exact cooperative photosensitization upconversion mechanism. Using optimized conditions, the energy transfer UC process could be observed for the first time in nondeuterated water with discrete molecular compounds.

Domains: Chemical Sciences; Coordination chemistry

Aline Nonat, Sylvana Bahamyirou, Alexandre Lecointre, Frederic Przybilla, Yves Mely, et al.. Molecular Upconversion in Water in Heteropolynuclear Supramolecular Tb/Yb Assemblies. Journal of the American Chemical Society, 2019, 141 (4), pp.1568-1576. ⟨10.1021/jacs.8b10932⟩. ⟨hal-02049516⟩