Upconversion in a d–f [RuYb<sub>3</sub>] Supramolecular Assembly
Richard C. Knighton, Lohona K. Soro, Waygen Thor, Jean‐Marc Strub, Sarah Cianférani, Yves Mély, Marc Lenertz, Ka‐Leung Wong, Carlos Platas‐Iglesias, Frédéric Przybilla, Loı̈c J. Charbonnière
Abstract
We have prepared a hetero-tetrametallic assembly consisting of three ytterbium ions coordinated to a central [Ru(bpm)3]2+ (bpm = 2,2′-bipyrimidine) motif. Irradiation into the absorption band of the peripheral ytterbium ions at 980 nm engenders emission of the 3MLCT state of the central [Ru(bpm)3]2+ core at 636 nm, which represents the first example of f → d molecular upconversion (UC). Time-resolved measurements reveal a slow rise of the UC emission, which was modeled with a mathematical treatment of the observed kinetics according to a cooperative photosensitization mechanism using a virtual Yb centered doubly excited state followed by energy transfer to the Ru centered 1MLCT state.