Aboshyan-Sorgho, LilitNozary, HomayounAebischer, AnninaBünzli, Jean-Claude G.Morgantini, Pierre-YvesKittilstved, Kevin R.Hauser, AndreasEliseeva, Svetlana V.Petoud, StéphanePiguet, Claude2013-01-152013-01-15201210.1021/ja304009bhttps://infoscience.epfl.ch/handle/20.500.14299/87850WOS:000306942600062This work illustrates a simple approach for optimizing long-lived near-infrared lanthanide-centered luminescence using trivalent chromium chromophores as sensitizers. Reactions of the segmental ligand L2 with stoichiometric amounts of M(CF3SO3)(2) (M = Cr, Zn) and Ln(CF3SO3)(3) (Ln = Nd, Er, Yb) under aerobic conditions quantitatively yield the D-3-symmetrical trinuclear [MLnM(L2)(3)](CF3SO3)(n) complexes (M = Zn, n = 7; M = Cr, n = 9), in which the central lanthanide activator is sandwiched between the two transition metal cations. Visible or NIR irradiation of the peripheral Cr(III) chromophores in [CrLnCr(L2)(3)](9+) induces rate-limiting intramolecular intermetallic Cr -> Ln energy transfer processes (Ln = Nd, Er, Yb), which eventually produces lanthanide-centered near-infrared (NIR) or IR emission with apparent lifetimes within the millisecond range. As compared to the parent dinuclear complexes [CrLn(L1)(3)](6+), the connection of a second strong-field [CrN6] sensitizer in [CrLnCr(L2)(3)](9+) significantly enhances the emission intensity without perturbing the kinetic regime. This work opens novel exciting photophysical perspectives via the buildup of non-negligible population densities for the long-lived doubly excited state [Cr*LnCr*(L2)(3)](9+) under reasonable pumping powers.text::journal::journal article::research article