Extending Lifetimes of Lanthanide-Based Near-Infrared Emitters (Nd, Yb) in the Millisecond Range through Cr(III) Sensitization in Discrete Bimetallic Edifices

A [Cr(α,α‘-diimine)3]3+ chromophore is used as a donor for sensitizing NdIII and YbIII near-infrared (NIR) emitters in the heterobimetallic helicates [LnCrIIIL3]6+. The intramolecular CrIII → LnIII energy transfer process controls the population of the lanthanide-centered emitting levels, thus leading to unprecedented extension of the NIR luminescence decay times in the millisecond range for Nd and Yb ions incorporated in coordination complexes.