Synthesis, crystal structure and photoluminescence studies of NIR emitting lanthanide-tetrakis-β-diketonate complexes in the solid state.

Here, we report the synthesis and characterization of two new near-infrared (NIR) emitting lanthanide tetrakis-β-diketonate complexes NBu4[LnL4], where L = 1-(4-(9H-carbazol-9-yl)phenyl)-4,4,4-trifluorobutane-1,3-dione and Ln = Er3+ and Yb3+. The crystal structures of these complexes reveal an octa-coordinated tetrakis-β-diketonate coordination environment around the Ln3+ center in a square antiprismatic manner. Photoluminescence studies in the solid state demonstrate NIR emission with the Yb3+ complex exhibiting the 2F5/2 → 2F7/2 transition at around 1 μm and the Er3+ complex exhibiting the 4I13/2 → 4I15/2 transition at around 1.5 μm. NBu4[YbL4] in the solid state shows an average lifetime of 46 μs and an intrinsic quantum efficiency (ϕYb) = 2.2%, whereas the 4I13/2 lifetime of Er3+ in NBu4[ErL4] was found to be 3.7 μs.