Achieving stable photoluminescence by double thiacalix[4]arene-capping: the lanthanide-oxo cluster core matters.

Luminescence stability is a critical consideration for applying phosphors in practical devices. In this work, we report two categories of double -butylthiacalix[4]arene (HTC4A) capped clusters that exhibit characteristic lanthanide luminescence. Specifically, {[Ln(μ-OH)(TC4A)(DMF)(CHOH)(HCOO)Cl]}·CHOH (Ln = Eu (1), Tb (2); = 0-1) with square-planar [Ln(μ-OH)] cluster cores and {[Ln(μ-OH)(μ-OH)(OCH) (TC4A) (HO)Cl]}·DMF (Ln = Gd (3), Tb (4), Dy (5); = 2-6) with hourglass-like [Ln(μ-OH)(μ-OH)] cluster cores are synthesized and characterized. By comparing 2 and 4, we find that several critical luminescence properties (such as quantum efficiency and luminescence stabilities) depend directly on the cluster core structure. With the square-planar [Ln(μ-OH)] cluster cores, 2 demonstrates high quantum yield (∼65%) and excellent luminescence stability against moisture, high temperature, and UV-radiation. A white light-emitting diode (LED) with ultrahigh color quality is successfully fabricated by mixing 2 with commercial phosphors. These results imply that high quality phosphors might be achieved by exploiting the double thiacalix[4]arene-capping strategy, with an emphasis on the cluster core structure.