Acetate-Decorated Tri-Ln(III)-Containing Antimonotungstates with a Tetrahedral {WO} Group as a Structure-Directing Template and Their Luminescence Properties.

Four acetate-decorated tri-Ln-substituted trimeric antimonotungstates (AMTs) Na{(WO)[Ln(HO)(Ac)(B-α-SbWO(OH))]}·50HO [Ln = Eu (), Dy (), Ho (), or Gd ()] were isolated by reaction of Na[B-α-SbWO]·19.5HO, NaWO·2HO, and Ln(NO)·6HO in a HAc/NaAc buffer solution. Interestingly, a tetrahedral {WO} group plays a significant structure-directing template role in the formation of their polyoxoanions. With regard to luminescence properties, with a change in the excitation wavelength, it is available to switch emission colors from orange to red for , blue to green for , and blue to yellow for . Under the O → W LMCT excitation, energy transfer from AMT fragments to Eu, Dy, and Ho ions occurs because Ln ions can absorb energy from O → W LMCT emission of AMT segments. The temperature-dependent luminescence behaviors (25-720 °C) of together with auxiliary emitting photographs illustrate that the growing emission in the temperature range of 25-100 °C results from the loss of lattice water molecules, the decline of emission between 100 and 320 °C may occur because crystals become amorphous powders, the slow emission decay (220-320 °C) is due to the case that the emission enhancement derived from the removal of water ligands on Eu ions in some degree compensates for the decline of emission intensity, the sharp decrease in emission (320-520 °C) may result from the change in the coordinate environment of Eu ions, and the weak recovery of emission (620-720 °C) may be ascribed to the formation of new phase NaEuWO. This work lays a significant foundation for preparing novel POM-based luminescent materials.