Tunable Luminescent Heterometallic Zn₂Ln₂ Edge-Defective Molecular Cubane with Stimuli-Responsive Properties

Heterometallic Zn₂Ln₂ [Ln = Gd (1), Eu (2), Tb (3), Dy (4)] discrete molecules with edge-defective cubane structure are assembled from a multifunctional fluorescent conjugate ligand and Ln^III/Zn^II mixed-metal ions; they exhibit the tunable luminescence, including ligand-based yellow-green light emission for 1 and 4 and lanthanide-center emission for 2 and 3. The multiple stimuli-responsive photoluminescences were investigated to show a two-step thermal-responsive luminescence increase in the intensity upon cooling and piezochromic luminescence.