Giant 3d‐4f Heterometallic Polyoxoniobates of {Na₂Zn₂₉Ln₁₂Nb₁₂₂}, {Zn₁₀Eu₈Nb₆₀}, and {Zn₁₆Ln₈Nb₈₈} with Photonic Barcodes

The integration of the rich electronic properties of 3d-4f heterometallic clusters with rigid and diamagnetic polyoxometalates is of great interest and is expected to yield novel materials with enhanced properties due to synergistic effects. For the first time, the study succeeds in introducing fluorescent Zn-Ln heterometallic clusters into polyoxoniobates (PONbs), forming a family of rare giant heterometallic PONbs with various architectures, including 78-metal {Zn₁₀Eu₈Nb₆₀}, 112-metal {Zn₁₆Ln₈Nb₈₈} (Ln = La, Y), and 165-metal {Na₂Zn₂₉Ln₁₂Nb₁₂₂} (Ln = Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho). These heterometallic PONbs exhibit many appealing structural features and unique building blocks. Particularly, they are the largest 3d-4f heterometallic PONbs and also the PONbs incorporating the largest number of 3d-4f metal ions and the highest-nuclearity 3d-4f clusters known to date. Furthermore, the combination of PONbs and Zn-Ln clusters renders these new-type heterometallic PONbs multicolor luminescent characteristics and high fluorescence quantum yields, making them promising candidate cluster molecules for responsive photonic barcodes.