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

} (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.