Three Types of Lanthanide-Containing Polyoxoniobates and Their Luminescence Properties

Fourteen lanthanide (Ln)-containing hetero selenato-phosphato-peroxopolyoxoniobates in three series: (1) Cs2{[Ln­(H2O)4]­[H4P2Se2Nb6(O2)6O22]}2·nH2O [Ln = Ce (I-Ce), Pr (I-Pr), Sm (I-Sm), Eu (I-Eu), Gd (I-Gd); I-Ce, I-Pr, I-Eu, I-Gd n = 12; I-Sm n = 16]; (2) Cs2K3{[Ln­(H2O)6]­[H2.5P2Se2Nb6(O2)6O22]}2·nH2O [Ln = Dy (II-Dy), Tm (II-Tm), Yb (II-Yb), Lu (II-Lu); II-Dy n = 14; II-Tm n = 24; II-Yb, II-Lu n = 13]; (3) Cs5K2H m {[Ln­(H2O)6]­[P2Se2Nb6(O2)6O22]}2{[Ln x (H2O) y ]2[P2Se2Nb6(O2)6O22]}·nH2O [Ln = Ho (III-Ho), Er (III-Er), Tm (III-Tm), Yb (III-Yb), Lu (III-Lu), III-Ho-III-Yb m = 5, x = 1; y = 5; III-Lu m = 6.5; x = 0.75; y = 4; III-Ho–III-Tm n = 19, III-Yb n = 34; III-Lu n = 31], have been isolated by a one-pot reaction and structurally characterized by various physical and chemical analyses. These compounds represent the first group of Ln-functionalized polyoxoniobates with mixed heteroatoms. In addition, the photoluminescence properties of compounds I-Sm, I-Eu, and II-Dy were measured, and the time-resolved emission spectra showed that the {P2Se2Nb6} segment contributed to the energy transfer from the polyoxoniobate units to the Ln3+ center, which effectively promoted the emission of the Ln3+ center.