A Luminescent Folded S-shaped High-Nuclearity Eu19-oxo-clusters Embedded Polyoxoniobate for Information Encryption

Ln-containing polyoxoniobates (PONbs) have appealing applications in luminescence, information encryption and magnetic fields, but the synthesis of PONbs containing high-nuclearity Ln-O clusters is challenging due to the easy hydrolysis of Ln3+ ions in alkaline environments. In this paper, we are able to integrate CO32− and high-nuclearity Ln-O clusters into PONb to construct an inorganic giant Eu19-embedded PONb H49K16Na13(H2O)63[Eu21O2(OH)7(H2O)5(Nb7O22)10(Nb2O6)2(CO3)18]·91H2O (1), which contains the highest nuclearity Eu-O clusters and the largest number of Eu3+ ions among PONbs. In addition, the film that was prepared by mixing 1 with gelatin and glycerol, exhibits reversible luminescence switching behavior under acid/alkali stimulation and has been used to create a fluorescence-encoded information approach. This work paves a feasible strategy for the construction of high-nuclearity Ln-O cluster-containing PONbs and the expansion of the application of Ln-containing PONbs in information encryption.