Two Penta-REIII Encapsulated Tetravacant Dawson Selenotungstates and Nanoscale Derivatives and Their Luminescence Properties.

Two penta-REIII encapsulated tetravacant Dawson selenotungstates [H2N(CH3)2]10H3[SeO4RE5(H2O)7(Se2W14O52)2]·40H2O (RE = Dy3+ (1), Gd3+ (2)) were prepared by a one-step assembly strategy under bench conditions. Notably, the penta-REIII-substituted [SeO4RE5(H2O)7(Se2W14O52)2]12- polyoxoanion consists of two equivalent tetravacant Dawson [Se2W14O52]12- fragments linked by a central penta-REIII {SeO4RE5(H2O)7} cluster through 16 lacunary oxygen atoms and four bridging oxygen atoms from two [Se2W14O52]12- fragments. Furthermore, a series of cetyltrimethylammonium bromide (CTABr) encapsulated 1@CTA nanomaterials were prepared by the microwave method by controlling different reaction times and temperatures. The effects of time and temperature on the morphologies of 1@CTA nanomaterials were characterized by SEM images, and 1@CTA-5min prepared at 80 °C has a relatively uniform size of about 190 nm. Moreover, the photoluminescence properties of 1 and 1@CTA nanomaterials were investigated systematically, indicating that 1@CTA-5min prepared at 80 °C exhibits the strongest emission due to its smallest size and high dispersion. The energy transfer from the ST fragments to Dy3+ ions in 1 and 1@CTA-5min were proved by time-resolved emission spectra (TRES) and the change in CIE coordinates with increasing time, and their energy transfer mechanism diagram was demonstrated.