Near-IR emission of Nd(III) encaged in nanosized zeolites

The near-IR emission of Nd(III) with the highest quantum yield (9.5%) in organic media was successfully observed for the first time by using bis-(perfluoromethylsulfonyl)amide (PMS) as a low vibrational ligand of the ion and TMA⁺-containing FAU zeolite nanocrystallites (TMA-nanoFAU) as a host matrix. Treatments such as deuteration and thermal treatments at high temperatures were ineffective for the strong emission of Nd(III) within TMA-nano-FAU. Judd-Ofelt analysis revealed that the ligation of PMS with the Nd(III) ion occurred easily, because the ions remained in the super cages without migrating into inner cages due to the hindrance of TMA⁺ ions occupying in the sodalite cages. The emission intensity of TMA-nano-FAU treated with PMS increased with the Nd(III)-loading level. The emission decays did not follow simple first-order kinetics and the average lifetime became longer with increasing Nd(III)-loading level. The short lifetimes at low loading levels and the long lifetimes at high loading level were attributed to Nd(PMS)₃ complexes formed with coordinating water molecules and Nd(PMS)]-zeolite complexes without coordinating water molecules, respectively.