Photoluminescence and Hydrothermal Stability Correlations via Isoreticular/Structural fcu Rare-Earth Organic Frameworks Platform

Abstract

Because of the discovery of a high-symmetry rare-earth hexanuclear secondary building unit, controllable design and assembly of rare-earth organic frameworks (REOFs) have become feasible. Subsequently, series of isoreticular/structural fcu REOFs platform was herein successfully produced by solvothermal reactions and reticular chemistry. After the crystal structural information and permanent porosity were confirmed, thorough investigations toward photoluminescence and hydrothermal stability were implemented. As a result, distinct and interesting luminescence behavior is observed among the series of REOFs. 1-Dy and 2-Dy mainly display ligand-centered emission, while 1-Eu and 2-Eu are predominated by metal-centered emission. More interestingly, 1-Eu reveals excitation dependent luminescence, generating the first example of a white light emission phosphor in single phase fabricated from a sole Eu3+ ion and sole organic linker. 2-Eu however does not exhibit such features and stays mostly unchanged upon the variation of excitation light. The above luminescence features were correlated by determination of the triplet state T1 energy of both L1 and L2 linkers via the phosphorescence at 77 K of 1-Gd and 2-Gd. Lastly, water resistance of the series of fcu REOFs was valued and it was found that 1-Dy constructed from a smaller ion radius and shorter organic linker exhibits the most prominent hydrothermal stability among the series of REOF platforms.