Encapsulation of Ln3+hydrate species for tunable luminescent materials based on a porous Cd(ii)-MOF

Abstract

This work builds on the recently developed guest-driven approach for the construction of tunable luminescent materials based on porous metal–organic frameworks (MOFs). The porous heteroatom-rich Cd(II)-MOF (1) material has been obtained by the reaction of Cd(NO₃)₂ with 3,5-bis(3-carboxyphenyl)-1,2,4-triazole)/4,4′-bis(4-pyridyl)ethane in solution. Compound 1 features (4,4) sheets which interlock together to generate a 2-fold interpenetrating robust framework containing ellipse-like channels with pore dimensions of ca. 9 × 11 Å. In particular, 1 is able to trap lanthanide hydrate cationic species such as Eu(H₂O)₈³⁺ and Tb(H₂O)₈³⁺ and to sensitize their emissions in the solid state. Furthermore, the emission colors could be tuned by changing the co-doped Eu³⁺/Tb³⁺ ratio in the Cd(II)-MOF to provide barcode-like luminescent materials.