The Structure and Optical Properties of Luminescent Terbium Terephthalate Metal–Organic Frameworks Doped with Yttrium, Gadolinium, and Lanthanum Ions.

The structural features and luminescent properties of heterometallic Tb–Gd, Tb–La, and Tb–Y terephthalate metal–organic frameworks, namely (Tb_xM_1−x)₂(1,4-bdc)₃∙4H₂O (M = Gd, La, Y), were studied in detail in a wide concentration range (x = 0.001–1). The crystalline phase of synthesized compounds corresponds to Ln₂(1,4-bdc)₃·4H₂O. The lifetime of ⁵D₄ decreased with increased Tb³⁺ concentration, but PLQY depends non-linearly on the Tb³⁺ concentration. The 50% substitution of Tb³⁺ for Y³⁺, Gd³⁺, or La³⁺ ions result in the significant enhancement of photoluminescence quantum yield, up to 1.6 times. The morphology, thermal stability, and vibrational structure of the selected homo- and bi-metallic materials is reported as well. [ABSTRACT FROM AUTHOR]