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 (TbxM1-x)2(1,4-bdc)3 center dot 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<middle dot>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.