The luminescence properties of lanthanoid ions can be dramatically enhanced by coupling them to antenna ligands that absorb light in the UV-visible and then efficiently transfer the energy to the lanthanoid centre. The synthesis and the complexation of Ln^III cations (Ln = Eu, Gd) for a ligand based on four 1-hydroxy-2-pyridinone (1,2-HOPO) chelators appended to a ligand backbone derived by linking two l-lysine units (3LI-bis-LYS) is described. This octadentate Eu^III complex ([Eu(3LI-bis-LYS-1,2-HOPO)]^–) has been evaluated in terms of its thermodynamic stability, UV-visible absorption and luminescence properties. For this complex, the conditional stability constant (pM) is 19.9, which is an order of magnitude higher than diethylenetriaminepentacetic acid at pH = 7.4. This Eu^III complex also shows an almost two-fold increase in its luminescence quantum yield in aqueous solution (pH = 7.4) when compared with other octadentate ligands. Hence, despite a slight decrease of the molar absorption coefficient, a much higher brightness is obtained for [Eu(3LI-bis-LYS-1,2-HOPO)]^–. This overall improvement was achieved by saturating the coordination sphere of the Eu^III cation, yielding an increased metal-centred efficiency by excluding solvent water molecules from the metal’s inner sphere.

通过将镧系元素离子与吸收紫外可见光的天线配体耦合，然后有效地将能量转移到镧系元素中心，可以显着增强镧系元素离子的发光特性。 Ln ^III阳离子 (Ln = Eu, Gd) 的合成和络合，用于基于四个 1-羟基-2-吡啶酮 (1,2-HOPO) 螯合剂的配体，该螯合剂附加到通过连接两个l-赖氨酸单元衍生的配体主链上描述了(3LI-二-LYS)。这种八齿 Eu ^III配合物 ([Eu(3LI-bis-LYS-1,2-HOPO)] ^– ) 的热力学稳定性、紫外-可见光吸收和发光性能均经过评估。对于该复合物，条件稳定性常数 (pM) 为 19.9，比 pH = 7.4 时的二亚乙基三胺五乙酸高一个数量级。与其他八齿配体相比，该 Eu ^III配合物在水溶液（pH = 7.4）中的发光量子产率几乎增加了两倍。因此，尽管摩尔吸收系数略有下降，[Eu(3LI-bis-LYS-1,2-HOPO)] ^–却获得了更高的亮度。这种整体改进是通过使 Eu ^III阳离子的配位球饱和来实现的，通过从金属内球中排除溶剂水分子来提高金属中心效率。