合肥工业大学朱元元团队报道了基于联吡啶-双(恶唑啉/噻唑啉)四齿配体中调谐镧系发光。相关研究成果发表在2024年5月28日出版的《结构化学》。

有机配体作为能量吸收和转移的敏化剂，在镧系元素发光中发挥着关键作用，这种现象被称为荧光天线效应。

该文中，研究人员介绍了两种四齿氮配体，它们以对镧系元素发光的高效敏化而闻名，通过对其结构的细微修改，它们的发光效率可以微调。通过这些配体与三氟磺酸铕/铽的络合，合成了四种Eu（III）/Tb（III）单核配合物，即6,6'-双（4,5-二氢恶唑-2-基）-2,2'-联吡啶（L¹）和6,6'--双（4,5--二氢噻唑-2-基）-2，2'-联吡啶（L²）。结构分析表明，镧系元素离子与来自两个配体的八个氮原子和来自三氟磺酸酯的一个氧原子配位。

在这些配合物中，两个Eu（III）配合物（EuL¹和EuL²）和一个Tb（III）复合物（TbL¹）表现出光度，显示出具有高荧光量子产率和延长激发态寿命的镧系金属离子发光特性。相反，TbL²是不发光的，唯一的结构区别是配体内氧原子被硫原子取代。这种微小的变化显著影响配体的三重态能级（3T），从而影响它们对Tb（III）发光的敏化作用。

这些发现强调了bpybox型配体作为Ln（III）发光敏化剂的显著效率，其结构的多功能性使得能够有效地调节发光容量和效率。

附：英文原文

Title: Tunning lanthanide luminescence from bipyridine-bis(oxazoline/thiazoline) tetradentate ligands

Author: Hao Jiang, Yuan-Yuan He, Hai-Chao Liang , Meng-Jia Shang , Han-Han Lu, Chun-Hua Liu, Yin-Shan Meng, Tao Liu, Yuan-Yuan Zhu

Issue&Volume: 2024-05-28

Abstract: Organic ligands play a pivotal role in lanthanide luminescence by acting as sensitizers for energy absorption and transfer, a phenomenon known as the fluorescence antenna effect. Herein, we introduce two tetradentate nitrogen ligands renowned for their efficient sensitization of lanthanide luminescence, with their luminous efficacy finely adjustable through subtle modifications to their structure. Through the synthesis of four Eu(III)/Tb(III) mononuclear complexes via the complexation of these ligands, namely 6,6'-bis(4,5-dihydrooxazol-2-yl)-2,2'-bipyridine (L1) and 6,6'-bis(4,5-dihydrothiazol-2-yl)-2,2'-bipyridine (L2), with europium/terbium trifluorosulfonate. Structural analysis reveals that the lanthanide ion coordinates with eight nitrogen atoms from two ligands and one oxygen atom from trifluorosulfonate. Among these complexes, two Eu(III) complexes (EuL1 and EuL2) and one Tb(III) complex (TbL1) exhibit luminosity, displaying characteristic lanthanide metal ion luminescence characterized by high fluorescence quantum yields and prolonged excited state lifetimes. In contrast, TbL2 is non-luminous, with the sole structural distinction being the substitution of oxygen atoms with sulfur atoms within the ligand. This minor alteration significantly impacts the triplet state energy level (3T) of the ligands, thereby influencing their sensitizing effect on Tb(III) luminescence. These findings underscore the remarkable efficiency of bpybox-type ligands as sensitizers for Ln(III) luminescence, with their structural versatility enabling effective modulation of luminous capacities and efficiency.

DOI: 10.1016/j.cjsc.2024.100354

Source: http://cjsc.ac.cn/cms/issues/634