Nano-Science Center & Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark.
Dalton Trans. 2018 May 29;47(21):7362-7369. doi: 10.1039/c8dt01547c.
In order to reveal subtle differences between the solution chemistries of trivalent 4f and 5f elements, the physicochemical and photophysical properties of europium(iii), terbium(iii) and curium(iii) complexes formed with a 7-methoxy-coumarin appended 1,4,7,10-tetraazadodecane-1,4,7-triacid (DO3A) ligand were studied. All three complexes were found to be kinetically inert and exhibit stability constants similar to their 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) equivalents. The Cm(iii) and Eu(iii) complexes feature strong sensitised emission, while the triplet energy of the coumarin prohibits efficient sensitisation of the Tb(iii) analogue. The data presented here indicate significant differences in perturbation of the sensitising chromophore photophysics between the 4f and 5f elements. In contrast, the size of the metal center appears to not be a determining factor for the physicochemical properties of these kinetically inert Eu(iii), Tb(iii), and Cm(iii) complexes.
为了揭示三价 4f 和 5f 元素在溶液化学上的细微差异，研究了与 7-甲氧基香豆素偶联的 1,4,7,10-四氮杂十二烷-1,4,7,10-四乙酸（DO3A）配体形成的铕（III）、铽（III）和锔（III）配合物的物理化学和光物理性质。所有三种配合物均表现出动力学惰性，且稳定常数与相应的 1,4,7,10-四氮杂环十二烷-1,4,7,10-四乙酸（DOTA）等价物相似。Cm（III）和 Eu（III）配合物具有强烈的敏化发射，而香豆素的三重态能量阻止了 Tb（III）类似物的有效敏化。这里呈现的数据表明，4f 和 5f 元素之间对敏化发色团光物理的干扰存在显著差异。相比之下，金属中心的大小似乎不是这些动力学惰性 Eu（III）、Tb（III）和 Cm（III）配合物物理化学性质的决定因素。
