Godec Léna, Knighton Richard C, Hamon Nadège, Thor Waygen, Wong Ka-Leung, Tripier Raphaël, Charbonnière Loïc J
Equipe de Synthèse pour l'Analyse (SynPA), IPHC, UMR 7178, CNRS/Université de Strasbourg, ECPM, 25 Rue Becquerel, 67087 Strasbourg Cedex, France.
School of Chemistry and Chemical Engineering, University of Southampton, Southampton, SO17 1BJ, U.K.
J Am Chem Soc. 2025 Aug 27;147(34):31187-31197. doi: 10.1021/jacs.5c09915. Epub 2025 Aug 13.
We report the synthesis of a tritopic ligand, , composed of two strongly binding lanthanide (Ln) sites using tris-functionalized triazacyclononane (tacn) scaffolds bridged by a weaker Ln binding triethylene glycol chain. Coordination chemistry of Ln (Ln = Eu, Tb, Yb, Lu) was investigated by using NMR and photoluminescent spectroscopies. The first two Ln ions are coordinated by the tacn scaffolds to form [Ln] and [Ln] species, followed by tri- and tetranuclear complexes, [Ln(Ln)] and [Ln(Ln)]. The third and fourth exomacrocyclic binding events occur at the polyethylene glycol binding site, buttressed by a synergistic interaction of the phosphonate arms, confirmed by DFT modeling. [Ln] (Ln = Tb, Eu, Yb, and Lu) homobimetallic complexes were prepared, and characterized and their spectroscopic properties determined in HO and DO. Titration of the [Yb] dinuclear complex by Tb salts in DO confirmed the formation of the tri- and tetranuclear species. Upon excitation into the F ← F absorption band of Yb at 980 nm, a cooperative sensitization upconversion process is evidenced, displaying visible Tb emission bands. Heating resulted in Ln scrambling in the tacn coordination sites, increasing the UC efficiency by ca. 10. The most efficient emitter for UC is the tetranuclear [TbYb(TbYb)], with one of each Ln species in the tacn scaffolds and one of each Ln species coordinated by the polyethylene glycol chain. Optimization on the pD led to an overall 9.0 × 10 UC quantum yield (λ = 980 nm, = 10.8 W·cm). The same experiment was repeated in water, affording UC at the molecular level.
我们报道了一种三齿配体的合成，该配体由两个强结合的镧系（Ln）位点组成，使用三官能化的三氮杂环壬烷（tacn）支架，通过较弱的Ln结合三甘醇链桥连。通过核磁共振（NMR）和光致发光光谱研究了Ln（Ln = Eu、Tb、Yb、Lu）的配位化学。前两个Ln离子由tacn支架配位形成[Ln]和[Ln]物种，随后是三核和四核配合物，[Ln(Ln)]和[Ln(Ln)]。第三和第四次大环外结合事件发生在聚乙二醇结合位点，由膦酸酯臂的协同相互作用支撑，这通过密度泛函理论（DFT）建模得到证实。制备了[Ln]（Ln = Tb、Eu、Yb和Lu）同双核配合物，并进行了表征，测定了它们在H₂O和D₂O中的光谱性质。在D₂O中用Tb盐滴定[Yb]双核配合物证实了三核和四核物种的形成。在980 nm激发Yb的F ← F吸收带时，证明了一个协同敏化上转换过程，显示出可见的Tb发射带。加热导致tacn配位位点中的Ln发生重排，使上转换效率提高约10倍。用于上转换的最有效发射体是四核[TbYb(TbYb)]，其中每个tacn支架中有一个每种Ln物种，并且每种Ln物种中有一个由聚乙二醇链配位。对pD进行优化得到了9.0×10⁻⁶的上转换量子产率（λ = 980 nm，I₀ = 10.8 W·cm⁻²）。在水中重复相同的实验，在分子水平上实现了上转换。
