Structural and Photophysical Studies of Highly Stable Lanthanide Complexes of Tripodal 8-Hydroxyquinolinate Ligands Based on 1,4,7-Triazacyclononane
Structural and Photophysical Studies of Highly Stable Lanthanide Complexes of Tripodal 8-Hydroxyquinolinate Ligands Based on 1,4,7-Triazacyclononane
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DOI：
10.1021/ic9000076
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发表时间：
2009-05-04
影响因子：
4.6
通讯作者：
Mazzanti, Marinella
中科院分区：
文献类型：
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作者：
Nonat, Aline;Imbert, Daniel;Mazzanti, Marinella
三脚架H（3）thqtcn配体允许合成定义明确的中性单体顺式三（羟基喹啉）镧系元素配合物。合成了三重去质子化配体thqtcn（3-）的[Ln（thqtcn）]配合物（Ln = Nd，1; Er，2; Yb，3）。对配合物1和3进行了晶体学表征，结果表明配体具有足够的灵活性，可以用三帽三角棱柱配位几何形状包裹不同尺寸的Ln（III）。部分质子化的H（1.5）thqtcn（1.5-）配体也在甲醇和水（pH类似于5）中与Ln（III）离子强烈结合。X-射线衍射研究表明，质子化配合物结晶为式[Ln（H（1.5）thqtcn）]（2）（OTf）（3）中心点3 MeOH（Ln = Nd，4; Yb，5）的手性二聚体，其中部分质子化的H（1.5）thqtcn（1.5-）的两个等价的单体配合物通过酚氧原子之间非常强的氢键桥接。配体thqtcn（3-）对Er、Nd（0.10%Qy）和Yb（0.60%Qy）的近红外发射有很好的增敏作用。首次通过观察到[Yb（H（1.5）thqtcn）]（2）（OTf）（3）（0.26%）相对于[Yb（thqtcn）]（0.60%）的发光量子产率的降低证明了配体质子化对镧系元素配合物的固态发光效率的影响。合成了H（3）thqtcn及其镧系配合物的水溶性H（3）thqtcn-SO_3类似物。溶液量子产率的thqtcn-SO_（33）-配合物在水中在pH 7.4（0.016%的Nd-III和0.14%的Yb-III）和在氘代水（Nd，0.047%; Yb，0.55%）中测量，并且它们是在文献中报道的Yb-III在水溶液中的最高量子产率之一。thqtcn-SO_3 ~（3-）和thqtcn-SO_3 ~（3-）的镧系元素配合物在生理pH下在水中的高热力学和动力学稳定性表明，thqtcn（3-）和thqtcn-SO_3 ~（3-）的镧系元素配合物高度抗水解，因此非常适合于开发发光器件和用作生物医学成像中的探针。
The tripodal H(3)thqtcn ligand allows the synthesis of well-defined neutral monomeric syn-tris(hydroxyquinolinate) complexes of lanthanides. Pure [Ln(thqtcn)] complexes (Ln = Nd, 1; Er, 2; Yb, 3) of the triply deprotonated ligand thqtcn(3-) were prepared. Crystallographic characterization was carried out for complexes 1 and 3, showing that the ligand is flexible enough to wrap around Ln(III) of different size with a tricapped trigonal-prism coordination geometry. The partially protonated H(1.5)thqtcn(1.5-) ligand also binds strongly to Ln(III) ions in methanol and water (at pH similar to 5). The X-ray diffraction study shows that protonated complexes crystallize as chiral dinners of formula [Ln(H(1.5)thqtcn)](2)(OTf)(3)center dot 3MeOH (Ln = Nd, 4; Yb, 5) in which two equivalent monomeric complexes of the partially protonated H(1.5)thqtcn(1.5-) are bridged by very strong hydrogen bonds between the phenol oxygen atoms. The ligand thqtcn(3-) sensitizes efficiently the near-infrared emission of Er, Nd (0.10% Qy), and Yb (0.60% Qy). For the first time, the effect of ligand protonation on the efficiency of the solid-state luminescence emission of lanthanides complexes is demonstrated by the decrease of the luminescence quantum yield observed for [Yb(H(1.5)thqtcn)](2)(OTf)(3) (0.26%) with respect to [Yb(thqtcn)] (0.60%). The water-soluble H(3)thqtcn-SO3 analogue of H(3)thqtcn and its lanthanide complexes has been prepared. The solution quantum yields of the thqtcn-SO33- complexes were measured in water at pH 7.4 (0.016% for Nd-III and 0.14% for Yb-III) and in deuterated water (Nd, 0.047%; Yb, 0.55%), and they are among the highest reported in the literature for Yb-III in aqueous solutions. The high thermodynamic and kinetic stability in water at physiological pH of the gadolinium complex of thqtcn-SO33- indicate that the lanthanide complexes of thqtcn(3-) and thqtcn-SO33- are highly resistant to hydrolysis and therefore are well suited for the development of luminescent devices and for application as probes in biomedical imaging.