Centre de Biophysique Moléculaire, CNRS UPR 4301, 45071 Orléans Cedex 2, France.
Methods Appl Fluoresc. 2017 Jan 18;5(1):014002. doi: 10.1088/2050-6120/5/1/014002.
Recently, a strong interest has been directed towards near-infrared (NIR) emitting lanthanide(III) compounds as they do possess complementary advantages in respect to organic molecules and semi-conductor nanocrystals, especially in the fields of biological analysis and imaging. To benefit from their emission, a key requirement to fulfill is the sensitization of lanthanide(III) cations with an appropriate chromophore. This condition is especially challenging to address for the lanthanide(III) cations emitting in the NIR. The quest for new chromophores well adapted to the NIR-emitting lanthanide(III) ions is an important direction of research in order to broaden the rationalization of the parameters that control the sensitization process. In this work, we have investigated the ability of a readily available chromophoric ligand, the nalidixic acid, to sensitize lanthanide(III) cations with a specific interest for those emitting in the NIR. We have therefore performed an extensive study of the luminescence properties of lanthanide(III) complexes emitting in the visible and in the NIR ranges formed in situ upon mixing the corresponding Ln(III) nitrates (Ln(III) = Pr, Nd, Sm, Eu, Tb, Dy, Ho, Tm, Yb) with nalidixic acid (HNA) in a 1:3 molar ratio in the presence of a base. Luminescence spectra, quantum yields and luminescence lifetimes have been measured and discussed. The red emission of Eu with a quantum yield value of 5.90(3)%, red and NIR of Pr (7(1) · 10 and 5.6(1) · 10%) and Ho (9.3(2) · 10 and 2.8(1) · 10%), green of Tb (5.21(5)%), yellow and NIR of Dy (0.51(2) and 0.065(4)%), orange and NIR of Sm (0.147(5) and 0.037(2)%), as well as NIR of Nd (0.0321(2)%) and Yb (0.021(1)%) were observed. These results and analysis show that the nalidixate is a versatile chromophoric ligand that is suitable for the sensitization of nine different lanthanide(III) cations, five of them emitting in the NIR.
最近，人们对近红外（NIR）发射镧系（III）化合物产生了浓厚的兴趣，因为它们在生物分析和成像等领域确实具有与有机分子和半导体纳米晶体互补的优势。为了利用它们的发射，一个关键的要求是用适当的生色团敏化镧系（III）阳离子。对于发射近红外光的镧系（III）阳离子，满足这一条件尤其具有挑战性。寻找新的生色团，使其与发射近红外光的镧系（III）离子相适应，是拓宽控制敏化过程参数合理化的一个重要研究方向。在这项工作中，我们研究了一种现成的生色团配体——nalidixic 酸，它对发射近红外光的镧系（III）阳离子的敏化能力，特别关注发射近红外光的镧系（III）阳离子。因此，我们在碱的存在下，将相应的Ln(III)硝酸盐（Ln(III)=Pr、Nd、Sm、Eu、Tb、Dy、Ho、Tm、Yb）与nalidixic 酸（HNA）以 1:3 的摩尔比混合，原位形成了镧系（III）配合物，研究了其可见和近红外范围内的发光性质。测量并讨论了荧光光谱、量子产率和荧光寿命。Eu 发出红色荧光，量子产率为 5.90(3)%，Pr 发出红色和近红外光，量子产率分别为 7(1)·10 和 5.6(1)·10%，Ho 发出红色和近红外光，量子产率分别为 9.3(2)·10 和 2.8(1)·10%，Tb 发出绿色荧光，量子产率为 5.21(5)%，Dy 发出黄色和近红外光，量子产率分别为 0.51(2)和 0.065(4)%，Sm 发出橙色和近红外光，量子产率分别为 0.147(5)和 0.037(2)%，Nd 发出近红外光，量子产率为 0.0321(2)%，Yb 发出近红外光，量子产率为 0.021(1)%。这些结果和分析表明，nalidixate 是一种多功能的生色团配体，适合敏化九种不同的镧系（III）阳离子，其中五种发射近红外光。
