Univ. Grenoble Alpes, CNRS, DCM, 38000, Grenoble, France.
Institute for Advanced Biosciences, INSERM U1209, UMR CNRS 5309, Grenoble Alpes University, 38700, La Tronche, France.
Chem Asian J. 2022 Sep 1;17(17):e202200544. doi: 10.1002/asia.202200544. Epub 2022 Jul 28.
Three lanthanide complexes (Ln=Gd, Eu) based on a DO3 A ([Ln(L )]) or DO2 A ([Ln(L )] ) platform appended by a redox active TEMPO-based arm were prepared. Complex [Ln(L )] shows an alkyne arm, offering the possibility of postfunctionalization by click reaction to yield [Ln(L )] . The complexes demonstrate a redox response whereby the hydroxylamine, nitroxide and oxoammonium forms of the arm can be obtained in turn. Luminescence measurements on the europium complexes support an octadentate (L , L ) or heptadentate (L ) chelation by the ligand, with one water molecule in the inner coordination sphere. The relaxivity was determined from 20 kHz to 30 MHz by fast-field cycling NMR. The three Gd complexes under their hydroxylamine form [Gd(L )] and [Gd(L )] show r values of 7.0, 5.1 and 5.0 mM s (30 KHz), which increase to 8.8, 5.5 and 6.1 mM s in the nitroxide form. The radical complexes are not toxic against M21 cell lines, at least up to 40 μM. By using EPR spectroscopy we establish that they do not penetrate the cells with the exception of [Eu(L )] .
基于 DO3A([Ln(L)])或 DO2A([Ln(L)])平台的三种镧系元素配合物（Ln=Gd，Eu），通过一个氧化还原活性的 TEMPO 臂进行了修饰。配合物[Ln(L)]具有炔基臂，通过点击反应进行后功能化，生成[Ln(L)]。这些配合物具有氧化还原响应，通过该响应可以依次得到臂的羟胺、氮氧自由基和氧代铵形式。对铕配合物的发光测量表明，配体通过螯合作用形成了八配位（L,L）或七配位（L），内配位球中有一个水分子。通过快速场循环 NMR 从 20 kHz 到 30 MHz 确定了弛豫率。三种处于羟胺形式的 Gd 配合物[Gd(L)]、[Gd(L)]和[Gd(L)]的 r 值分别为 7.0、5.1 和 5.0 mM s（30 kHz），在氮氧自由基形式下增加到 8.8、5.5 和 6.1 mM s。自由基配合物对 M21 细胞系没有毒性，至少在 40 μM 以下没有毒性。通过使用 EPR 光谱，我们确定除[Eu(L)]外，它们不会穿透细胞。
