Carbostyrils are among the most widely used sensitising antennae for luminescentlanthanides; they afford bright complexes with Eu and Tb, and can also sensitise the emissions of the less commonly used Sm, Dy, Yb and Nd. Systematic studies on the effect of structural variations on the photophysical properties and lanthanide sensitising abilities of carbostyrils can therefore have a large impact. We
Electron transfer pathways in photoexcited lanthanide(<scp>iii</scp>) complexes of picolinate ligands
作者:Daniel Kovacs、Daniel Kocsi、Jordann A. L. Wells、Salauat R. Kiraev、K. Eszter Borbas
DOI:10.1039/d1dt00616a
日期:——
Eu(III), however, quantum yields were lower than in other octadentate complexes lacking pyridylcarboxylate. Complexes with more electron-poor pyridines were less emissive even when equipped with the same antenna. The oxidation and reduction potentials of the antennae and the pyridinecarboxylates, respectively, were determined by cyclic voltammetry. The obtained values were consistent with electron transfer
合成了由1,4,7-三氮杂环壬烷骨架和三个仲酰胺连接的羧甲基苯乙烯触角组成的一系列发光镧系元素(III)配合物。金属结合位点用两个吡啶基羧酸酯供体增加,产生八齿配体。该天线在其4位上带有甲基,甲氧基甲基或三氟甲基取代基,从而具有一定范围的激发态能量和天线电子特性。Eu(III)的1 H NMR光谱)发现复合物彼此相似。通过单晶X射线晶体学在固态中获得了相似的结果,该结果表明该结构具有九个配位的金属离子,具有严重扭曲的三键三角棱镜几何形状。稳态和时间分辨发光光谱表明,触角可同时激发Tb(III)和Eu(III)),但是,量子产率低于缺少吡啶基羧酸盐的其他八齿络合物。即使配备相同的天线,具有更多电子贫乏吡啶的配合物的发射率也较低。通过循环伏安法分别测定触角和吡啶羧酸盐的氧化和还原电位。所获得的值与电子从受激天线向吡啶的转移相一致,从而提供了以前无法探索的淬灭途径,可以有效地与向镧系元素的能量转
Reduced quenching effect of pyridine ligands in highly luminescent Ln(<scp>iii</scp>) complexes: the role of tertiary amide linkers
作者:Daniel Kocsi、Daniel Kovacs、Jordann A. L. Wells、K. Eszter Borbas
DOI:10.1039/d1dt02893f
日期:——
two bidentate picolinate donors. Antennae were connected to the metal binding site via tertiary amidelinkers. Antennae and donors were assembled on a 1,4,7-triazacyclononane (tacn) platform. Solution- and solid-state structures were comparable to those of previously reported complexes with tacn architectures, with nine-coordinate distorted tricapped trigonal prismatic Ln(III) centres, and distinct from
发光的 Eu( III ) 和 Tb( III ) 配合物是由携带各种喹诺酮致敏天线和两个双齿吡啶甲酸酯供体的八齿配体合成的。天线通过叔酰胺接头连接到金属结合位点。天线和供体组装在 1,4,7-三氮杂环壬烷 (tacn) 平台上。溶液和固态结构与先前报道的具有 tacn 结构的配合物相当,具有九坐标扭曲的三棱柱棱柱 Ln( III) 中心,与基于 1,4,7,10-四氮杂环十二烷 (cyclen) 大环的中心不同。相比之下,这些基于叔酰胺 tacn 的配合物的光物理性质与先前报道的具有环烯配体的系统相比更具可比性,显示出高效的 Eu( III ) 和 Tb( III ) 发光。这代表了对二级酰胺连接的类似物的改进,并且是由于在三级酰胺连接的复合物中大大提高了敏化效率。由于抑制了光致电子转移和反向能量转移,叔酰胺连接的 Eu( III ) 和 Tb( III ) 发射体比其二级酰胺连接的类似物更耐光。
Photophysics of Coumarin and Carbostyril-Sensitized Luminescent Lanthanide Complexes: Implications for Complex Design in Multiplex Detection
作者:Daniel Kovacs、Xi Lu、Lívia S. Mészáros、Marjam Ott、Julien Andres、K. Eszter Borbas
DOI:10.1021/jacs.6b11274
日期:2017.4.26
Luminescent lanthanide (Ln(III)) complexes with coumarin or carbostyril antennae were synthesized and their photophysical properties evaluated using steady-state and time-resolved UV-vis spectroscopy. Ligands bearing distant hydroxycoumarin-derived antennae attached through triazole linkers were modest sensitizers for Eu(III) and Tb(III), whereas ligands with 7-amidocarbostyrils directly linked to the coordination site could reach good quantum yields for multiple Ln(III), including the visible emitters Sm(III) and Dy(III), and the near-infrared emitters Nd(III) and Yb(III). The highest lanthanide-centered luminescence quantum yields were 35% (Tb), 7.9% (Eu), 0.67% (Dy), and 0.18% (Sm). Antennae providing similar luminescence intensities with 2-4 Ln-emitters were identified. Photoredox quenching of the carbostyril antenna excited states was observed for all Eu(III)-complexes and should be sensitizing in the case of Yb(III); the scope of the process extends to Ln(III) for which it has not been seen previously, specifically Dy(III) and Sm(III). The proposed process is supported by photophysical and electrochemical data. A FRET-type mechanism was identified in architectures with both distant and close antennae for all of the Lns. This mechanism seems to be the only sensitizing one at long distance and probably contributes to the sensitization at shorter distances along with the triplet pathway. The complexes were nontoxic to either bacterial or mammalian cells. Complexes of an ester-functionalized ligand were taken up by bacteria in a concentration-dependent manner. Our results suggest that the effects of FRET and photoredox quenching should be taken into consideration when designing luminescent Ln complexes. These results also establish these Ln(III)-complexes for multiplex detection beyond the available two-color systems.
Coordination Environment-Controlled Photoinduced Electron Transfer Quenching in Luminescent Europium Complexes
作者:Daniel Kovacs、Emilie Mathieu、Salauat R. Kiraev、Jordann A. L. Wells、Ellen Demeyere、Agnès Sipos、K. Eszter Borbas
DOI:10.1021/jacs.0c05518
日期:2020.7.29
ns and ms timescales. The contribution of photoinduced electron transfer to the overall reduction of the Eu(III) luminescence quantum yield was found to be comparable, and in many cases, larger than the quenching caused by well-established processes such as coupling to X-H oscillators. These results suggest that the elimination or mitigation of photoinduced electron transfer could substantially improve
研究了通过光诱导电子从激发的光捕获天线到 Eu(III) 的转移对敏化 Eu(III) 发光的猝灭。制备了一系列包含不同金属结合位点并因此具有不同 Eu(III)/Eu(II) 还原电位的配合物。使用单晶 X 射线晶体学和顺磁 1 H NMR 光谱的组合对配合物进行了充分表征,其结果支持配合物的结构相似性。使用循环伏安法以及 ns 和 ms 时间尺度上的稳态和时间分辨发射光谱研究了 Eu(III) 中心和光捕获天线的氧化还原和光物理行为。发现光致电子转移对 Eu(III) 发光量子产率的整体降低的贡献是可比的,并且在许多情况下,大于由成熟过程(例如与 XH 振荡器耦合)引起的猝灭。这些结果表明,消除或减轻光致电子转移可以显着改善广泛使用的 Eu(III) 基发射器的发射特性。