Luminescent Eu(iii) complexes with point-chiral phosphine oxide ligands, [Eu(hfa)3((R,R)-B2QPO)] (hfa: hexafluoroacetylacetonato, B2QPO: 2,3-bis(tert-butylmethylphosphine oxide)quinoxaline) and [Eu(hfa)3((R)-B3QPO)] (B3QPO: 2-tert-butylmethylphosphine oxide-3-(di-tert-butylphosphineoxide)quinoxaline), are reported for the investigation of the electronic strain effect on the coordination sphere. Single crystal X-ray crystallography reveals the strong structural strain of the hfa ligands in [Eu(hfa)3((R,R)-B2QPO)]. The emission quantum yields of [Eu(hfa)3((R,R)-B2QPO)] in solution (55%) and solid (63%) are comparable to those of previously reported bright luminescent Eu(iii) complexes. The chiroptical properties of [Eu(hfa)3((R,R)-B2QPO)] and [Eu(hfa)3((R)-B3QPO)] were characterized using circular dichroism (CD) and circularly polarized luminescence (CPL) spectra. The dissymmetry factor of [Eu(hfa)3((R,R)-B2QPO)] was estimated to be 0.08. The chiroptical phenomena of the Eu(iii) complexes are closely related to their structural (geometry) and electronic (LMCT: ligand-to-metal charge transfer) strains.

中文翻译：

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电子应变效应对Eu（iii）配合物的圆极化发光增强。

具有点手性氧化膦配体[Eu（hfa）3（（R，R）-B2QPO）]的发光Eu（iii）配合物（hfa：六氟乙酰丙酮，B2QPO：2,3-双（叔丁基甲基氧化膦）喹喔啉）和[Eu（hfa）3（（R）-B3QPO）]（B3QPO：2-叔丁基甲基氧化膦-3-（二叔丁基氧化膦）喹喔啉）被报道用于研究电子应变对配位的影响领域。单晶X射线晶体学显示[Eu（hfa）3（（R，R）-B2QPO）]中hfa配体的强结构应变。溶液（55％）和固体（63％）中[Eu（hfa）3（（R，R）-B2QPO）]的发射量子产率与先前报道的明亮发光Eu（iii）配合物相当。[Eu（hfa）3（（R，R）-B2QPO）]和[Eu（hfa）3（（R）-B3QPO）]用圆二色性（CD）和圆偏振发光（CPL）光谱表征。[Eu（hfa）3（（R，R）-B2QPO）]的不对称因子估计为0.08。Eu（iii）配合物的手性现象与它们的结构（几何）应变和电子（LMCT：配体-金属电荷转移）应变密切相关。