Tuning of the excitation wavelength from UV to visible region in Eu3+-β-diketonate complexes: Comparison of theoretical and experimental photophysical properties
作者:V. Divya、Ricardo O. Freire、M. L. P. Reddy
DOI:10.1039/c0dt01652g
日期:——
A novel class of efficient visible light sensitized antenna complexes of Eu3+ based on the use of a series of highly conjugated β-diketonates, namely, 1-(1-phenyl)-3-(2-fluoryl) propanedione, 1-(2-naphthyl)-3-(2-fluoryl)propanedione, 1-(4-biphenyl)-3-(2-fluoryl) propanedione, and 2,2â²-bis(di-p-tolylphosphino)-1,1â²-binaphthyl oxide as an ancillary ligand has been designed, synthesized, characterized and their photophysical properties investigated. The coordination geometries of the typical Eu3+ complexes were calculated using the Sparkle/PM3 model. Photophysical properties of europium complexes benefit from adequate protection of the metal by the rigid phosphine oxide ligand against non-radiative deactivation and efficient ligand-to-metal energy transfer exceeding 50% as compared to precursor samples. The replacement of the phenyl group with the naphthyl or biphenyl groups in the 3-position of the fluoryl based β-diketonate ligand remarkably extends the excitation window of the corresponding Eu3+ complexes towards the visible region (up to 500 nm). The highly conjugated β-diketonate ligands sensitize efficiently the luminescence of Eu3+ ions with quantum yields ranging from 19 to 43 % in the solid state, which is among the highest reported for a visible sensitized Eu3+complex. The theoretical quantum efficiencies from the Sparkle/PM3 structures are in good agreement with the experimental values, clearly attesting to the efficacy of the theoretical models.
设计、合成、表征了一系列高效可见光敏化Eu3+天线络合物,并研究了它们的物理光性质。这些新型络合物基于一系列高度共轭的β-二酮酸,即1-(1-苯基)-3-(2-氟基)丙二酮、1-(2-萘基)-3-(2-氟基)丙二酮、1-(4-联苯基)-3-(2-氟基)丙二酮,以及作为辅助配体的2,2â²-双(二对甲苯基膦)-1,1â²-联萘氧化物。使用Sparkle/PM3模型计算了典型Eu3+络合物的配位几何结构。与前体样品相比,刚性膦氧化物配体对金属的充分保护使铕络合物的光物理性质受益匪浅,非辐射失活和有效的配体-金属能量转移超过50%。在基于氟基的β-二酮酸配体的3位上用萘基或联苯基取代苯基,显著扩展了相应Eu3+络合物的激发窗口,使其朝向可见光区域(高达500 nm)。高度共轭的β-二酮酸配体可有效提高Eu3+离子的发光量子产率,在固态下为19%至43%,这是已报道的