Molecular Ladders of Lanthanide-3-phenyl-4-benzoyl-5-isoxazolonate and Bis(2-(diphenylphosphino)phenyl) Ether Oxide Complexes: The Role of the Ancillary Ligand in the Sensitization of Eu3+ and Tb3+ Luminescence

Three new lanthanide heterocyclic β-diketonate complexes having the general formula Ln(PBI)3(DPEPO) [HPBI = 3-phenyl-4-benzoyl-5-isoxazolone, DPEPO = bis(2-(diphenylphosphino)phenyl) ether oxide and Ln3+ = Eu3+ (1), Tb3+ (2), and Gd3+ (3)] have been synthesized. Compounds 1 and 2 were characterized by single-crystal X-ray diffraction. The single-crystal X-ray diffraction analyses of 1 and 2 revealed that these complexes are mononuclear, and that the central Ln3+ ion is coordinated by six oxygen atoms furnished by three bidentate β-diketonate ligands and two oxygen atoms from the bidentate DPEPO ligand. The overall molecular geometry is distorted square prismatic. Examination of the packing diagrams for 1 and 2 revealed the presence of interesting molecular ladder structures held together by π···π and intermolecular hydrogen-bonding interactions. The effect of the chelating ancillary phosphine oxide ligand DPEPO on the sensitized luminescence of Eu3+ and Tb3+ luminescence in these heterocyclic β-diketonate complexes has been investigated. The ancillary ligand increases considerably the luminescence efficiency of [Eu(PBI)3(DPEPO)] (overall quantum yield 2−30%; 5D0 lifetime 250−1056 μs) compared to Eu(PBI)3(C2H5OH)(H2O), through the formation of intraligand states, while it is detrimental to Tb3+ luminescence in [Tb(PBI)3(DPEPO)] (overall quantum yield 11 to 0.5%; 5D4 lifetime 400 to 168 μs).

合成了一种通式为Ln(PBI)3(DPEPO)（其中HPBI为3-苯基-4-苯甲酰-5-异恶唑酮，DPEPO为双(2-(二苯基膦基)苯基)醚氧化物，Ln3+分别为Eu3+（1）、Tb3+（2）和Gd3+（3））的新型镧系元素杂环β-二酮酸络合物。化合物1和2通过单晶X射线衍射进行了表征。对1和2的单晶X射线衍射分析揭示了这些络合物为单核结构，中心Ln3+离子被三个双齿β-二酮酸配体提供的六个氧原子以及来自双齿DPEPO配体的两个氧原子配位。整体的分子几何构型为扭曲的四方棱柱形。对1和2的堆积图分析揭示了由π…π和分子间氢键相互作用维持的有趣分子梯状结构的存在。研究了辅助配位螯合膦氧化物DPEPO对这些杂环β-二酮酸络合物中Eu3+和Tb3+敏化发光的影响。辅助配体显著提高了[Eu(PBI)3(DPEPO)]（总量子产率2−30%；5D0寿命250−1056 μs）的发光效率，相较于Eu(PBI)3(C2H5OH)(H2O)，这是通过形成配体内态实现的，而对[Tb(PBI)3(DPEPO)]中的Tb3+发光（总量子产率11到0.5%；5D4寿命400到168 μs）则具有不利影响。