Two new bis(dipivaloylmethanate)nitrato-bis(triphenylphosphine oxide)lanthanide(III) complexes [Eu(dpm)2(NO3)(tppo)2] (1) and [Tb(dpm)2(NO3)(tppo)2] have been prepared in monomeric form. The structural behavior of these coordination compounds is significantly different from those of [Eu2(dpm)6] and [Tb2(dpm)6] dimeric complexes. The photoluminescent properties of the monomeric and dimeric complexes are dependent on the energy positions of the low-lying ligand-to-metal charge-transfer (LMCT) state, which may be correlated with the chelating and chelate bridging coordination modes of the dpm ligand, respectively. The monomeric complex presents higher luminescence intensity than the dimeric complex due to the higher energy of the LMCT state in this system. Although the excited energy levels of the EuIII ion in complex 1 undergo efficient depopulation by LMCT, the same is not observed for the 5D0 emitting level, which presents values of the emitting lifetime that are almost temperature independent. The triboluminescence phenomenon of the [Ln(dpm)2(NO3)(tppo)2] complex is also discussed.

中文翻译：

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配体到金属电荷转移状态在二新戊酰基甲烷酸酯-镧系元素分子内能量转移过程中的作用

两种新的双(二新戊酰甲烷酸酯)硝基-双(三苯基氧化膦)镧系元素(III)配合物[Eu(dpm)2(NO3)(tppo)2](1)和[Tb(dpm)2(NO3)(tppo)2]已制备成单体形式。这些配位化合物的结构行为与[Eu2(dpm)6]和[Tb2(dpm)6]二聚复合物的结构行为明显不同。单体和二聚体配合物的光致发光特性取决于低位配体到金属电荷转移 (LMCT) 状态的能量位置，这可能与 dpm 配体的螯合和螯合桥连配位模式相关，分别。由于该系统中 LMCT 状态的能量较高，单体复合物呈现出比二聚复合物更高的发光强度。尽管复合物 1 中 EuIII 离子的激发能级通过 LMCT 进行了有效的减少，但对于 5D0 发射级却没有观察到相同的情况，其呈现的发射寿命值几乎与温度无关。还讨论了[Ln(dpm)2(NO3)(tppo)2]配合物的摩擦发光现象。