Weber Michael D, Viciano-Chumillas Marta, Armentano Donatella, Cano Joan, Costa Rubén D
Department of Chemistry and Pharmacy, University of Erlangen-Nuremberg (FAU), Egerlandstr. 3, D-91058 Erlangen, Germany.
Dalton Trans. 2017 May 16;46(19):6312-6323. doi: 10.1039/c7dt00810d.
This work studies the effect of the σ-Hammett parameter (σ) - i.e., the σ-donation effect caused by substitution at the para position of a bipyridine ligand (4,4'-Rbipy, where R is MeO, Me, H, NO) - on both the photo- and electro-luminescence features of a series of heteroleptic copper(i) complexes - i.e., [Cu(N^N)(P^P)] where N^N and P^P ligands are Rbipy and Xantphos, respectively. By virtue of a comprehensive photophysical, theoretical, and thin-film lighting device - i.e., light-emitting electrochemical cells (LECs) - investigation, we note a clear relationship between the σ and the photo- and electro-luminescence parameters, such as photoluminescence quantum yields, excited-state lifetimes, and emission maxima, as well as device brightness, stability, and efficacy, respectively. As the most relevant finding, the substitution with the group featuring the most negative σ - i.e., MeO - provides a ca. five-fold enhancement of all of the aforementioned figures-of-merit upon comparison within the series of complexes. As such, this work provides a new guideline for a device optimization through a rational ligand design for heteroleptic copper(i) complexes.
本工作研究了σ-哈米特参数（σ）的影响，即联吡啶配体（4,4'-Rbipy，其中R为甲氧基、甲基、氢、硝基）对位取代引起的σ-给电子效应，对一系列异质配位铜（I）配合物，即[Cu（N^N）（P^P）]（其中N^N和P^P配体分别为Rbipy和Xantphos）的光致发光和电致发光特性的影响。通过全面的光物理、理论和薄膜照明器件（即发光电化学电池，LEC）研究，我们注意到σ与光致发光和电致发光参数之间存在明确的关系，分别如光致发光量子产率、激发态寿命和发射最大值，以及器件亮度、稳定性和效率。作为最相关的发现，与该系列配合物相比，用具有最负σ值的基团（即甲氧基）取代可使上述所有品质因数提高约五倍。因此，本工作通过对异质配位铜（I）配合物进行合理的配体设计，为器件优化提供了新的指导方针。
