Pushing the ligand field to the limit – Cyclometalated complexes of d8-configured metal ions as efficient triplet emitters

将配体场推向极限 d8 配置金属离子的环金属化配合物作为高效的三线态发射体

• 批准号: 403722766
• 负责人: Professor Dr. Nikos L. Doltsinis
• 金额: --
• 依托单位: Institut für Anorganische Chemie
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/403722766?language=en
• 关键词: Pushing; ligand; field; limit; Cyclometalated

The availability of cheap and efficient luminescent organometallic complexes is crucial for the development of photocatalysts, photovoltaic devices and organic light-emitting diodes (OLEDs). To date, most commercial applications rely on Ru(II), Os(II) or Ir(III) complexes, but Pt(II) and Au(III) complexes have shown to be interesting alternatives. This project aims to shift from these established complexes to other d8-configured derivatives. It is clear that Ag(III), Pd(II) and Ni(II) complexes are challenging, particularly in view of the reduced spin-orbit coupling and lower ligand-field splitting. However, they constitute appealing candidates for diverse applications considering the markedly higher abundance and lower price of Ni or Ag. Hence, we will implement tailored tri- and tetradentate ligands as chelating luminophoric units with 0, 1, 2 or 3 negative charges and cyclometalation sites to enhance the ligand field splitting while avoiding population of dissociative metal-centred states. d8-complexes with tridentate ligands offer the advantage of one open coordination flank that is available for the insertion of an ancillary ligand to complete the square-planar environment; they fine-tune absorption and emission energies and particularly the photoluminescence quantum yields by further enhancing the ligand field strength to slow down radiationless deactivation rates. A fundamentally new concept proposed herein will involve exploitation of heavy-element-based σ-donors as ancillary ligands of the type –E(aryl)3 (E = Ge, Sn or Pb) or Pn(aryl)3 (Pn = Sb, As, or Bi): This will allow us to enhance the spin-orbit coupling required if lighter (cheaper) metal centres are used, in order to boost radiative pathways. In this context, we will also study the potential of thermally-activated delayed fluorescence (TADF) processes relying on the lighter metals. We will combine a uniquely synergetic approach involving our complementary expertise fields spanning from electrochemical characterisation, steady-state and time-resolved photoluminescence spectroscopies (PL, from 6 to 380 K), to organometallic synthesis guided by in silico design and sophisticated (TD)DFT calculations addressing excited state dynamics. Hence, we will assess the character of the excited states and the involved transitions, while ab initio calculations will give predictive guidelines for the rational design of new organometallic coordination compounds. The already productive cooperation consolidated within the first funding period will be expanded and includes chemical synthesis of organometallic complexes (Strassert + Klein), photophysics and spectroscopy (Strassert), (spectro)electrochemistry (Klein), quantum-chemical simulations (Doltsinis) as well as ongoing and new collaborations with further partners within the SPP.

廉价、高效的发光金属有机配合物的获得对于光催化剂、光伏器件和有机发光二极管（OLED）的发展至关重要。迄今为止，大多数商业应用依赖于Ru（II）、Os（II）或Ir（III）络合物，但Pt（II）和Au（III）络合物已被证明是令人感兴趣的替代物。该项目旨在从这些已建立的复合物转移到其他d8构型的衍生物。显然，Ag（III）、Pd（II）和Ni（II）络合物是具有挑战性的，特别是考虑到降低的自旋-轨道耦合和较低的配体-场分裂。然而，考虑到Ni或Ag的显著更高丰度和更低价格，它们构成了各种应用的有吸引力的候选者。因此，我们将实施定制的三齿和四齿配体作为具有0、1、2或3个负电荷和环化位点的螯合发光单元，以增强配体场分裂，同时避免解离金属中心态的种群。具有三齿配体的D8-络合物提供了一个开放配位侧翼的优点，其可用于插入辅助配体以完成正方形平面环境;它们通过进一步增强配体场强度以减慢无辐射失活速率来微调吸收和发射能量，特别是光致发光量子产率。本文提出的一个全新概念将涉及利用基于重元素的σ-供体作为-E（芳基）3（E = Ge、Sn或Pb）或Pn（芳基）3（Pn = Sb、As或Bi）类型的辅助配体：这将允许我们增强如果使用较轻（较便宜）金属中心所需的自旋-轨道耦合，以促进辐射途径。在这方面，我们还将研究依赖于较轻金属的热激活延迟荧光（TADF）过程的潜力。我们将结合联合收割机独特的协同方法，涉及我们互补的专业知识领域，从电化学表征，稳态和时间分辨光致发光光谱（PL，从6到380 K），到有机金属合成，通过计算机设计和复杂的（TD）DFT计算解决激发态动力学。因此，我们将评估的激发态和所涉及的过渡的字符，而从头计算将给出合理的设计新的有机金属配位化合物的预测准则。在第一个供资期内巩固的已经富有成效的合作将得到扩大，包括有机金属络合物的化学合成（Strassert + Klein），电子物理学和光谱学（Strassert），（光谱）电化学（Klein），量子化学模拟（Doltsinis）以及与SPP内其他合作伙伴正在进行的和新的合作。