Cuprophilic Interactions in Highly Luminescent Dicopper(i)–nhc–picolyl Complexes – Fast Phosphorescence or Tadf? † Chemcomm Communication View Article Online
Cuprophilic Interactions in Highly Luminescent Dicopper(i)–nhc–picolyl Complexes – Fast Phosphorescence or Tadf? † Chemcomm Communication View Article Online
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通讯作者：
Jö Rn Nitsch;F. Cisnetti;Andreas Steffen
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作者：
Jö Rn Nitsch;F. Cisnetti;Andreas Steffen
a本研究对一系列单体、二聚体和聚合的氯化铜-甲基吡啶配合物进行了研究，结果表明，亲铜相互作用可以确保强自旋轨道耦合，实现快速（反向）系统间穿越t1 - s2和t1 - s1，因此可以作为构建高效的基于Cu - I的TADF或t1发射体的设计基序。显示热激活延迟荧光（TADF）的发光分子，即热诱导反向系统间交叉（RISC） t1 - s1，随后从单线态s1 - s0发射，已被证明是特别适合oled和其他光子应用的材料，因为它们能够绕过自旋禁止的t1 - s0磷光。在这方面，具有d10结构的Cu I配合物在过去5年中获得了很多关注，因为缺乏金属中心的d - d*跃迁，导致非辐射衰变，结合TADF使它们与基于Ir iii和Pt ii的发射器具有竞争力。4-16虽然已经建立了一些结构-性能关系，17-19铜配合物中的TADF仍然难以先验预测，更不用说设计TADF材料了，因为它是一种激发态性质。相比之下，亲铜相互作用可以通过仔细选择配体环境而预先安排在基态，并且它们已被证明允许（尽管效率低）在简单的双核Cu I配合物中与桥接二膦和其他系统，20-23以及簇中发出磷光。24-26一些具有短Cu-Cu接触的diccopper (I)配合物（o2.8 Å）已被报道能通过TADF有效发射，但亲铜相互作用对这些配合物的影响尚未得到解决。通过对一类新型双齿铜(I) nhc -吡啶配合物的案例研究，我们发现亲铜相互作用可以通过增加自旋-轨道耦合（SOC）来极大地提高t1态的辐射速率常数，使其发射寿命与TADF相当，甚至可以参与TADF存在时的发光机制。因此，亲铜相互作用为高效的Cu I发射器提供了一种设计方法。在这项研究中，我们以氨水溶液中的氯化氮为基础和铜络合介质，通过简单的一步无银工艺制备了一系列Cu I nhc -吡啶配合物（1 - 7，图1）。30氮盐包括新的吡啶连接物，在图1中被功能化。
a This case study on a series of monomeric, dimeric and polymeric Cu I chlorido NHC–picolyl complexes shows that cuprophilic interactions can ensure strong spin–orbit coupling for fast (reverse)inter-system-crossing T 1 2 S 1 and T 1-S 0 , and therefore can serve as a design motif for the construction of highly efficient Cu I-based TADF or T 1 emitters. Luminescent molecules showing thermally activated delayed fluorescence (TADF), i.e. thermally induced reverse intersystem-crossing (RISC) T 1-S 1 with subsequent emission from the singlet excited state S 1-S 0 , have proven to be particularly suitable materials for OLEDs and other photonic applications, as they are able to bypass the spin-forbidden phosphorescence T 1-S 0. 1–3 In this regard, Cu I complexes with a d 10 configuration have gained a lot of attention in the last 5 years, as the absence of metal centred d–d* transitions, leading to non-radiative decay, in combination with TADF makes them competitive to Ir III-and Pt II-based emitters. 4–16 Although some structure–property relationships have been formulated, 17–19 TADF in copper complexes is still difficult to predict a priori, let alone to design TADF materials, as it is an excited state property. In contrast, cuprophilic interactions can be prearranged in the ground state by careful choice of the ligand environment, and they have been shown to allow, albeit inefficiently , phosphorescence in simple dinuclear Cu I complexes with bridging diphosphines and other systems, 20–23 and also in clusters. 24–26 A few dicopper(I) complexes with short Cu–Cu contacts (o2.8 Å) have been reported to emit efficiently via TADF, but the influence of cuprophilic interactions in those has yet not been addressed. In this case study on a family of new bidentate copper(I) NHC–picolyl complexes we show that cuprophilic interactions can greatly enhance the radiative rate constants of the T 1 state by increasing spin–orbit coupling (SOC), giving emission lifetimes comparable to TADF, and can even be involved in the luminescence mechanisms when TADF is present. Thus, cupro-philic interactions provide a design methodology for highly efficient Cu I emitters. For this study, we have prepared a series of Cu I NHC–picolyl complexes (1–7, Fig. 1) by a facile one-step silver-free procedure from azolium chlorides in aqueous ammonia as basic and copper complexing medium (see ESI †). 30 The azolium salts include new picolyl linkers, functionalized in the para position Fig. 1 Chemical structures of complexes 1–7, for dimers representative …