Sterically hindered phenanthroimidazole ligands drive the structural flexibility and facile ligand exchange in cyclometalated iridium(<scp>iii</scp>) complexes
作者:Sergei V. Tatarin、Paulina Kalle、Ilya V. Taydakov、Evgenia A. Varaksina、Vladislav M. Korshunov、Stanislav I. Bezzubov
DOI:10.1039/d1dt00820j
日期:——
Though the enhanced reactivity of the complexes is contrary to the common idea of the high inertness of iridium(III) compounds it can be seen as a consequence of the interplay between the steric hindrance induced by the ligands and the strong preference of the iridium(III) ion for octahedral geometry. This study demonstrates that the use of bulky ligands provides access to light-harvesting iridium(III) complexes
We present the elegant synthesis and the photophysical and electroluminescent properties of a series of cyclometalatediridium(III) complexes [Ir(PPI)2(pic), PPI: 1,2‐diphenyl‐1H‐phenanthro[9,10‐d]imidazole; pic: picolinic acid]. The Ir(PPI)2(pic) complexes showed characteristic phosphorescence with an emission range of 556–579 nm and a high quantum efficiency with microsecond lifetimes. The strongly
fluoro substituent as an electron acceptor fragment in the fluorescent chargetransfer (CT) states has been investigated. The mechanism of the radiativecharge recombination CT → S0 is discussed in terms of the Mulliken–Murrell model of the CT complexes and the Marcus theory of photoinduced electron transfer (ET). Solvatochromic effects on the spectral position and profile of the stationary fluorescence
已经研究了包含氟取代基的菲咪唑衍生物的所选供体 (D) 受体 (A) 衍生物的溶剂依赖性电子结构,作为荧光电荷转移 (CT) 状态中的电子受体片段。辐射电荷复合的机理 CT → S 0根据 CT 复合物的 Mulliken-Murrell 模型和光致电子转移 (ET) 的 Marcus 理论进行讨论。对固定荧光光谱的光谱位置和轮廓的溶剂致变色效应清楚地表明在极性和非极性环境中研究的所有化合物的发射单线态的 CT 特征。CT 荧光分析得出与 Marcus 倒置区域中的电子转移相关的数量。荧光速率常数 ( k r ) 和相应跃迁偶极矩 ( M ) 的值及其溶剂极性依赖性表明发射1 CT 态和基态是辐射跃迁的控制因素。相对较大的M值表明在荧光状态下供体和受体亚基的非正交几何形状。结果表明,在可以忽略系统间跨越激发三重态的情况下,Marcus 理论可用于定量描述无辐射电荷复合过程。