New Ir(III) complexes involving N,C-chelating difluorophenyl-pyridine (dfppy) or dibenzo[a,c]phenazine (dbpz) ligands along with either N,N-bound 5-ethynyl-2,2′-bipyridine (e-bpy) or CO + Cl co-ligands have been obtained as [Ir(dfppy)2(e-bpy)]PF6, [Ir(dbpz)2(e-bpy)]PF6 and cis-[Ir(dbpz)2(Cl)(CO)]. A single-crystal X-ray diffraction study of cis-[Ir(dbpz)2(CO)Cl] has shown the Ir(III) centre to adopt a distorted octahedral coordination geometry with cis-CO/Cl and trans-N,N configurations. Pronounced π–π stacking interactions involving different dibenzo[a,c]phenazine units are evident. Electronic absorption and luminescence spectroscopy at 298 K and 77 K, along with cyclic voltammetry were used to study the three complexes. Excited state lifetimes varied from 1.4 to 2.9 μs at rt with quantum yields ranging from 10.2 to 0.7%. With 5-ethynyl-2,2′-bipyridine in the first coordination sphere, the lowest emitting state is that associated with the MLCT band, whereas in the bis-phenazine case the emission is ligand-centred. Importantly, the emission wavelength can be tuned from 552 to 640 nm by changing the conjugation length of the N,C ligand.
新型Ir(III)配合物包括N,C-螯合的二
氟苯基
吡啶(dfppy)或二苯并[a,c]苯并嗪(dbpz)
配体,以及N,N-配位的5-
乙炔基-2,2′-联
吡啶(e-bpy)或CO + Cl共
配体,分别得到[Ir(dfppy)2(e-bpy)]PF6、[Ir(dbpz)2(e-bpy)]PF6和顺式-[Ir(dbpz)2(Cl)(CO)]。顺式-[Ir(dbpz)2(CO)Cl]的单晶X射线衍射研究表明,Ir(III)中心采用扭曲的八面体配位几何,具有顺式的CO/Cl和反式的N,N配置。明显的π-π堆积相互作用体现在不同的二苯并[a,c]苯并嗪单元之间。在298 K和77 K下,通过电子吸收和发光光谱以及循环伏安法研究了这三种配合物。激发态寿命在室温下从1.4到2.9 μs变化,量子产率范围从10.2%到0.7%。在第一配位球中加入5-
乙炔基-2,2′-联
吡啶时,最低发射态与MLCT带相关,而在双苯并嗪情况下,发射则以
配体为中心。重要的是,通过改变N,C
配体的共轭长度,发射波长可以从552 nm调节到640 nm。