First examples of luminescent zinc(II)-bisquinoxalinato complexes: Synthesis, spectroscopic and theoretical studies
摘要:
Four novel homoleptic zinc(II) complexes were prepared in high yield from para-substituted 2,3-diphenyl-5-hydroxyquinoxaline ligands, LHn, giving [Zn(L-n)(2)]. Density functional theoretical calculations were performed to probe the influence of the variation in para-substitution on the ligands. The calculations suggest that ligand-centred character appears to dominate the HOMO and LUMOs. Experimental electro-chemical and spectroscopic characterisation showed that the subtle variations in absorption and emission wavelengths are due to ligand-dominated transitions that are influenced by electronic nature of the para-substituted phenyl units in coordinated L-n, in both solution and the solid states. (C) 2012 Elsevier B. V. All rights reserved.
New 2,3-disubstituted-5-hydroxyquinoxaline ligands and their coordination chemistry with cyclometallated iridium(iii): syntheses, structures and tunable electronic properties
摘要:
我们合成了一系列新的对位取代的 2,3-二苯基-5-羟基喹喔啉配体(LHn),并对其进行了表征。这些配体是通过两步合成法以高产率制备的。相应地,还制备出了四种新型杂色铱(III)配合物,并得到了高产率的[Ir(ppy)2(Ln)]。对 LH3 和[Ir(PY)2(L2)]进行了两次 X 射线晶体学研究,结果均证实了所提出的配方,其中络合物显示了喹喔啉配体的 O、N 配位模式。我们进行了密度泛函理论计算,首先是比较配位的喹喔啉配位体系和相关的喹啉配位类似物,其次是探究对位取代变化对辅助配体的影响。计算结果表明,无论是喹啉还是喹喔啉系统,配体中心特性似乎都主导着 HOMO 和 LUMO。实验电化学和光谱特性分析表明,吸收和发射波长的微妙变化可能是由于配体主导的转变,而配体主导的转变受到配位 Ln 中对位取代的苯基单元的电子性质的影响。