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首页> 外文期刊>Chemistry: A European journal >Cationic bis-cyclometallated iridium(III) phenanthroline complexes with pendant fluorenyl substituents: Synthesis, redox, photophysical properties and light-emitting cells
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Cationic bis-cyclometallated iridium(III) phenanthroline complexes with pendant fluorenyl substituents: Synthesis, redox, photophysical properties and light-emitting cells

机译：带有芴基侧基取代基的阳离子双环金属化铱（III）菲咯啉配合物：合成，氧化还原，光物理性质和发光电池

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摘要

We report the synthesis, characterisation, photophysical and electrochemical properties of a series of cationic cyclometallated Ir-III complexes of general formula [Ir(ppy)(2)(phen)]PF6 (ppy = 2-phenylpyridine, phen=a substituted phenanthroline). A feature of these complexes is that the phen ligands are substituted with one or two 9,9-dihexylfluorenyl substituents to provide extended pi conjugation, for example, the 3-[2-(9,9-dihexylfiuorenyl)]phenanthroline and 3,8-bis[2-(9,9-dihexylfluorenyl)]phenanthroline ligands afford complexes 6 and 9, respectively. A single-crystal X-ray diffraction study of a related complex 18 containing the 3,8-bis(4-iodophenyl)phenanthroline ligand, revealed an octahedral coordination of the Ir atom, in which the metallated C atoms of the ppy ligands occupy cis positions. The complexes 6 and 9 displayed reversible oxidation waves in cyclic voltammetric studies (E-1/2(ox)=+1.18 and +1.20V, respectively, versus Ag/Ag+ in CH2Cl2) assigned to the metal-centred Ir-III/Ir-IV couple. The complexes exhibit strong absorption in the UV region in solution spectra, due to spin-allowed ligand-centred (LC) (1)pi-pi* transitions; moderately intense bands occur at approximately 360-390nm which are red-shifted with increased ligand length. The photoluminescence spectra of all the complexes were characterised by a broad band at lambda(max)approximate to 595nm assigned to a combination of (MLCT)-M-3 and (3)pi ->pi* states. The long emission lifetimes (in the microsecond time-scale) are indicative of phosphorescence: the increased ligand conjugation length in complexes 9 and 17 leads to increased lifetimes for the complexes (tau=2.56 and 2.57 mu s in MeCN, respectively) compared to monofluorenyl analogues 6 and 15 (tau=1.43 and 1.39 mu s, respectively). DFT calculations of the geometries and electronic structures of complexes 6', 9' (for both singlet ground state (S-0) and triplet first excited (T-1) states) and 18 have been performed. In the singlet ground state (S-0) HOMO orbitals in the complexes are spread between the Ir atom and benzene rings of the phenylpyridine ligand, whereas the LUMO is mainly located on the phenanthroline ligand. Analysis of orbital localisations for the first excited (T-1) state have been performed and compared with spectroscopic data. Spin-coated light-emitting cells (LECs) have been fabricated with the device structures ITO/PEDOT:PSS/Ir complex/Al, or Ba capped with Al (ITO=indium tin oxide, PEDOT = poly(3,4-ethylenedioxythiophene), PSS = poly(styrene) sulfonate). A maximum brightness efficiency of 9 cd A(-1) has been attained at a bias of 9 V for 17 with a Ba/Al cathode. The devices operated in air with no reduction in efficiency after storage for one week in air.
机译：我们报告了一系列通式为[Ir（ppy）（2）（phen）] PF6（ppy = 2-苯基吡啶，phen = a取代的菲咯啉）的阳离子环金属化Ir-III配合物的合成，表征，光物理和电化学性质。这些配合物的特征在于，phen配体被一个或两个9,9-二己基芴基取代基取代以提供扩展的pi共轭作用，例如3- [2-（9,9-二己基氟烯基）]菲咯啉和3,8 -双[2-（9，9-二己基芴基）]菲咯啉配体分别提供配合物6和9。对包含3,8-双（4-碘苯基）菲咯啉配体的相关配合物18的单晶X射线衍射研究显示Ir原子具有八面体配位，其中ppy配体的金属化C原子占据了顺式职位。分配给以金属为中心的Ir-III / Ir的循环伏安研究中，配合物6和9显示出可逆的氧化波（分别为E-1 / 2（ox）= + 1.18和+ 1.20V，相对于CH2Cl2中的Ag / Ag +）。 -IV夫妇。由于自旋允许的以配体为中心的（LC）（1）pi-pi *跃迁，络合物在溶液光谱的UV区显示出强吸收性。中等强度的谱带出现在大约360-390nm处，随着配体长度的增加红移。所有复合物的光致发光光谱的特征是λ（max）约至595nm处的宽带，分配给（MLCT）-M-3和（3）pi-> pi *状态的组合。较长的发射寿命（以微秒为单位）表示磷光：与单芴基相比，配合物9和17中配体共轭长度的增加导致配合物的寿命增加（在MeCN中分别为tau = 2.56和2.57μs）。类似物6和15（tau分别为1.43和1.39μs）。已经对配合物6'，9'（对于单重态基态（S-0）和三重态第一激发态（T-1））和18的几何形状和电子结构进行了DFT计算。在单线基态（S-0）中，配合物中的HOMO轨道分布在苯基吡啶配体的Ir原子和苯环之间，而LUMO主要位于菲咯啉配体上。已对第一激发态（T-1）进行了轨道定位分析，并与光谱数据进行了比较。旋涂式发光单元（LEC）的制造具有ITO / PEDOT：PSS / Ir配合物/ Al或Ba覆盖Al的器件结构（ITO =氧化铟锡，PEDOT =聚（3,4-乙撑二氧噻吩） ，PSS =聚（苯乙烯）磺酸盐）。使用Ba / Al阴极在9 V的偏压下对于17可获得最大亮度9 cd A（-1）。在空气中存放一周后，设备在空气中运行不会降低效率。

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