含区位异构氨基萘酰亚胺配体的环Ir配合物三重态光敏剂的合成、光物理性质以及在三重态湮灭上转换中的应用

Preparation of cyclometalated Ir(Ⅲ) complexes triplet photosensitizers containing regioisomeric ethylaminonaphthalimide ligands-photophysical properties and application in triplet-triplet annihilation upconversion

以区位异构化的氨基萘酰亚胺(NI)为吸光基团,通过炔键将2个NI区位异构体分别连接到2,2′-联吡啶配体上,制备了2个环Ir(III)配合物.利用稳态吸收与发光光谱、瞬态吸收与发光光谱,并结合理论化学计算,对配合物的光物理性质进行了研究.与已报道的同类Ir(III)配合物相比,新配合物的可见光吸收能力得到了增强(如在504 nm处摩尔吸光系数达到12000 L mol?1 cm?1),三重激发态寿命得到了延长(达到24.1?s,传统Ir配合物的三重态寿命一般短于5.0?s).此外,纳秒时间分辨瞬态吸收谱以及自旋密度的DFT计算表明,配合物的T1激发态具有明显的配体激发态的特征(3IL激发态),而不是传统Ir(III)配合物的金属到配体的电荷转移激发态(3MLCT激发态).由于新Ir(III)配合物具有强可见光吸收、长寿命三重激发态,所以配合物表现出了较强的三重态湮灭上转换能力.研究结果表明,引入合适的有机吸光配体,采用与配位中心共轭连接的分子结构设计模式,可有效增强配合物的可见光吸收能力,延长三重激发态的寿命;同时,具有区位异构有机吸光基团的Ir(III)配合物,表现出很大差异的光物理性质.本文的研究将有助于制备具有可见光吸收能力的Ir(III)配合物,以及研究有机吸光基团三重激发态.

Visible light-harvesting cyclometalated Ir（Ⅲ） complexes showing long-lived triplet excited states were prepared with regioisomeric aminonaphthaleneimide ligands. The photophysical properties of the complexes were studied with steady state and time-resolved spectroscopies, as well as DFT calculation. Compared to the known cyclometalated Ir（Ⅲ） complexes, the new complexes show ligand-localized triplet excited state （3IL state）, instead of the normal 3MLCT state. The two complexes with regioisomeric NI ligands show drastically different photophysical properties, such as phosphorescence quantum yields. The complexes were used as triplet photosensitizer for triplet-triplet annihilation （TTA） upconversion. TTA upconversion quantum yield up to 19.3% was observed. These results are useful for preparation of visible light-harvesting Ir（Ⅲ） complexes and for the study of the triplet excited state of organic chromophores.