新型三價銥金屬磷光錯合物的合成及其光物理的研究

Abstract

本篇論文的第一部份主要在敘述利用兩個 N-phenyl-substituted pyrazoles 和 2-pyridyl pyrazole (or triazole) ligands 來合成一系列室溫下具有高效率藍色磷光放光的銥金屬錯合物。利用 X-ray 單晶繞射來確定錯合物 [(dfpz)2Ir(fppz)] (1a) 和 [(fmpz)2Ir(hptz)] (3d) 的結構。最後利用 steady-state, relaxation dynamics, 以及理論計算發現這系列錯合物的發光效率會如此差的主要原因是來自於在T1 能階時，銥金屬與配位基間的鍵結變弱會導致 T1 能階較shallow 而能量容易以非放光的形式回到基態而促使能量快速的散失。 第二部份，我們以新穎的方法合成出一系列同型的銥金屬錯合物，預期可以控制其發光團來得到藍光的錯合物。在實驗的合成上，我們只能單獨得到 meridional 的結構。相對於大多數的電中性銥金屬錯合物只有單一最大放射波長，這系列錯合物在溶液中隨著溫度的不同會有明顯的雙重最大放射波長。這樣的結果是我們沒有預期的，經由 intra-ligand charge transfer (ILCT) 到 ligand-to-ligand charge transfer (LLCT) 的轉移所形成的，而 LLCT 並不會導致發光效率的下降，但會有我們不希望的紅位移發生。 第三部份，利用兩個 2-(p-tolyl)pyridine 或 1-phenylisoquinoline 和 2-pyridyl pyrrole 配位基來合成出一系列高效率綠色或紅橘色磷光放光的銥金屬錯合物。

The first part of this paper report a series of heteroleptic Ir(III) metal complexes 1□3 bearing two N-phenyl-substituted pyrazoles and one 2-pyridyl pyrazole (or triazole) ligands were synthesized and characterized to attain highly efficient, room-temperature blue phosphorescence. X-ray structural analyses on complexes [(dfpz)2Ir(fppz)] (1a) and [(fmpz)2Ir(hptz)] (3d) were established to confirm their molecular structures. Our results, on the basis of steady-state, relaxation dynamics, and theoretical approaches, lead to a conclusion that, for complexes 1□3, the weakening of iridium metal□ligand bonding strength in the T1 state plays a crucial role for the fast deactivation. The second part of this paper report the synthesis and characterization of a new series of homoleptic tris-pyridyl azolate Iridium(III) complexes, with an anticipation to see symmetry restriction on such system, i.e. showing efficient blue phosphorescence with better color chromaticity. The synthetic scheme rendered solely meridional structures. In contrast to most neutral Ir(III) complexes possessing unique phosphorescence, dual phosphorescence was observed in solution, of which the intensity ratio and the associated relaxation dynamics show remarkable temperature dependence. The results lead us to propose an unexpectedly intra-ligand charge transfer (ILCT) to ligand-to-ligand charge transfer (LLCT) conversion, for which the LLCT has not only lowered the luminous efficiency, but also resulted in an unwanted bathochromatic shifting. The last part of this paper report a series of heteroleptic Ir(III) metal complexes 1□5 bearing two 2-(p-tolyl)pyridine or 1-phenylisoquinoline and one 2-pyridyl pyrrole ligands were synthesized and characterized to attain highly efficient green or reddish orange phosphorescence.