Substituent effects on the photophysical and electrochemical properties of iridium(III) complexes containing an arylcarbazolyl moiety

Trifluoromethyl-substituted cyclometalated iridiumIII emitters with high photostability for continuous oxygen sensing

“…Table 2 shows that the HOMOs mainly consist of the iridium center and the phenyl rings of the cyclometalating ligands, while the LUMOs are on the rings of all the cyclometalating ligands. [32][33][34] The introduction of the strong electron-withdrawing -CF 3 group tends to stabilize the HOMO by removing electron density from the metal and also to decrease the energy of the LUMO by increasing the electron affinity of the parent ligand. 35 The DFT-estimated HOMO-LUMO gaps for Lx3 and Lx4 also indicate that the -CF 3 moiety on the pyridyl ring lowers the LUMO level more significantly than the HOMO level, resulting in a decrease in the energy gap.…”

“…The targeted Ir(III) emitting materials were obtained using a previously reported method. 33 IrCl 3 Á3H 2 O and 2.5 equiv. of cyclometalating ligand were added to a mixture of 2-ethoxyethanol and water (3 : 1 in volume) to 110 1C for 24 h. Upon cooling to room temperature, the yellow precipitate was collected by filtration and washed with water.…”

Novel Emission Color‐Tuning Strategies in Heteroleptic Phosphorescent Ir(III) and Pt(II) Complexes

“…The broad range of color‐tuning from blue‐green (complex 43 , λ =487 nm) to red (complex 42 , λ =607 nm) was realized. Interestingly, complexes 41 and 50 with the electron‐accepting B(Mes) 2 groups on the phenyl rings show a significant bathochromic effect in their emission wavelength compared to their parent complexes 13 and 4 (Figure ), which is completely in contrast to the reported results based on the conventional color‐tuning principle . The calculated MO patterns of complexes 41 and 50 show that the pyridyl‐oriented MLCT character in the conventional ppy‐type Ir(III) complexes is largely changed due to the fact that the π‐accepting B(Mes) 2 moieties offer a favorable venue for electrons in the MLCT transitions to facilitate the MLCT transition process and stabilize the MLCT states (Figures , a and 10b) .…”

“…With the aim to distinguish the novel color‐tuning strategies, we firstly give a brief account on the well‐established conventional color‐tuning strategies for the ppy‐type phosphorescent Ir(III) and Pt(II) complexes. Generally, the conventional color‐tuning strategies are based on the molecular orbital (MO) patterns of these complexes . Typically, the HOMOs of these ppy‐type phosphorescent complexes are mainly composed of the d ‐orbitals of the metal center and the π ‐orbitals of C ‐chelated block in the ppy‐type ligand, while the LUMOs principally reside on the π *‐orbitals of N ‐chelated unit of the ppy‐type ligand .…”

Cyclometalation Geometry of the Bridging Ligand as a Tuning Tool for Photophysics of Dinuclear Ir(III) Complexes

“…The emission color can be fine-tuned via the substituent patterns on the ligand affecting the energies of the Frontier molecular orbitals and, consequently, the energy of the emitting state. 2,3 The size of the π-conjugated system of the chromophoric ligand is another parameter that strongly affects the characteristics of the complex's phosphorescence. 1 It was shown in the literature that functionalization of the cyclometalating het(aryl) with additional π-excessive cycles can afford a strong red shift of emission which, however, comes with a significant reduction of the phosphorescence rate and enhanced efficiency of nonradiative relaxation processes.…”