One-Pot Synthesis of Acetylacetonate-Based Isomeric Phosphorescent Cyclometalated Iridium(III) Complexes via Random Cyclometalation: A Strategy for Excited-State Manipulation

Abstract

The excited-state manipulation of the phosphorescent iridium(III) complexes plays a vital role in their photofunctional applications. The development of the molecular design strategy promotes the creative findings of novel iridium(III) complexes. The current molecular design strategies for iridium(III) complexes mainly depend on the selective cyclometalation of the ligands with the iridium(III) ion, which is governed by the steric hindrance of the ligand during the cyclometalation. Herein, a new molecular design strategy (i.e., random cyclometalation strategy) is proposed for the effective excited-state manipulation of phosphorescent cyclometalated iridium(III) complexes. Two series of new and separable methoxyl-functionalized isomeric iridium(III) complexes are accessed by a one-pot synthesis via random cyclometalation, resulting in a dramatic tuning of the phosphorescence peak wavelength (∼57 nm) and electrochemical properties attributed to the high sensitivity of their excited states to the position of the methoxyl group. These iridium(III) complexes show intense phosphorescence ranging from the yellow (567 nm) to the deep-red (634 nm) color with high photoluminescence quantum yields of up to 0.99. Two deep-red emissive iridium(III) complexes with short decay lifetimes are further utilized as triplet emitters to afford efficient solution-processed electroluminescence with reduced efficiency roll-offs.

Rational design of efficient photosensitizers based on cyclometalated iridium(iii) complexes with 2-arylbenzimidazole and aromatic 1,3-diketone ligands

“…Thus, this mixture of heteroleptic complexes was not studied because the photophysical properties of such isomeric complexes may be significantly influenced by the substituent position. 49…”

“…Thus, this mixture of heteroleptic complexes was not studied because the photophysical properties of such isomeric complexes may be significantly influenced by the substituent position. 49 Complexes 1, 2, 5, 7-10, 12, and 13 were characterized by single-crystal X-ray diffraction. In all the cases, the analysis revealed the expected molecular structures of the heteroleptic bis-cyclometalated complexes possessing a distorted octahedral coordination environment of the Ir(III) ion with a trans-N,N arrangement (Fig.…”

Efficient 1-(thiophen-2-yl)isoquinoline-based ionic iridophosphors with bulky counterions for solution-processed deep-red electroluminescence

“…S2 †), the LUMO and HOMO levels of Ira and Irb are all within those of the Bepp 2 host, and the triplet energy level of the Bepp 2 host is higher than those of the two complexes, suggesting good carrier trapping in the light-emitting layers. 25,26 No residual emission from the Bepp 2 host was observed, proving that the complete energy transfer from the e Estimated from the highest-energy vibronic sub-band of the phosphorescence spectrum at 1.0 × 10 −5 mol L −1 in CH 2 Cl 2 at 77 K, λ ex = 365 nm.…”

“…Bepp 2 host to the iridium(III) cations occurred in these devices. 25,26 As depicted in Fig. 5b and S3, † the maximum brightnesses of the devices based on Ira and Irb are 4792 and 5046 cd m −2 , respectively.…”

Controlling the sensitivity and selectivity for the detection of nitro-based explosives by modulating the electronic substituents on the ligand of AIPE-active cyclometalated iridium(iii) complexes

“…[43][44][45]53 Cyclometalated complexes of iridium(III) provide a good platform to tune the emission wavelength and quantum yield simply by varying the electronic substituents at various positions of the cyclometalated ring. [59][60][61][62][63][64] In this work, substitution on the phenyl portion of the cyclometalated ring is accomplished by following two approaches: (1) shifting of emission maxima to enhance the resonance overlap and (2) reducing the LUMO energy level towards the LUMO of a specific nitro explosive to enable efficient electron transfer between the donor and acceptor. Here, four AIE active Ir(III) complexes have been synthesized by varying the electronic substituents on the parent complex and the suitability of these for the detection of nitro explosives is studied.…”