Photo- and Electroluminescent Neutral Iridium(III) Complexes Bearing Imidoylamidinate Ligands

Abstract

Imidoylamidinate-based heteroleptic bis(2phenylbenzothiazole)iridium(III) and -rhodium(III) complexes [(bt) Ir4); yields 70−84%) were obtained by the reaction of the in situ-generated solvento-complex [(bt) 2 M-(NCMe) 2 ]NO 3 and benzo[d]thia/oxa/N-methylimidozol-2amines in the presence of NaOMe. Complexes Ir1−4 exhibited intense orange photoluminescence, reaching 37% at room temperature quantum yields, being immobilized in a poly(methyl methacrylate) matrix. A photophysical study of these species in a CH 2 Cl 2 solution, neat powder, and frozen (77 K) MeOC 2 H 4 OH− EtOH glass matrixalong with density-functional theory (DFT), ab initio methods, and spin−orbit coupling time-dependent DFT calculationsverified the effects of substitution in the imidoylamidinate ligands on the excited-state properties. Electrochemical (cyclic voltammetry and differential pulse voltammetry) and theoretical DFT studies demonstrated noninnocent behavior of the imidoylamidinate ligands in Ir1−4 and Rh1 complexes due to the significant contribution coming from these ligands in the HOMO of the complexes. The iridium(III) species exhibit a ligand (L, 2-phenylbenzothiazole)-centered ( 3 LC), metal-to-ligand (L′, imidoylamidinate) charge-transfer ( 3 ML′CT, 3 MLCT) character of their emission. The imidoylamidinate-based iridium(III) species were proved to be effective as the emissive dopant in an organic light-emitting diode device, fabricated in the framework of this study.

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

“…From the single crystals, these complexes share slightly distorted octahedral configurations with the cis coordination mode for the metalated carbon atoms and the trans coordination mode for nitrogen atoms on the cyclometalated ligands, which is the same as the reported examples . As far as we know, this is the first example reporting three separable isomeric iridium(III) complexes realized by the one-pot synthesis. − …”

“…The incorporation of the fluorine atoms onto the metalated phenyl ring of (ppy) 2 Ir(acac) and the replacement of its acetylacetonate ligand with picolinic acid could realize a blue emissive iridium(III) complex bis (4,6-difluorophenylpyridine) (picolinate)iridium(III) . For the substituent modification approach, it usually provides more opportunities to tune the excited states of complexes by properly selecting the substituents or incorporating the substituents onto the appropriate position of the complex. , At the same time, the coordination of the iridium(III) ion with substituent-bearing ligands almost results in a sole product (no isomeric complex formed) via (selective) cyclometalation, which is originated from the steric hindrance of substituents (Scheme ). − Recently, a series of methoxyl/nitrile-functionalized phenylbenzimidazole-based iridium(III) complexes were developed .…”

“…For the substituent modification approach, it usually provides more opportunities to tune the excited states of complexes by properly selecting the substituents or incorporating the substituents onto the appropriate position of the complex. , At the same time, the coordination of the iridium(III) ion with substituent-bearing ligands almost results in a sole product (no isomeric complex formed) via (selective) cyclometalation, which is originated from the steric hindrance of substituents (Scheme ). − Recently, a series of methoxyl/nitrile-functionalized phenylbenzimidazole-based iridium(III) complexes were developed . As expected, only one product was formed by selective cyclometalation, and no isomer was found, although two possible metalation sites on these ligands exist .…”

“…Phosphorescent transition-metal complexes (PTMCs) are one of the most important luminescent materials . Among PTMCs, the phosphorescent iridium­(III) complexes have received much attention because of their high chemical stability, easy tunability in excited states, highly emissive triplet excited states enabled by the effective spin–orbit coupling effect, etc., which have been extensively involved in many fields including organic electroluminescence (EL), catalysis, bioimaging, and cancer therapy. − The continuous efforts on the molecular design of iridium­(III) complexes greatly speed up their developments for practical applications.…”

AIPE-active cationic Ir(iii) complexes for efficient detection of 2,4,6-trinitrophenol and oxygen

“…2-Phenylbenzothiazole is a general ligand framework for the construction of Ir(III) complexes. [42][43][44] A few neutral Ir(III) complexes containing 2-phenylbenzothiazole ligands have been successfully applied in oxygen sensing. [45][46][47] On the other hand, the diphenylamino (DPA) group has been proved to be an efficient functional substituent for tuning the properties of phosphorescent materials.…”