Studies of the 5‘-Substituted Phenylisoquinoline-Based Iridium Complexes Using Density Functional Theory

Abstract

To examine the effects of coordination sites and the nature of ligands reported for color-tuning of a few cyclometalated Ir(III) complexes, a series of 3′-substituted (F, CH 3 , OCH 3 , and CF 3 ) phenylisoquinoline (piq) ligands were synthesized and successfully used to prepare iridium complexes, including bis[1-(5′-methyl)phenylisoquinolinato-N,, and bis[1-(5′-fluoro)phenylisoquinolinato-N,C 2′ ]iridium(III) (acetylacetonate) (6a4). Density functional theory results indicate that two conflicting effects, electronic and steric, can be applied to account for the substitution-sensitive coordination sites of piq: the methoxyl-or fluoro-substituted ligand generates both 2′-coordinated and 6′-coordinated isomers. Coordination of methoxy substitution prefers 6′-coordination of piq dominated by steric effects, while coordination of fluoro substitution prefers 2′-coordination, arising from better back-donation of the iridium center. Correlations of HOMO-LUMO gaps with electroluminescence (EL) data are discussed. More importantly, the EL data are well predicted by time-dependent density functional theory calculations.

Spectroscopic properties of cyclometallated iridium complexes by TDDFT

“…Information about the HOMO and LUMO is also often used to estimate the nature of the lowest excited states, assuming a single orbital picture of the electronic transitions. Conversely to ground state DFT calculations, TDDFT excited state calculations on iridium(III) complexes are scarce [8,[33][34][35][36][37], the first paper in the subject being the work by Hay [33] on the neutral [Ir(ppy) 3 ] complex, and the literature in this field is generally less developed than for the analogous d 6 ruthenium(II) compounds [38]. While TDDFT is more computationally demanding than ground state DFT calculations, it provides a more accurate description of the excitation energies and excited states than a one-particle approximation, since within TDDFT the description of the excited states is based on a linear combination of single occupied-to-virtual orbital excitations, therefore providing information beyond a simple HOMO-LUMO picture.…”

Excited States from Time‐Dependent Density Functional Theory

“…Most are in the linear response regime. In inorganic chemistry, the optical response of many transition metal complexes [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] has been calculated, as have some X-ray absorption spectra. 36,37 In organic chemistry, heterocycles [38][39][40][41][42][43] have been examined among others, [44][45][46] including the response of thiouracil, 47 s-tetrazine, 48 and annulated porphyrins.…”

Crystal structure of bis[2-(2-naphthyl)-4,6-dimethylpyrimidinyl- k2C,N](dibenzoylmethanato)iridium(III) - n-hexane (1:1), [Ir(C16H13N2)2(C15H11O2)] · C6H14

“…The crystal structure analysis of the title compound shows adistorted octahedral coordination of the iridium ( [7,8]. In the title crystal structure, there exist intermolecular C-H×××Nh ydrogen bonds (H45···N1 =2.617 Å, 160.5°), causingadimeric structure.…”

“…b-Diketonates as ancillaryligands canbean effectivew ay to improvet he properties of bis-cyclometalated Ir(III) complexes [3,4]. As is known, theIr(III) Cl-bridged dimers were directly subjected to bridge-splitting reaction with bdiketonates to produce the mononuclear bis-cyclometalated Ir(III) diketonate complexes [5][6][7][8].…”

“…b-Diketonates as ancillaryligands canbean effectivew ay to improvet he properties of bis-cyclometalated Ir(III) complexes [3,4]. As is known, theIr(III) Cl-bridged dimers were directly subjected to bridge-splitting reaction with bdiketonates to produce the mononuclear bis-cyclometalated Ir(III) diketonate complexes [5][6][7][8].The crystal structure analysis of the title compound shows adistorted octahedral coordination of the iridium ( [7,8]. In the title crystal structure, there exist intermolecular C-H×××Nh ydrogen bonds (H45···N1 =2.617 Å, 160.5°), causingadimeric structure.…”