Spectroscopic, Electrochemical and DFT Studies of Phosphorescent Homoleptic Cyclometalated Iridium(III) Complexes Based on Substituted 4-Fluorophenylvinyl- and 4-Methoxyphenylvinylquinolines

Adeloye, Adewale O.; Mphahlele, Malose J.; Adekunle, Abolanle S.; Rhyman, Lydia; Ramasami, Ponnadurai

doi:10.3390/ma10101061

Cited by 9 publications

(5 citation statements)

References 60 publications

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“…The predicted effects of quinoxaline ligand substitution were investigated by examining the energy values of the HOMO and LUMO for each of the complexes (Table ). Electron-withdrawing groups are known to have a stabilizing effect on the metal-dominated HOMO through removal of the electron density, while electron-donating groups have the inverse effect . Here, those complexes possessing quinoxaline ligands with electron-withdrawing groups (e.g., F, Cl) exhibit lower-energy values for the frontier orbitals.…”

Section: Resultsmentioning

confidence: 59%

Spectroscopic and Theoretical Investigation of Color Tuning in Deep-Red Luminescent Iridium(III) Complexes

et al. 2020

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A series of heteroleptic, neutral iridium(III) complexes of the form [Ir(L) 2 (N^O)] (where L = cyclometalated 2,3-disubstituted quinoxaline and N^O = ancillary picolinate or pyrazinoate) are described in terms of their synthesis and spectroscopic properties, with supporting computational analyses providing additional insight into the electronic properties. The 10 [Ir(L) 2 (N^O)] complexes were characterized using a range of analytical techniques (including 1 H, 13 C, and 19 F NMR and IR spectroscopies and mass spectrometry). One of the examples was structurally characterized using X-ray diffraction. The redox properties were determined using cyclic voltammetry, and the electronic properties were investigated using UV−vis, time-resolved luminescence, and transient absorption spectroscopies. The complexes are phosphorescent in the red region of the visible spectrum (λ em = 633−680 nm), with lifetimes typically of hundreds of nanoseconds and quantum yields ca. 5% in aerated chloroform. A combination of spectroscopic and computational analyses suggests that the long-wavelength absorption and emission properties of these complexes are strongly characterized by a combination of spinforbidden metal-to-ligand charge-transfer and quinoxaline-centered transitions. The emission wavelength in these complexes can thus be controlled in two ways: first, substitution of the cyclometalating quinoxaline ligand can perturb both the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital levels (LUMO, Cl atoms on the ligand induce the largest bathochromic shift), and second, the choice of the ancillary ligand can influence the HOMO energy (pyrazinoate stabilizes the HOMO, inducing hypsochromic shifts).

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Section: Resultsmentioning

confidence: 59%

Spectroscopic and Theoretical Investigation of Color Tuning in Deep-Red Luminescent Iridium(III) Complexes

et al. 2020

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“…In spite of the apparent value of evaluating the emission of cyclometalated iridium complexes embedded into polymer thin films, this method is only used sporadically when new compounds are evaluated. Several prominent studies of bis-cyclometalated iridium complexes include emission data in PMMA film, ,− in addition to very few reports which include data for neat solid samples of cyclometalated iridium complexes. − The majority of reports on new cyclometalated iridium complexes only include photoluminescence in solution, and even those which present spectra for polymer film or solid samples do not always include quantum yield and lifetime data. Furthermore, while it is not uncommon to observe quantum yield enhancements when the complex is immobilized in a polymer, there are no systematic studies on what characteristics of the iridium complex, namely its charge, emission color, and nature of its excited state, determine to what extent the quantum yield and radiative/nonradiative rate constants change in a polymer thin film.…”

Section: Introductionmentioning

confidence: 99%

Photoluminescence of Cyclometalated Iridium Complexes in Poly(methyl methacrylate) Films

Lai

Cañada

et al. 2018

Organometallics

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In this work, we describe the emission properties of 12 heteroleptic bis-cyclometalated iridium complexes immobilized in poly(methyl methacrylate) (PMMA) thin films. The compounds chosen for this study span a range of emission colors covering the visible spectrum and fall into three categories with electronically diverse ancillary ligandsfour cationic bis(aryl isocyanide) complexes, four with chelating bis(acyclic diaminocarbene) (bis-ADC) ancillary ligands which can exist in two protonation states, and four neutral compounds with monoanionic, strongly π donating β-ketoiminate (acNac) and β-diketiminate (NacNac) ancillary ligands. Included in this suite of compounds are five new compounds, one with two aryl isocyanide ancillary ligands, two with bis-ADC ancillary ligands, and one each with acNac and NacNac; their syntheses are described, and crystal structures of three are presented. The bulk of the work presented here describes the emission spectra of all 12 compounds, comparing spectral features in solution to those in thin PMMA films (2 wt % of the respective iridium complex). The emission wavelengths and spectral profiles do not change substantially in PMMA films, but in most cases there are dramatic (2-fold to more than 10-fold) increases in photoluminescence quantum yields, with many of the compounds approaching unity quantum yield in PMMA. The increases in quantum yield come from a combination of larger radiative rates and smaller nonradiative rates in the thin film samples, with significant differences between the members of this series of compounds.

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“…Similar to Scheme 6, the group further investigated multilayered organic light-emitting diodes characteristics of complexes 21 – 25 , where extension of π-conjugation was simply made of phenyl- and methyl-substitution on cyclometalating ligand. The homoleptic and heteroleptic complexes obtained were then compared to an acetylated analogue derivative ( 25 ) to obtain red phosphorescent materials at wavelength maxima range of 510–690 nm [60,61,62,63,64].…”

Section: Comparative Analysis Of Mono- and Bidentate Ligands Functmentioning

confidence: 99%

Exploration of the Structural and Photophysical Characteristics of Mono- and Binuclear Ir(III) Cyclometalated Complexes for Optoelectronic Applications

Adeloye

2019

Materials

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Intrinsic characteristics possessed and exhibited by Ir(III) cyclometalated complexes need to be further examined, understood, and explored for greater value enhancement and potentiation. This work focuses primarily on the comparative studies of the ligand structures, types, and their substituent influence on the photophysical and optoelectronic properties of typical cyclometalated mono- and binuclear iridium(III) complexes in solution or solid states.

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Spectroscopic, Electrochemical and DFT Studies of Phosphorescent Homoleptic Cyclometalated Iridium(III) Complexes Based on Substituted 4-Fluorophenylvinyl- and 4-Methoxyphenylvinylquinolines

Cited by 9 publications

References 60 publications

Spectroscopic and Theoretical Investigation of Color Tuning in Deep-Red Luminescent Iridium(III) Complexes

Spectroscopic and Theoretical Investigation of Color Tuning in Deep-Red Luminescent Iridium(III) Complexes

Photoluminescence of Cyclometalated Iridium Complexes in Poly(methyl methacrylate) Films

Exploration of the Structural and Photophysical Characteristics of Mono- and Binuclear Ir(III) Cyclometalated Complexes for Optoelectronic Applications

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