Blue-green emissive cationic iridium(<scp>iii</scp>) complexes using partially saturated strongly-donating guanidyl-pyridine/-pyrazine ancillary ligands

Hasan, Kamrul; Pal, Amlan K.; Auvray, Thomas; Zysman‐Colman, Eli; Hanan, Garry S.

doi:10.1039/c5cc04069h

Cited by 25 publications

(26 citation statements)

References 45 publications

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“…For our strategy we used guanidylpyridine, gpy, (53 and 54) or guanidylpyrazine, gpz, 55ancillary ligands, wherein one of the coordinating heterocyclic rings is partially saturated and thus reduces the conjugation length of the ligand. 54 In DFT calculations point to a LUMO that is largely localized on the electron-poor pyrazine ring, resulting in both a much lower emission energy (λ PL = 640 nm) and a very low Φ PL of 0.2%. was observed for the six ppy-containing complexes studied, regardless of the nature of the P^P ligand.…”

Section: : N^n Ligand -Effect Of Substitution/modification Of the Bpymentioning

confidence: 99%

Lessons learned in tuning the optoelectronic properties of phosphorescent iridium(iii) complexes

2017

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This perspective illustrates our approach in the design of heteroleptic cationic iridium(iii) complexes for optoelectronic applications, especially as emitters in electroluminescent devices. We discuss changes in the photophysical properties of the complexes as a consequence of modification of the electronics of either the cyclometalating (C^N) or the ancillary (N^N) ligands. We then broach the impact on these properties as a function of modification of the structure of both types of ligands. We explain trends in the optoelectronic behaviour of the complexes using a combination of rationally designed structure-property relationship studies and theoretical modelling that serves to inform subsequent ligand design. However, we have found cases where the design paradigms do not always hold true. Nevertheless, all these studies contribute to the lessons we have learned in the design of heteroleptic cationic phosphorescent iridium(iii) complexes.

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Section: : N^n Ligand -Effect Of Substitution/modification Of the Bpymentioning

confidence: 99%

Lessons learned in tuning the optoelectronic properties of phosphorescent iridium(iii) complexes

2017

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“…[12][13][14][15][16][17][18][19][20][21] Their emission spectra can be readily tuned by altering either the ancillary or 2-phenylpyridine ( ppy) ligand. [24][25][26][27][28][29][30][31][32][33] There are also many examples where the ppy core has been modified to induce blue or red shifts in the emission spectrum. However, there are now numerous other bidentate and monodentate ligands known that can induce more significant red or blue shifts than these two examples.…”

Section: Introductionmentioning

confidence: 99%

The use of organolithium reagents for the synthesis of 4-aryl-2-phenylpyridines and their corresponding iridium(iii) complexes

et al. 2016

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A versatile palladium-free route for the synthesis of 4-aryl-substituted phenylpyridines (ppy), starting from tert-butyl 4-oxopiperidine-1-carboxylate, is reported. Reaction with an aryllithium, followed by trifluoroacetic acid dehydration/deprotection and oxidation with 2-iodoylbenzoic acid and finally phenylation, gave 4 ligands (L(1-4)H): 2,4-diphenylpyridine, 4-(4-methoxyphenyl)-2-phenylpyridine, 2-phenyl-4-(o-tolyl)pyridine and 4-mesityl-2-phenylpyridine. These ligands were coordinated to iridium to give the corresponding Ir(L)2(A) complexes (Ir1-7), where A = ancillary ligand acetylacetate or 2-picolinate. This was used to demonstrate that, through a combination of ancillary ligand choice and torsional twisting between the 4-aryl substituents of the ppy ligands, it is possible to tune the phosphorescent emission of the complexes in the range 502-560 nm.

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“…[14][15][16][17][18][19][20] Most of the reported complexes fall into two classes; neutral homoleptic Ir III (C^N) 3 and heteroleptic Ir III (C^N) 2 (L-X) (C^N = cyclometalating ligand; L-X = monoanionic ancillary ligand), 8,9,[21][22][23][24][25][26][27][28][29][30][31][32] and monocationic heteroleptic species [Ir III (C^N) 2 (L-L)] + (L-L = neutral bidentate ligand). 7,[11][12][13][33][34][35][36][37][38][39][40] The emission properties of the latter are tuned readily, and various strategies have been adopted. These include changing the degree of π-conjugation in the ligands, 34 incorporating electron-rich S-heterocycles, [41][42][43][44] or most commonly, functionalising C^N or L-L to adjust the energies of the metal and ligand orbitals.…”

Section: Introductionmentioning

confidence: 99%

Cyclometalated Ir(iii) complexes of deprotonated N-methylbipyridinium ligands: effects of quaternised N centre position on luminescence

et al. 2015

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Six new tricationic Ir(III) complexes of cyclometalating ligands derived from 1-methyl-2-(2'-pyridyl)pyridinium or 1-methyl-4-(2'-pyridyl)pyridinium are described. These complexes of the form [Ir(III)(C^N)2(N^N)](3+) (C^N = cyclometalating ligand; N^N = α-diimine) have been isolated and characterised as their PF6(-) and Cl(-) salts. Four of the PF6(-) salts have been studied by X-ray crystallography, and structures have been obtained also for two complex salts containing MeCN and Cl(-) or two Cl(-) ligands instead of N^N. The influence of the position of the quaternised N atom in C^N and the substituents on N^N on the electronic/optical properties are compared with those of the analogous complexes where C^N derives from 1-methyl-3-(2'-pyridyl)pyridinium (B. J. Coe, et al., Dalton Trans., 2015, 44, 15420). Voltammetric studies reveal one irreversible oxidation and multiple reduction processes which are mostly reversible. The new complexes show intramolecular charge-transfer absorptions between 350 and 450 nm, and exhibit bright green luminescence, with λmax values in the range 508-530 nm in both aqueous and acetonitrile solutions. In order to gain insights into the factors that govern the emission properties, density functional theory (DFT) and time-dependent DFT calculations have been carried out. The results confirm that the emission arises largely from triplet excited states of the C^N ligand ((3)LC), with some triplet metal-to-ligand charge-transfer ((3)MLCT) contributions.

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Blue-green emissive cationic iridium(iii) complexes using partially saturated strongly-donating guanidyl-pyridine/-pyrazine ancillary ligands

Cited by 25 publications

References 45 publications

Lessons learned in tuning the optoelectronic properties of phosphorescent iridium(iii) complexes

Lessons learned in tuning the optoelectronic properties of phosphorescent iridium(iii) complexes

The use of organolithium reagents for the synthesis of 4-aryl-2-phenylpyridines and their corresponding iridium(iii) complexes

Cyclometalated Ir(iii) complexes of deprotonated N-methylbipyridinium ligands: effects of quaternised N centre position on luminescence

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