Tuning the luminescence of transition metal complexes with acyclic diaminocarbene ligands

Kinzhalov, Mikhail A.; Grachova, Elena V.; Luzyanin, Konstantin V.

doi:10.1039/d1qi01288f

Cited by 44 publications

(35 citation statements)

References 169 publications

(348 reference statements)

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“…Moreover, ADCs are known to be even stronger σ-donors than NHCs due to the larger N–C carbene –N angles, which decrease the 2s character while increasing the 2p character in the σ orbital. − Our group’s earliest efforts using ADCs to support luminescent metal complexes are represented by a series of bis-cyclometalated iridium complexes with chelated or cyclometalated ADC ancillary ligands, which include compounds that have efficient deep-blue phosphorescence . Similar structures have been investigated by Luzyanin’s group, − and ADCs have also been used as supporting ligands for cyclometalated platinum complexes . Recently, our group has demonstrated the beneficial effects of ADC ligands in blue-phosphorescent platinum acetylide complexes, describing two cis -[Pt(CNR)(ADC)(CCPh) 2 ] complexes ( 2a–2b ) derived from cis -[Pt(CNR) 2 (CCPh) 2 ] precursors ( 1a–1b ), as shown in Scheme .…”

Section: Introductionmentioning

confidence: 92%

Platinum(II)-Substituted Phenylacetylide Complexes Supported by Acyclic Diaminocarbene Ligands

et al. 2022

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We introduce phosphorescent platinum aryl acetylide complexes supported by tert-butyl-isocyanide and strongly σ-donating acyclic diaminocarbene (ADC) ligands. The precursor complexes cis-[Pt(CNtBu)2(CCAr)2] (4a–4f) are treated with diethylamine, which undergoes nucleophilic addition with one of the isocyanides to form the cis-[Pt(CNtBu)(ADC)(CCAr)2] complexes (5a–5f). The new compounds incorporate either electron-donating groups (4-OMe and 4-NMe2) or electron-withdrawing groups [3,5-(OMe)2, 3,5-(CF3)2, 4-CN, and 4-NO2] on the aryl acetylide. Experimental HOMO–LUMO gaps, estimated from cyclic voltammetry, span the range of 2.68–3.61 eV and are in most cases smaller than the unsubstituted parent complex, as corroborated by DFT. In the ADC complexes, peak photoluminescence wavelengths span the range of 428 nm (2a, unsubstituted phenylacetylide) to 525 nm (5f, 4-NO2-substituted), with the substituents inducing a red shift in all cases. The phosphorescence E 0,0 values and electrochemical HOMO–LUMO gaps are loosely correlated, showing that both can be reduced by either electron-donating or electron-withdrawing substituents on the aryl acetylides. The photoluminescence quantum yields in the ADC complexes are between 0.044 and 0.31 and the lifetimes are between 4.8 and 14 μs, a factor of 1.8–10× higher (for ΦPL) and 1.2–3.6× longer (for τ) than the respective isocyanide precursor (ΦPL = 0.014–0.12, τ = 2.8–8.2 μs).

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Section: Introductionmentioning

confidence: 92%

Platinum(II)-Substituted Phenylacetylide Complexes Supported by Acyclic Diaminocarbene Ligands

et al. 2022

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“…Here we showed that azide addition to bis-cyclometalated iridium bis-isocyanide compounds gives access to a diverse set of new structures, with the fate of the reaction controlled primarily by the substituent pattern on the isocyanide with a secondary effect of the cyclometalating ligand. Previous work using isocyanide functionalization as a synthetic strategy for cyclometalated iridium complexes exclusively involved nucleophilic addition of nitrogen-based reagents, which gives access to acyclic diaminocarbenes. ,, The reactions described here lead to more diverse outcomes, and presumably all initiate with a [3 + 2] azide-isocyanide cycloaddition. This cycloaddition can give a stable tetrazolato when the isocyanide is substituted with electron-donating groups, which is followed by N 2 extrusion to leave an aryl cyanamido with electron-withdrawing groups.…”

Section: Discussionmentioning

confidence: 99%

“…An emerging strategy in the design of cyclometalated iridium complexes and other classes of organometallic phosphors is to use ligand-based functionalization strategies to install supporting ligands not able to be accessed by traditional means. The best-developed example of this approach involves addition of a nitrogen-based nucleophile to a coordinated isocyanide, which forms an acyclic diaminocarbene (ADC). , Our group has used this method to install ADCs onto luminescent iridium , or platinum , complexes and showed the strong σ-donor ADCs are particularly effective at supporting efficient deep-blue phosphorescence, , and related approaches have been used to good effect by a few other groups in the design of iridium, , rhenium, or platinum , phosphors supported by ADCs.…”

Section: Introductionmentioning

confidence: 99%

Substituent-Dependent Azide Addition to Isocyanides Generates Strongly Luminescent Iridium Complexes

et al. 2023

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Ligand-centered functionalization reactions offer diverse strategies to prepare luminescent organometallic compounds. These compounds can have unique structures that are not accessible via traditional coordination chemistry and can possess enhanced or unusual photophysical properties. Here we show that bis-cyclometalated iridium bis-isocyanide complexes (1) react with azide (N3 –) to form novel luminescent structures. The fate of the reaction with azide is determined primarily by the substituent on the aryl isocyanide. Those with electron-withdrawing substituents (CF3 or NO2) react with 1 equiv of azide followed by N2 extrusion, forming aryl cyanamido products (2). With electron-donating groups on the aryl isocyanide the reactivity is more diverse, and three outcomes are possible. In two cases, the isocyanide and azide undergo a [3 + 2] cycloaddition to form a C-bound tetrazolato structure (3). In three other cases, 2 equiv of azide are involved in the formation of a previously unobserved structure, where a tetrazolato and aryl cyanamido couple and rearrange to form a chelating ligand comprised of an N-bound tetrazolato and an acyclic diaminocarbene (4). Finally, a bimetallic aryl cyanamido complex (5) is isolated in one case. All compounds are luminescent, some with exceptional photoluminescence quantum yields as high as 0.81 in solution for sky-blue emission, and 0.87 for yellow emission and 0.65 for orange-red emission in polymer films.

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“…Transition metal-based luminescent materials are a subject of rapidly growing interest in view of their applications for design and fabrication of solid-state lighting devices, − in chemosensoring, − and as photocatalysts. − Efficient room temperature (RT) phosphorescence of transition-metal species is conventionally attributed to the heavy atom effect that induces strong spin–orbit coupling, which facilitates both fast intersystem crossing and the formally spin-forbidden triplet radiative decay. − The photophysical and photochemical properties of transition-metal species, particularly those of platinum(II), have been analyzed in a number of reviews. ,,− …”

Section: Introductionmentioning

confidence: 99%

Polymorph-Dependent Phosphorescence of Cyclometalated Platinum(II) Complexes and Its Relation to Non-covalent Interactions

et al. 2022

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Cyclometalated platinum(II) complexes [Pt(ppy)Cl(CNAr)] (ppy = 2-phenylpyridinato-C 2 , N ; Ar = C 6 H 4 -2-I 1 , C 6 H 4 -4-I 2 , C 6 H 3 -2-F-4-I 3 , and C 6 H 3 -2,4-I 2 4 ) bearing ancillary isocyanide ligands were obtained by the bridge-splitting reaction between the dimer [Pt(ppy)(μ-Cl)] 2 and 2 equiv any one of the corresponding CNAr. Complex 2 was crystallized in two polymorphic forms, namely, 2 I and 2 II , exhibiting green (emission quantum yield of 0.5%) and orange (emission quantum yield of 12%) phosphorescence, respectively. Structure-directing non-covalent contacts in these polymorphs were verified by a combination of experimental (X-ray diffraction) and theoretical methods (NCIplot analysis, combined electron localization function (ELF), and Bader quantum theory of atoms in molecules (QTAIM analysis)). A noticeable difference in the spectrum of non-covalent interactions of 2 I and 2 II is seen in the Pt···Pt interactions in 2 II and absence of these metallophilic contacts in 2 I . The other solid luminophores, namely, 1 , 3 I–II , 4 , and 4 ·CHCl 3 , exhibit green luminescence; their structures include intermolecular C–I···Cl–Pt halogen bonds as the structure-directing interactions. Crystals of 1 , 2 I , 3 I , 3 II , 4 , and 4 ·CHCl 3 demonstrated a reversible mechanochromic color change achieved by mechanical grinding (green to orange) and solvent adsorption (orange to green).

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Tuning the luminescence of transition metal complexes with acyclic diaminocarbene ligands

Abstract: Organometallics featuring acyclic diaminocarbene (ADC) ligands have recently emerged as powerful emitters for use in OLEDs and other electroluminescent technologies. Owing to strong σ-donor properties and broad synthetic availability, ADCs...

Cited by 44 publications

References 169 publications

Platinum(II)-Substituted Phenylacetylide Complexes Supported by Acyclic Diaminocarbene Ligands

Platinum(II)-Substituted Phenylacetylide Complexes Supported by Acyclic Diaminocarbene Ligands

Substituent-Dependent Azide Addition to Isocyanides Generates Strongly Luminescent Iridium Complexes

Polymorph-Dependent Phosphorescence of Cyclometalated Platinum(II) Complexes and Its Relation to Non-covalent Interactions

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