Synthesis and photophysical properties of linear gold(<scp>i</scp>) complexes based on a CCC carbene

Romanov, Alexander S.; Linnolahti, Mikko; Bochmann, Manfred

doi:10.1039/d1dt03393j

Cited by 8 publications

(12 citation statements)

References 36 publications

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“…Carbene‐metal‐amides (CMAs) [ 1–18 ] have recently emerged as a new type of donor‐bridge‐acceptor materials demonstrating unity luminescence quantum yields and short excited state lifetime (<1 µs) and show great promise for realizing energy efficient organic light‐emitting diodes (OLEDs). The molecular design of CMA emitters is reminiscent of the donor–acceptor strategy applied in organic thermally activated delayed fluorescence (TADF) materials.…”

Section: Introductionmentioning

confidence: 99%

“…Carbene-metal-amides (CMAs) [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] have recently emerged as a new type of donor-bridge-acceptor materials demonstrating unity luminescence quantum yields and short excited state lifetime (<1 µs) and show great promise for realizing energy efficient organic light-emitting diodes (OLEDs). The molecular conversion between 1 CT and 3 CT states requires involvement of a 3 LE state [23][24][25] ideally resonant with the manifold of the CT states.…”

Section: Introductionmentioning

confidence: 99%

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Donor N‐Substitution as Design Principle for Fast and Blue Luminescence in Carbene‐Metal‐Amides

Reponen

Chotard

Lempelto

et al. 2022

Advanced Optical Materials

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design of CMA emitters is reminiscent of the donor-acceptor strategy applied in organic thermally activated delayed fluorescence (TADF) materials. [19,20] Organic TADF materials have attracted enormous research interest since Adachi et al. showed they could be used in high-efficiency OLED devices. [20] Unlike organic TADF emitters, the carbene (acceptor) and amide (donor) ligands in CMA materials are bridged by a coinage metal atom that not only enables rotational flexibility between donor and acceptor but also, by virtue of its spin-orbit coupling (SOC) coefficient, greatly accelerates intersystem crossing (ISC) rates, leading to short excited state lifetimes. Since the highest occupied molecular orbital (HOMO) is mainly localized on the amide and the LUMO on the carbene and both are thus spatially decoupled, this molecular design minimizes the exchange energy between emissive intramolecular charge-transfer (CT) states and promotes efficient reverse ISC (rISC) between singlet and triplet states of CT character. [9,10] The computations on gold-centered CMAs have indicated a direct 1 CT-3 CT pathway enabled by strong SOC from the metal bridge. Conversely, the presence of a nearby locally excited triplet state ( 3 LE) slows down emission kinetics. [9,10] This finding contrasts with one of the current interpretations of emission in organic TADF materials [21,22] where it has been proposed that A series of gold-centered carbene-metal-amide (CMA) complexes are synthesized with the carbazole donor ligand modified by substitution with nitrogen atoms in varying positions. The luminescence of new aza-CMA complexes shows a significant blueshift depending on the position of the N atom, to provide bright blue-green (500 nm), sky-blue (478 nm), blue (450 nm) and deep-blue (419 nm) light-emitters. The impact of the electron-withdrawing aza-group on the nature of the luminescence and the excited state energies of the locally excited (LE) or charge transfer (CT) states have been interpreted with the help of transient absorption, in-depth photoluminescence experiments and theoretical calculations. By considering the orbital characters of the lowest CT and LE states, we develop a new concept for simultaneous energy tuning for both of these states with a single aza-substitution, allowing for fast and blue CT emission. This concept allows the interference of 3 LE phosphorescence to be avoided at room temperature. The approach is extended to two N substitutions at the optimal location in the 3-and 6-positions of the carbazole skeleton. These results suggest a practical molecular design towards the development of bright and deep-blue emitting CMA materials to tackle the stability problem of energy-efficient deep-blue OLEDs.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Donor N‐Substitution as Design Principle for Fast and Blue Luminescence in Carbene‐Metal‐Amides

Reponen

Chotard

Lempelto

et al. 2022

Advanced Optical Materials

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“…The difference between the geometry of the ground and excited state needs to be considered to realize efficient phosphorescence from Carbene-M(I)-Halides. The series of copper complexes (CAAC)Cu(X) (X = Cl, Br, I) show phosphorescence in the solid state with PLQY up to 96%, whereas gold analogues (CAAC)Au(X) (X = Cl, Br, I) suffer from low PLQY values up to 18%. Theoretical calculation results explain that this due to significant deviation from linearity around metal center.…”

Section: Resultsmentioning

confidence: 99%

Linear Gold(I) Halide Complexes with a Diamidocarbene Ligand: Synthesis, Reactivity, and Phosphorescence

Riley,

Phuoc,

Linnolahti

et al. 2023

Organometallics

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A series of halide and pseudohalide gold complexes (DAC)Au(I)X (DAC = N,N′-diamidocarbene; X = Cl, Br, I, and SCN) were prepared in high yields. All complexes possess linear geometry around the gold atom with no aurophilic interactions between neighboring molecules. Reactivity studies for (DAC)Au(I)-Cl revealed that the diamido backbone of the carbene ligand is vulnerable to nucleophilic attack by a strong base, potassium tertbutoxide, resulting in cleavage of the carbene backbone and formation of a neutral trigold cluster. Halide and pseudohalide complexes are bright phosphorescent emitters in the solid state, exhibiting photoluminescence quantum yields up to unity. Phosphorescence occurs in the range 480−520 nm with lifetimes as short as 1 μs, resulting in fast radiative rates up to 9.4 × 10 5 s −1 which is on par with the most efficient heavy metal emitters. Photophysical properties are explained by the intrinsic π-accepting nature of the DAC carbene and are supported by TDDFT calculations.

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“…Carbene-metal-amido complexes bearing cyclic alkyl amino carbene (CAAC) ligands have recently emerged as a new class of highly efficient light-emitting materials. [109] In many cases, their luminescence is ascribed to thermally activated delayed fluorescence (TADF) due to ligand-toligand charge transfer (LLCT) involving electron donation from the electron-rich amido ligand to a LUMO, based on the carbene p orbital, which acts as π-acceptor. Because of the small energy separation between the lowest singlet and triplet excited states, the intersystem crossing from the longlived triplet to the faster radiating singlet state is facilitated.…”

Section: [Au(nhc)(amido)] Complexesmentioning

confidence: 99%

Gold(I)‐N‐Heterocyclic Carbene Synthons in Organometallic Synthesis

Scattolin

Tonon

Botter

et al. 2023

Chemistry A European J

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The prominent role of gold‐N‐heterocyclic carbene (NHC) complexes in numerous research areas such as homogeneous (photo)catalysis, medicinal chemistry and materials science has prompted organometallic chemists to design gold‐based synthons that permit access to target complexes through simple synthetic steps under mild conditions. In this review, the main gold‐NHC synthons employed in organometallic synthesis are discussed. Mechanistic aspects involved in their synthesis and reactivity as well as applications of gold‐NHC synthons as efficient pre‐catalysts, antitumor agents and/or photo‐emissive materials are presented.

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Synthesis and photophysical properties of linear gold(i) complexes based on a CCC carbene

Abstract: New gold carbazolate complexes based on a CCC-type carbene ligand give red photoemitters with sub-microsecond excited state lifetimes.

Cited by 8 publications

References 36 publications

Donor N‐Substitution as Design Principle for Fast and Blue Luminescence in Carbene‐Metal‐Amides

Donor N‐Substitution as Design Principle for Fast and Blue Luminescence in Carbene‐Metal‐Amides

Linear Gold(I) Halide Complexes with a Diamidocarbene Ligand: Synthesis, Reactivity, and Phosphorescence

Gold(I)‐N‐Heterocyclic Carbene Synthons in Organometallic Synthesis

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