Synthesis, structures and photoluminescence properties of silver complexes of cyclic (alkyl)(amino)carbenes

Romanov, Alexander S.; Bochmann, Manfred

doi:10.1016/j.jorganchem.2017.02.045

Cited by 33 publications

(33 citation statements)

References 46 publications

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“…Coinage metal complexes are noted for their ability to emit light by phosphorescence or thermally activated delayed fluorescence (TADF) mechanisms . We have recently reported the synthesis and properties of photoemissive complexes of the type (CAAC)MX (M = Cu, Ag, Au; X = halide, aryloxide or amide; CAAC = cyclic alkyl(amino) carbene), with amide complexes (X = NPh 2 or carbazolate) being particularly effective . In these linear compounds, the metal links CAAC carbene ligands with carbazolate (Cz) anions to give a rotationally flexible donor–metal–acceptor type structure.…”

Section: Comparison Of Bond Distances [å] and Angles [°] Of The Isostmentioning

confidence: 99%

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Mononuclear Silver Complexes for Efficient Solution and Vacuum‐Processed OLEDs

Romanov

Jones

Yang

et al. 2018

Advanced Optical Materials

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on mononuclear silver. [7] Indeed, OLED devices based on 2nd row metals in general are remarkably rare and characterized by low efficiency. [8] Here, we report silver complexes with sub-microsecond radiative triplet lifetimes and high performance in both solution and vacuum-deposited OLED devices.Complexes 1 and 2 were readily obtained from ( Ad L)AgCl [3] and carbazole/NaO t Bu as off-white (1) or yellow (2) solids (Figure 1). The compounds are stable for long periods of time both in air and in solution in nonprotic organic solvents. Unlike many silver complexes, they are not sensitive to ambient light. Thermogravimetric analysis gives decomposition temperatures (5% weight loss) of 264.8 (1) and 263.6 °C (2). The observation of the 13 C(carbene) NMR signal (δ C 263) as two sharp 13 C 109 Ag and 13 C 107 Ag coupled doublets (J AgC = 219 and 189 Hz, respectively) confirmed that the complexes do not undergo carbene ligand exchange. [9] Single crystal X-ray diffraction of 1 and 2 confirmed the mononuclear two-coordinate geometry and the absence of significant intermolecular contacts. The C1(CAAC)···N2(Cz) distance is of prime importance since it is directly related to the highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) overlap, which impacts on the radiative rate and exchange energy of (carbene)metal amides; this distance is slightly longer for 1 (4.152 Å) than for 2 (4.125 Å).Both 1 and 2 show a quasi-reversible one-electron metalcentered reduction process (tetrahydrofuran (THF) solution, [ n Bu 4 N]PF 6 as supporting electrolyte; Figures S2 and S3 and Table S1, Supporting Information). The estimated LUMO energies (1: −2.86 eV; 2: −2.83 eV) compare well with those for the Au (−2.79 eV) and Cu analogs (−2.66 eV) [5] and are only marginally affected by the nature of the metal. The peak-to-peak separation ΔE p is smaller for 2 (124 mV) than for 1 (185 mV), indicating higher stability of the reduced species of 2, potentially making it a more robust emitter under electrical excitation. The HOMO levels based on the onset of the first oxidation potentials are at −5.51 and −5.29 eV for 1 and 2, respectively. These values guide the identification of host materials for OLED fabrication. [10] The electronic structure of 1 and 2 has been evaluated using density-functional theory (DFT) for the ground state and timedependent DFT (TD-DFT) [11] calculations for the excited states using the MN15 functional by Truhlar and co-workers [12] in combination with def2-TZVP basis set by Ahlrichs and Carbene metal amides are a new class of highly efficient light-emitting molecules based on a linear donor-metal-acceptor geometry. Here the synthesis, structure, and photo-and electroluminescence of carbene silver carbazolato complexes, ( Ad L)Ag(Cz) [ Ad L = adamantyl-substituted cyclic (alkyl)(amino) carbene; Cz = carbazolate (1) and 3,6-t Bu 2 Cz (2)], are reported. They display green emission with photoluminescence quantum yields of up to 74%. Efficient mixing of triplet and singlet excited states is o...

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Section: Comparison Of Bond Distances [å] and Angles [°] Of The Isostmentioning

confidence: 99%

“…Complexes 1 and 2 were readily obtained from ( Ad L)AgCl and carbazole/NaO t Bu as off‐white ( 1 ) or yellow ( 2 ) solids ( Figure ). The compounds are stable for long periods of time both in air and in solution in nonprotic organic solvents.…”

Section: Comparison Of Bond Distances [å] and Angles [°] Of The Isostmentioning

confidence: 99%

Mononuclear Silver Complexes for Efficient Solution and Vacuum‐Processed OLEDs

Romanov

Jones

Yang

et al. 2018

Advanced Optical Materials

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135

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“…23 For these reasons CAAC silver complexes are rather poor carbene transfer agents; for example they failed to give the expected carbene transfer to rhodium and ruthenium targets. 24 These characteristics are however beneficial for biological applications, as further supported by recent results on polycyclic CAAC complexes reported by Waldmann and coworkers. 25 4 outlined in Scheme 1.…”

Section: Introductionmentioning

confidence: 73%

Synthesis, structure and cytotoxicity of cyclic (alkyl)(amino) carbene and acyclic carbene complexes of group 11 metals

et al. 2017

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A series of complexes of cyclic (alkyl)(amino)carbene (CAAC) complexes of copper, silver and gold have been investigated for their antiproliferative properties. A second series of acyclic carbene (ACC) complexes of gold(i) were prepared by nucleophilic attack on isocyanide complexes by amines and amino esters, to give (ACC)AuCl, [(ACC)Au(PTA)] (PTA = triazaphosphaadamantane), as well as mixed-carbene compounds [(CAAC)Au(ACC)]. Representative complexes were characterised by X-ray diffraction which confirmed the mononuclear linear structures without close intermolecular contacts or aurophilic interactions. The redox properties of these complexes have been determined. The compounds were tested against a panel of human cancer cell lines including leukemia (HL 60), breast adenocarcinoma cells (MCF-7) and human lung adenocarcinoma epithelial cell lines (A549), which show varying degrees of cisplatin resistance. The pro-ligand iminium salts and the PTA complexes were non-toxic. By contrast, the CAAC complexes show high cytotoxicity, with IC values in the sub-micromolar to ∼100 nanomolar range, even against cisplatin-insensitive MCF-7 and A549 cells. Cationic bis-carbene complexes [(CAAC)M] (6-8, M = Cu, Ag and Au) proved particularly effective. The mechanism of cell growth control by these complexes remains to be established, although possible modes of action such as inhibition of thioredoxin reductase (TrxR), which is a common pathway for gold NHC compounds, or the formation of reactive oxygen species (ROS) through redox processes, could be ruled out as primary pathways.

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“…Some examples that highlight the importance of CAACs as ligands for coinage metals include unique complexes with metals in their zero valent state . Additionally, Bochmann and others have successfully showed strong photoluminescence behavior of two‐coordinate CAAC/BICAAC/NHC's complexes of Cu(I), Ag(I) and Au(I) . Simple CAAC metal halide complexes (CAAC Ad )MX (M=Cu, Au; X=Cl, Br, I) were also highly photoemissive .…”

Section: Introductionmentioning

confidence: 99%

Two‐Coordinate Cu(I) and Au(I) Complexes Supported by BICAAC and CAAC Ligands

et al. 2020

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Two‐coordinate Cu(I) and Au(I) complexes supported by bicyclic (alkyl)(amino)carbene, [BICAAC‐CuCl] (1), [BICAAC‐CuI] (2), [(BICAAC)2Cu]+[PF6]– (3) and [(BICAAC)2Au]+[AuCl2]– (6) have been synthesized. The reaction of cyclic (alkyl)(amino)carbene, CAACcy with CuCl afforded [CAACcy‐CuCl] (4) and its further reaction with KPF6 gave [(CAACcy)2Cu]+[PF6]– (5). Complexes 1–6 have been characterized by multinuclear NMR, IR and UV‐Vis., spectroscopic method and high‐resolution mass spectrometry (HRMS). Single crystal X‐ray structure of heteroleptic complexes 1 and 4 and homoleptic complexes [(BICAAC)2Cu]+[CuI2]– (2’), 3 and 6 have also been determined. The crystal structure of these complexes confirmed linear two‐coordinate geometry around the metal centers. In the solid‐ state, complexes 1, 2’, 4 and 6 displayed C−H⋯M (M=Cu, Au) and weak non‐covalent C−H⋯X (X=Cl, I) and C−H⋯H−C interactions. Computational calculations correlate well to the experimentally observed geometry and help elucidate the absorption characteristics type of transitions and the frontier orbitals involved in them.

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Synthesis, structures and photoluminescence properties of silver complexes of cyclic (alkyl)(amino)carbenes

Cited by 33 publications

References 46 publications

Mononuclear Silver Complexes for Efficient Solution and Vacuum‐Processed OLEDs

Mononuclear Silver Complexes for Efficient Solution and Vacuum‐Processed OLEDs

Synthesis, structure and cytotoxicity of cyclic (alkyl)(amino) carbene and acyclic carbene complexes of group 11 metals

Two‐Coordinate Cu(I) and Au(I) Complexes Supported by BICAAC and CAAC Ligands

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