Structural Diversity of Copper(I)–N‐Heterocyclic Carbene Complexes; Ligand Tuning Facilitates Isolation of the First Structurally Characterised Copper(I)–NHC Containing a Copper(I)–Alkene Interaction

Lake, Benjamin R. M.; Willans, Charlotte E.

doi:10.1002/chem.201301896

Cited by 47 publications

(42 citation statements)

References 48 publications

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“…30 The azolium salts include new picolyl linkers, functionalized in the para position with Cl, Me, OMe and NO 2 . The complexes obtained are related to previously reported analogs, of which no photophysical properties have been described, [31][32][33][34][35] and also form monomeric, dimeric and polymeric structures depending on the picolyl donor strength and/or the crystallization method.…”

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confidence: 55%

Cuprophilic interactions in highly luminescent dicopper(i)–NHC–picolyl complexes – fast phosphorescence or TADF?

et al. 2016

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This case study on a series of monomeric, dimeric and polymeric Cu I chlorido NHC-picolyl complexes shows that cuprophilic interactions can ensure strong spin-orbit coupling for fast (reverse)intersystem-crossing T 1 2 S 1 and T 1 -S 0 , and therefore can serve as a design motif for the construction of highly efficient Cu I -based TADF or T 1 emitters.Luminescent molecules showing thermally activated delayed fluorescence (TADF), i.e. thermally induced reverse intersystemcrossing (RISC) T 1 -S 1 with subsequent emission from the singlet excited state S 1 -S 0 , have proven to be particularly suitable materials for OLEDs and other photonic applications, as they are able to bypass the spin-forbidden phosphorescence T 1 -S 0 . [1][2][3] In this regard, Cu I complexes with a d 10 configuration have gained a lot of attention in the last 5 years, as the absence of metal centred d-d* transitions, leading to nonradiative decay, in combination with TADF makes them competitive to Ir III -and Pt II -based emitters. [4][5][6][7][8][9][10][11][12][13][14][15][16] Although some structure-property relationships have been formulated, [17][18][19] TADF in copper complexes is still difficult to predict a priori, let alone to design TADF materials, as it is an excited state property. In contrast, cuprophilic interactions can be prearranged in the ground state by careful choice of the ligand environment, and they have been shown to allow, albeit inefficiently, phosphorescence in simple dinuclear Cu I complexes with bridging diphosphines and other systems, 20-23 and also in clusters. [24][25][26] A few dicopper(I) complexes with short Cu-Cu contacts (o2.8 Å) have been reported to emit efficiently via TADF, but the influence of cuprophilic interactions in those has yet not been addressed. 4,8,19,[27][28][29] In this case study on a family of new bidentate copper(I) NHC-picolyl complexes we show that cuprophilic interactions can greatly enhance the radiative rate constants of the T 1 state by increasing spin-orbit coupling (SOC), giving emission lifetimes comparable to TADF, and can even be involved in the luminescence mechanisms when TADF is present. Thus, cuprophilic interactions provide a design methodology for highly efficient Cu I emitters.For this study, we have prepared a series of Cu I NHC-picolyl complexes (1-7, Fig. 1) by a facile one-step silver-free procedure from azolium chlorides in aqueous ammonia as basic and copper complexing medium (see ESI †). 30 The azolium salts include new picolyl linkers, functionalized in the para position Fig. 1 Chemical structures of complexes 1-7, for dimers representative molecular structure of 1 obtained from X-ray diffraction and intermolecular Cu-Cu distances of 1-4.

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confidence: 55%

Cuprophilic interactions in highly luminescent dicopper(i)–NHC–picolyl complexes – fast phosphorescence or TADF?

et al. 2016

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“…To further support these findings, we undertook an experimental study to examine the effect of a mixed-ligand system. Cu I -NHC complex 8 (bearing an allyl substituent) [34] was allowed to react with 2-bromoimidazolium salt 7 (bearing a mesityl substituent) (1:1) in the presence of one equivalent of CuBr (Scheme 4). NMR spectroscopy and mass spectrometry revealed that the resulting product was a mixture of the hetero-coupled bis-imidazolium dimer 9 and, surprisingly, the homo-coupled product 5 (~20:1).…”

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confidence: 99%

Mechanistic Insights into the Oxidative Coupling of N‐Heterocyclic Carbenes within the Coordination Sphere of Copper Complexes

Lake

Ariafard

Willans

2014

Chemistry A European J

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The behavior of N-heterocyclic carbene (NHC) ligands in organometallic chemistry is hugely important for catalysis, due to the effect of these ligands on catalytic pathways and their involvement in catalyst decomposition. In this report, a combined experimental and computational study is presented, which provides mechanistic understanding of the unprecedented oxidative coupling of NHCs at Cu. The presence of Cu(I) -, Cu(II) -, and Cu(III) -NHC complexes during the process is postulated, with the unusual Ccarbene -Ccarbene oxidative coupling reaction occurring under extremely mild reaction conditions. This process may represent a novel pathway for the decomposition of Cu-NHC complexes.

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“…These ligands also represent an interesting scaffold for the synthesis of dinuclear complexes of linear two‐coordinate d 10 group 11 metal ions. For example, the dinuclear Cu I complex II (Figure ) adopts a helical or twisted structure in the solid state with one short Cu I ‐alkene interaction . Similar dinuclear Ag I complexes have been prepared (e.g.…”

Section: Introductionmentioning

confidence: 96%

“…Dinuclear Cu I , Ag I , and Au I complexes bearing cyclophane type bis(N‐heterocyclic carbene) ( I ) and arene‐bridged bidentate NHC ligands ( II – IV ). [7a], , , [14a]…”

Section: Introductionmentioning

confidence: 99%

Probing Conformational Variation in Luminescent Dinuclear Gold(I) N‐Heterocyclic Carbene Complexes

et al. 2017

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A series of six dinuclear AuI complexes bearing arene‐bridged bidentate imidazolylidene (N‐heterocyclic carbene, NHC) ligands have been synthesized and characterized. The ligand arene linkers (benzene, pyridine, pyrazine) and NHC‐wingtip R‐groups (methyl, benzyl) were modified to investigate the influence of these groups on the preference for two distinct conformational isomeric forms. These two conformations differ in their Au···Au distances; an open form with an Au···Au separation of ca. 7 Å and a twisted conformation with a short Au···Au distance of ca. 3 Å. Five of the complexes were structurally characterized using X‐ray crystallography. Photophysical studies on the complex with a pyridyl linker group and benzyl wingtip groups showed that the twisted conformation resulted in a low‐energy (LE) photoluminescence emission that is associated with the intermolecular aurophilic interaction. In contrast, no room temperature (r.t.) photoluminescence was observed for the open conformation in the solid state, while a high‐energy (HE) emission was observed at 77 K. The pyridyl linked complexes were non‐emissive in solution at room temp., but upon freezing to form a glassy matrix at 77 K, dual HE and LE emissions were observed that closely match the solid‐state spectra for open and twisted complexes, respectively. These observations, in combination with a thorough theoretical investigation, provide important insights into the conformational behavior of complexes of this type. The use of low temperature frozen glasses to trap individual components of conformationally diverse samples for photoluminescence investigations represents a novel approach to study the dynamic and conformational behavior of dinuclear AuI complexes in solution.

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Structural Diversity of Copper(I)–N‐Heterocyclic Carbene Complexes; Ligand Tuning Facilitates Isolation of the First Structurally Characterised Copper(I)–NHC Containing a Copper(I)–Alkene Interaction

Abstract: The preparation of a series of imidazolium salts bearing N-allyl substituents, and a range of substituents on the second nitrogen atom with varying electronic and steric properties, is reported.

Cited by 47 publications

References 48 publications

Cuprophilic interactions in highly luminescent dicopper(i)–NHC–picolyl complexes – fast phosphorescence or TADF?

Cuprophilic interactions in highly luminescent dicopper(i)–NHC–picolyl complexes – fast phosphorescence or TADF?

Mechanistic Insights into the Oxidative Coupling of N‐Heterocyclic Carbenes within the Coordination Sphere of Copper Complexes

Probing Conformational Variation in Luminescent Dinuclear Gold(I) N‐Heterocyclic Carbene Complexes

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