Physical and photophysical properties of a linear copper(I) complex of a bulky acenapthene-based NHC ligand

Abstract

We report the first example of a charge-neutral linear 2-coordinate copper(I) complex bearing a sterically demanding acenaphthoimidazolylidene-based N-heterocyclic carbene ligand. The identity and geometry of the complex was confirmed by single-crystal XRD (X-Ray Diffraction) analysis. The complex is poorly emissive at room temperature, showing either ligand-centered (LC) emission at around 340 nm when excited at 300 nm or ligand-to-ligand charge-transfer (LLCT) emission at around 540 nm when excited at 420 nm; in chloroform, dual emission is observed upon photoexcitation at 300 nm. Nanosecond emission lifetimes were recorded for these processes. This is the first example of emissive linear copper(I) complexes containing this bulky NHC ligand.

Synthesis of Carbene‐Metal‐Amido (CMA) Complexes and Their Use as Precatalysts for the Activator‐Free, Gold‐Catalyzed Addition of Carboxylic Acids to Alkynes

“…[Cu(BIAN‐IPr)Cl] was also subjected to the protocol, and the expected copper complex was obtained at a lower temperature (40 °C) than the corresponding gold congener (Table 1, entry 9). It should be noted that [Cu(BIAN‐IPr)(Cbz)] ( 2 a ) has been reported recently and was obtained in moderate yield but through the use of a strong base (NaOH) and a phase transfer catalyst [22] . The present method renders its synthesis operationally simpler, accessing CMAs based on copper and backbone‐modified NHC ligands much more efficiently.…”

“…It should be noted that [Cu(BIAN-IPr)(Cbz)] (2 a) has been reported recently and was obtained in moderate yield but through the use of a strong base (NaOH) and a phase transfer catalyst. [22] The present method renders its synthesis operationally simpler, accessing CMAs based on copper and backbonemodified NHC ligands much more efficiently.…”

“…[21,24,25] Additionally, a linear Cu I complex, [Cu(BIAN-IPr)(Cbz)], bearing a bulky acenaphthoimidazolylidene-based N-heterocyclic carbene has been reported to exhibit interesting emissive properties. [22] All the above protocols have significant limitations such as the requirement of inert atmosphere, the need for expensive, strong bases, the use of additives or multistep procedures and toxic solvents. Recently, an operationally simple synthetic protocol for the synthesis of N-heterocyclic carbene coinage metal-amido complexes and its extension to continuous flow synthesis have been reported.…”

A Green Synthesis of Carbene‐Metal‐Amides (CMAs) and Carboline‐Derived CMAs with Potentin vitroandex vivoAnticancer Activity

“…The carbene ligand is usually a cyclic (alkyl)(amino) carbene or monoamido-(MAC) or diamido-carbene DAC), [4][5][6][7][8][9][10][11][12][13][14][15] and less often a (benz)imidazolylidene or mesoionic carbene. [16][17][18][19][20][21][22][23] The ligand combination in the former case renders these materials ideal for Thermally Activated Delayed Fluorescence (TADF) applications. The latter cases have received comparatively much less attention because of limited potential for OLED materials applications, even though recent advances show that modifications of the acceptor imidazol(in)ylidene ligand enable throughspace TADF.…”

“…The latter cases have received comparatively much less attention because of limited potential for OLED materials applications, even though recent advances show that modifications of the acceptor imidazol(in)ylidene ligand enable through‐space TADF [24] . Importantly, applications beyond TADF are possible when using imidazol(in)ylidene‐based CMAs, with recent examples being long‐lived room temperature phosphorescence (RTP), [18] and photocatalysis by triplet energy transfer [22] . For the latter application, the choice of the carbene ligand and the metal, Au in particular, is paramount as weaker π ‐acceptors enable longer‐lived triplet states and the strong spin‐orbit coupling (SOC) of the heavy metal atom enables efficient intersystem crossing (ISC), thus these compounds emit solely via phosphorescence, in addition to being more photolytically stable than their Ag congeners.…”