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

We report the first example of a charge-neutral linear two-coordinate copper(I) complex bearing a sterically demanding acenaphthoimidazolylidene-based N-heterocyclic carbene (NHC) ligand. The identity and geometry of the complex are confirmed by single-crystal X-ray diffraction (XRD) analysis. The complex is poorly emissive at room temperature, showing either ligand-centered (LC) emission around 340 nm when excited at 300 nm or ligand-to-ligand charge transfer (LLCT) emission at 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.