Mono- And Dinuclear Coinage Metal Complexes Supported by an Imino-Pyridine-NHC Ligand: Structural and Photophysical Studies

A new imino-pyridine-NHC (NHC = N-heterocyclic carbene) hybrid ligand was accessed through a multistep synthesis, and its coordination chemistry was examined among coinage metals. Mononuclear copper, silver, and gold complexes as well as dinuclear homo- and heterometallic complexes were isolated and fully characterized by spectroscopic methods as well as X-ray crystallography. A comparative study of the structural and photophysical properties of the complexes was performed to get more insight into structure-property relationships. The photoluminescence (PL) properties were investigated in the solid state at temperatures between 20 and 295 K, and systematically compared with those of related complexes bearing a bipyridine-NHC ligand and previously reported by our group. The PL properties can be finely "tuned" depending on the coordinated metals, and the weak emission of the complexes can be traced back to the structural flexibility of the imino-pyridine-NHC framework.