Luminescent Dinuclear Copper(I) Complexes Bearing an Imidazolylpyrimidine Bridging Ligand

Funding: C.Li thanks the Prof. & Mrs. Purdie Bequests Scholarship and AstraZeneca for a PhD Studentship. We are grateful to the Engineering and Physical Sciences Research Council of the UK (EPSRC) for financial support (grants EP/R035164/1 and EP/P010482/1). We acknowledge the EPSRC UK National Mass Spectrometry Facility at Swansea University for mass spectrometry analysis. The work in Mons was supported by the European Commission / Région Wallonne (FEDER –BIORGEL project), the Consortium des Équipements de Calcul Intensif (CÉCI), funded by the Fonds National de la Recherche Scientifique (F.R.S.-FNRS) under Grant No. 2.5020.11 as well as the Tier-1 supercomputer of the Fédération Wallonie-Bruxelles, infrastructure funded by the Walloon Region under Grant Agreement n1117545, and FRS-FNRS. The synthesis and photophysical study of two dinuclear copper(I) complexes bearing a 2-(1H-imidazol-2-yl)pyrimidine bridging ligand are described. The tetrahedral coordination sphere of each copper center is completed through the use of a bulky bis(phosphine) ligand, either DPEphos or Xantphos. Temperature-dependent photophysical studies demonstrated emission through a combination of phosphorescence and thermally activated delayed fluorescence for both complexes, and an intense emission (ΦPL = 46%) was observed for a crystalline sample of one of the complexes reported. The photophysics of these two complexes is very sensitive to the environment. Two pseudopolymorphs of one of the dinuclear complexes were isolated, with distinct photophysics. The emission color of the crystals can be changed by grinding, and the differences in their photophysics before and after grinding are discussed. Postprint