Heteroleptic Copper(I) Complexes Prepared from Phenanthroline and Bis-Phosphine Ligands: Understanding their Photophysical Behavior

For most photochemists the archetypal luminescent metal complex is probably [Ru(bpy)3]2+, characterized by charge-transfer orange luminescence and a unique combination of chemical stability, redox and excited-state properties.[1] Early studies on Ru(II) coordination compounds were subsequently extended to other metals such as Os(II), Pd(II), Pt(II) and Rh(III) and, in relatively recent years, to cyclometalated Ir(III) complexes.[2] Widespread diffusion of new technologies based on these luminescent transition metal complexes might be hampered by the prohibitive costs of the metal elements, which are related to their scarcity in the Earth's crust. For this reason, in recent years, attention has grown towards less conventional luminescent metal compounds made from more abundant d10 metal ions, such as Cu(I), Ag(I), Au(I), Zn(II) and Cd(II). Key features of these complexes over compounds made from platinum group elements are (i) the lack of non-emissive low- lying MC levels that would quench the luminescent excited states by thermal equilibration or energy transfer, and (ii) a wider variety of coordination geometries. In this talk we report our most recent progress in the understanding of the photophysical properties of a library of heteroleptic [Cu(NN)(PP)]+ complexes prepared from phenanthroline derivatives (NN) and commercially available bis-phosphine ligands (PP). This work provides a deeper understanding of the stability of these complexes and a full rationalization of their photophysical properties, marking the way for future developments and, possibly, technological implementation of d10 metal complexes.[3,4] [1] A. Barbieri, G. Accorsi and N. Armaroli, Chem. Commun., 2008, 2185-2193. [2] R. D. Costa, E. Ortí, H. J. Bolink, F. Monti, G. Accorsi, and N. Armaroli, Angew. Chem., 2012, 8178-8211. [3] A. Kaeser, M. Mohankumar, J. Mohanraj, F. Monti, M. Holler, J.-J. Cid, O. Moudam, I. Nierengarten, L. Karmazin-Brelot, C. Duhayon , B. Delavaux-Nicot, N. Armaroli and J.-F. Nierengarten, Inorg. Chem., 2013, ASAP: 10.1021/ic4020042. [4] F. Monti, J. Mohanraj, A. Kaeser, M. Mohankumar, M. Holler, J.-J. Cid, O. Moudam, I. Nierengarten, L. Karmazin-Brelot, C. Duhayon , B. Delavaux-Nicot, J.-F. Nierengarten and N. Armaroli, MS in preparation.