Transition metal complexes of Ru(II), Os(II) or Ir(III) exhibit exeptional properties and enable various light-driven processes. But they suffer from limited photophysical activity due to decreased extinction coefficients at higher wavelengths (after 500 nm) and relatively small excited-state (ES) lifetimes. The multichromophoric approach is one possibility to overcome those drawbacks. Usage of additional, organic chromophores should enable us to use a wide range of the solar spectrum and extend the ES lifetimes. As a novel rylene type dye a diimine ligand with a fully rigid and extended π-system in its backbone was prepared by directly fusing a 1,10-phenanthroline building block with 1,8-naphthalimide. The corresponding heteroleptic ruthenium photosensitizer was synthesized and extensively analyzed by a combination of NMR, single crystal X-ray diffraction, steady-state absorption and emission, time-resolved spectroscopy and different electrochemical measurements supported by time-dependent density functional theory calculations.

[1] A. Juris, V. Balzani, F: Barigeletti, S. Campagna, P. Belser, A. von Zelewsky Coord. Chem. Rev. 1988, 84, 85-277; [2] A. Lavie-Cambot, C. Lincheneau, M. Cantuel, Y. Leydet, N. D. McClenaghan Chem. Soc. Rev. 2010, 39 (2), 506–515; [3] H. Langhals Heterocycles 1995, 40 (1), 477–500; [4] Y. Yang, J. Brückmann, W. Frey, S. Rau, M. Karnahl, S. Tschierlei Chemistry - A European Journal 2020, accepted.