The redox-functionalised diimine ligand 3,8-di-n-pentyl-4,7-di(ferrocenylethinyl)-1,10-phenanthroline (3) was synthesised and used for the preparation of the homoleptic zinc complex [Zn(3)(2)][PF6](2), whose cyclic voltammogram shows non-interacting ferrocenyl units, affording the hexacationic [Zn(3)(2)](6+) in a four-electron oxidation. (c) 2005 Elsevier B.V. All rights reserved.

The new diimine ligand 3,8- di- n- pentyl- 4,7- di( phenylethynyl)- 1,10- phenanthroline ( 1) was used for the synthesis of a range of PtII complexes, viz. [ Pt( 1) Cl-2], [ Pt( 1)C C - Ph)(2)], [ Pt( 1)( C C - Fc)(2)] and [ Pt( 1)( C C - p- C6H4- C C - Fc)(2)] ( Fc = ferrocenyl). Crystal structure analyses were performed for [ Pt( 1) Cl-2] and [ Pt( 1)( C C - Ph)(2)] and revealed that the di( acetylide) pi- tweezer of the latter binds a molecule of chloroform through C - H (...) pi hydrogen bonds. The redox and optical properties of 1 and its complexes were investigated by ( spectro-) electrochemistry, UV - Vis and luminescence spectroscopy, and an energy level diagram was derived for [ Pt( 1)( C C - Fc)(2)] and related compounds on the basis of the data collected. The ferrocenyl- substituted PtII complexes are donor - sensitiser assemblies. Intramolecular quenching of the photoexcited PtII diimine unit leads to very short luminescence lifetimes for [ Pt( 1)( C C - p- C6H4 - C C - Fc)(2)] ( 2 ns) and [ Pt( 1)( C C - Fc)(2)] ( 0.3 ns), as opposed to [ Pt( 1)( C C - Ph)(2)] ( 0.7 mu s). Excimer formation has been observed for [ Pt( 1)( C C - Ph)(2)] at room temperature in dichloromethane and at low temperatures in frozen glassy dichloromethane and 2- methyltetrahydrofuran solution, but not in the solid state.