Surface-Active Mononuclear and Dinuclear Ru(II) Complexes based on Thio-substituted Terpyridines Bearing Cyclodextrin Recognition Units

Abstract

Ruthenium(II) surface active complexes based on a tpySH ligand have been prepared and characterised, (1) [Ru(tpyada)(tpySH)](PF₆)₂, (2) [Ru(biptpy)(tpySH)](PF₆)₂ and (3) [Ru(pm-β-CD(ttp))(tpySH)](PF₆)₂. The complexes bear a surface active thiol group and a recognition unit which is either a β-cyclodextrin or a hydrophobic tail (adamantyl- or biphenyl) in order to utilise cyclodextrin recognition for the formation of supramolecular wires using bottom up approaches. Monolayers of [Ru(tpyada)(tpySH)](PF₆)₂ on ITO surfaces are studied by electrochemical techniques. Detailed NMR analysis of tpySH reveals the presence of two tautomers, an “NH” and an “SH” form. The X-ray crystal structure of the oxidised form of the ligand tpySStpy is reported. A new ligand tpySCH₂Stpy is prepared and its dinuclear Ru(II) complexes are reported, (4) [(ttp)Ru(tpyS CH₂Stpy)Ru(ttp)]⁺², (5) [(biptpy)Ru(tpySCH₂Stpy)Ru(bitpy)]⁺², (6) [(pm-β-CD(ttp))Ru(tpySCH₂ Stpy)Ru(pm-β-CD(ttp))]⁺². The complexes show characteristic red ³MLCT luminescence which is much stronger than their analogous mononuclear counterparts.

Keywords:

• Surface active metal complexes
• Cyclodextrin
• electrochemistry
• Luminescence

Acknowledgements

Financial support from the Marie Curie Research Training Network grant “UNI-NANOCUPS” (MRTN-CT-2003-504233) is appreciated. P.B greatly acknowledges support via a Marie Curie Intra-European Fellowship (MEIF-CT-2005-515356) under the 6^th European Community Framework Programme. We also wish to acknowledge COST-D31 action and the Aventis Foundation for support (MJJPS).