Interactions of (η5-CpRu)-[12]cycloparaphenylene full-sandwich complexes with 9-methylguanine

The synthesis and the characterization of (RuCp)-[12]CycloParaPhenylene complexes of the general formula [([12]CPP)(RuCp)n](PF6)n (n = 1–3, 4–6 and 9–12) was achieved by the reaction of [(η5-Cp)Ru(CH3CN)3](PF6) with [12]CPP in dry acetone. The number n of the (RuCp) substitutions on [12]CPP varied depending on the reaction molar ratio, producing mixtures with average (RuCp) moieties, ω1:1 = 2.9, ω1:6 = 4.9, ω1:12 = 10, which were analyzed by 1H NMR spectroscopy and high-resolution ESI mass spectrometry. The [([12]CPP)(RuCp)n]Cln (n = 4–6) was transformed to its corresponding [Cl]− salt which was stable in aqueous solution in the dark, but released (RuCp) solvolyzed species upon UV (365 nm) irradiation. The addition of 9-MeG in an aqueous solution containing [([12]CPP)(RuCp)n]Cln (n = 4–6) which was subsequently irradiated with UV (365 nm) formed adducts between the released (RuCp) and the 9-MeG, where 9-MeG was coordinated through N7. This may be useful in the application of full-sandwich ruthenium-arene complexes in cancer photodynamic therapy.