Enhancement of Cytotoxicity by Combining Pyrenyl-Dendrimers and Arene Ruthenium Metallacages

Three generations of pyrenyl bis-MPA dendrimers with two different end-groups, acetonide (pyr_Gn) or alcohol (pyr_Gn-OH) (<i>n</i> = 1–3), were synthesized, and the pyrenyl group of the dendritic molecules was encapsulated in the arene ruthenium metallacages, [Ru₆(<i>p</i>-cymene) ₆ (OO∩OO)₃(tpt)₂]⁶⁺ (OO∩OO = 5,8-dioxydo- 1,4-naphtaquinonato (donq) [1]⁶⁺ and 6,11-dioxydo-5,12- naphtacenedionato (dotq) [2]⁶⁺; tpt =2,4,6-tri(pyridin-4-yl)-1,3,5-triazine). The host–guest properties of [guestC1]⁶⁺ and [guestC2]⁶⁺ were studied in solution by NMR and UV–vis spectroscopic methods, thus allowing the determination of the affinity constants. Moreover, the cytotoxicity of these water- soluble host–guest systems and the pyrenyl-dendrimers was evaluated on human ovarian cancer cells.