Supramolecular adducts of native and permethylated β-cyclodextrins with (2,2′-dipyridylamine)chlorido(1,4,7-trithiacyclononane)ruthenium(II) chloride: solid-state and biological activity studies

The complex [([9]aneS3)RuII(dipa)Cl]Cl (1, where dipa = 2,2′-dipyridylamine) was included into native β-cyclodextrin (β-CD) and permethylated β-CD (TRIMEB) by co-dissolution followed by solvent removal. Two adducts were obtained with a 1:1 host:guest stoichiometry. Solid-state studies of the guest comprised collecting the single-crystal structure of its 3.5 hydrate form and also powder diffraction on the remaining bulk material, showing it is isotypical with the harvested crystal for X-ray analysis. Solid-state studies of the cyclodextrin adducts were carried out by powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), 13C{1H} CP/MAS NMR and FTIR spectroscopies. Biological studies on 1 and its adducts comprised the evaluation of the shift caused by 1 on the melting temperature of DNA (ΔT m), as well as the evaluation of cytotoxicity by the MTT assay on the osteosarcoma MG-63 cell line.