Neutral and cationic osmium(II)-arene metallodendrimers: Synthesis, characterisation and anticancer activity

Two neutral and two cationic half-sandwich Os(II)-arene metallodendrimers, of general formula [DAB-PPI-{(η6-p-cym)Os((C7H5NO)-κ2-N,O)Cl}n] and [DAB-PPI-{(η6-p-cym)Os((C6H5N2)-κ2-N,N)Cl}n][PF6]n (where n = 4 (G1) or 8 (G2)) have been synthesised. In addition, two cationic half-sandwich Os(II)-arene metallodendrimers, containing PTA (1,3,5-triaza-7-phosphatricyclo[3.3.1.1.] decane), of general formula [DAB-PPI-{(η6-p-cym)Os((C7H5NO)-κ2-N,O)PTA}n][PF6]n are also reported. All complexes have been characterised using analytical (i.e. HR-ESI or EI mass spectrometry and elemental analysis) and spectroscopic (i.e. 1H, 13C{1H} NMR and infrared) methods. Model mononuclear analogues have been prepared and their molecular structures determined by single-crystal X-ray crystallography. The cytotoxicity of the complexes were evaluated against the A2780 and A2780cisR human ovarian carcinoma cell lines and some display moderate activity.