Inorganic mesoporous silicas as vehicles of two novel anthracene-based ruthenium metalloarenes

Abstract

Two novel anthracene-based half-sandwich organometallic Ru(II) compounds, namely, [Ru(p-cymene)(L1)Cl2] (1) and [Ru(p-cymene)(L2)Cl2] (2) (L1 = 1-(anthracen-9-yl)-N-(pyridin-3-ylmethyl)methanamine; L2 = 1-(anthracen-9-yl)-N-(pyridin-4-ylmethyl)methanamine) have been synthesized and characterized. We demonstrate that the fluorescence properties of these complexes are highly affected by the linking position of the anthracene unit, as only 2 shows fluorescence emission in the blue region. Regarding their biological activity, both ruthenium metallodrugs show interaction with different biological targets such as S-donor amino acids (cysteine) and proteases (cysteine cathepsin B). Moreover, 1 and 2 show in vitro cytotoxicity against HL-60 cancer cell line (IC50 = 84.5 and 87.0 μM for 1 and 2, respectively), with cell death occurring via apoptosis. Further studies have shown that diffusion into cells is the main mechanism of metallodrug uptake. Finally, as a proof of concept, these ruthenium complexes have been successfully encapsulated into MCM-41 and SBA-15 mesoporous silicas using two different incorporation strategies (impregnation and grinding).