Issue 27, 2021

Osmium(ii) tethered half-sandwich complexes: pH-dependent aqueous speciation and transfer hydrogenation in cells

Abstract

Aquation is often acknowledged as a necessary step for metallodrug activity inside the cell. Hemilabile ligands can be used for reversible metallodrug activation. We report a new family of osmium(II) arene complexes of formula [Os(η6-C6H5(CH2)3OH)(XY)Cl]+/0 (1–13) bearing the hemilabile η6-bound arene 3-phenylpropanol, where XY is a neutral N,N or an anionic N,O bidentate chelating ligand. Os–Cl bond cleavage in water leads to the formation of the hydroxido/aqua adduct, Os–OH(H). In spite of being considered inert, the hydroxido adduct unexpectedly triggers rapid tether ring formation by attachment of the pendant alcohol–oxygen to the osmium centre, resulting in the alkoxy tethered complex [Os(η6-arene-O1)(XY)]n+. Complexes 1C–13C of formula [Os(η61-C6H5(CH2)3OH/O)(XY)]+ are fully characterised, including the X-ray structure of cation 3C. Tether-ring formation is reversible and pH dependent. Osmium complexes bearing picolinate N,O-chelates (9–12) catalyse the hydrogenation of pyruvate to lactate. Intracellular lactate production upon co-incubation of complex 11 (XY = 4-Me-picolinate) with formate has been quantified inside MDA-MB-231 and MCF7 breast cancer cells. The tether Os–arene complexes presented here can be exploited for the intracellular conversion of metabolites that are essential in the intricate metabolism of the cancer cell.

Graphical abstract: Osmium(ii) tethered half-sandwich complexes: pH-dependent aqueous speciation and transfer hydrogenation in cells

Supplementary files

Article information

Article type
Edge Article
Submitted
07 4 2021
Accepted
09 6 2021
First published
10 6 2021
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2021,12, 9287-9297

Osmium(II) tethered half-sandwich complexes: pH-dependent aqueous speciation and transfer hydrogenation in cells

S. Infante-Tadeo, V. Rodríguez-Fanjul, A. Habtemariam and A. M. Pizarro, Chem. Sci., 2021, 12, 9287 DOI: 10.1039/D1SC01939B

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