Issue 7, 2022

Photocytotoxicity and photoinduced phosphine ligand exchange in a Ru(ii) polypyridyl complex

Abstract

Two new tris-heteroleptic Ru(II) complexes with triphenylphosphine (PPh3) coordination, cis-[Ru(phen)2(PPh3)(CH3CN)]2+ (1a, phen = 1,10-phenanthroline) and cis-[Ru(biq)(phen)(PPh3)(CH3CN)]2+ (2a, biq = 2,2′-biquinoline), were synthesized and characterized for photochemotherapeutic applications. Upon absorption of visible light, 1a exchanges a CH3CN ligand for a solvent water molecule. Surprisingly, the steady-state irradiation of 2a followed by electronic absorption and NMR spectroscopies reveals the photosubstitution of the PPh3 ligand. Phosphine photoinduced ligand exchange with visible light from a Ru(II) polypyridyl complex has not previously been reported, and calculations reveal that it results from a trans-type influence in the excited state. Complexes 1a and 2a are not toxic against the triple negative breast cancer cell line MDA-MB-231 in the dark, but upon irradiation with blue light, the activity of both complexes increases by factors of >4.2 and 5.8, respectively. Experiments with PPh3 alone show that the phototoxicity observed for 2a does not arise from the released phosphine ligand, indicating the role of the photochemically generated ruthenium aqua complex on the biological activity. These complexes represent a new design motif for the selective release of PPh3 and CH3CN for use in photochemotherapy.

Graphical abstract: Photocytotoxicity and photoinduced phosphine ligand exchange in a Ru(ii) polypyridyl complex

Supplementary files

Article information

Article type
Edge Article
Submitted
13 Okt 2021
Accepted
03 Jan 2022
First published
01 Feb 2022
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., 2022,13, 1933-1945

Photocytotoxicity and photoinduced phosphine ligand exchange in a Ru(II) polypyridyl complex

S. J. Steinke, S. Gupta, E. J. Piechota, C. E. Moore, J. J. Kodanko and C. Turro, Chem. Sci., 2022, 13, 1933 DOI: 10.1039/D1SC05647F

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