JBIC Journal of Biological Inorganic Chemistry (2018) 23:763–774
Impact of various lipophilic substituents on ruthenium(II), rhodium(III)
and iridium(III) salicylaldimine‑based complexes: synthesis, in vitro
cytotoxicity studies and DNA interactions
· Tameryn Stringer
· Alan T. Hutton
· Sharon Prince
· Gregory S. Smith
Received: 14 March 2018 / Accepted: 28 April 2018 / Published online: 30 May 2018
© SBIC 2018
A series of bidentate salicylaldimine ligands was prepared and reacted with either [RuCl(µ-Cl)(p-cymene)]
. All of the compounds were characterised using an array of spectroscopic and analytical
techniques, namely, nuclear magnetic resonance (NMR) spectroscopy, infrared (IR) spectroscopy and mass spectrometry.
Single crystal X-ray diﬀraction (XRD) was used to conﬁrm the bidentate coordination mode of the salicylaldimine ligand
to the metal centre. The platinum group metal (PGM) complexes were screened against the MCF7 breast cancer cell line.
The ruthenium and iridium salicylaldimine complexes showed comparable or greater cytotoxicity than cisplatin against the
MCF7 cancer cells, as well as greater cytotoxicity than their rhodium counterparts. Three of the salicylaldimine complexes
showed potent activity in the range 18–21 µM. Two of these complexes had a greater aﬃnity for cancerous cells than for
CHO non-cancerous cells (SI > 4). Preliminarymechanistic studies suggest that the ruthenium complexes undergo solvation
prior to 5′-GMP binding, whereas the iridium complexes were inert to the solvation process.
Crystallographic data: CCDC 1572708 (11), CCDC 1572709 (12),
CCDC 1572710 (13).
* Gregory S. Smith
Department of Chemistry, University of Cape Town,
Rondebosch 7701, South Africa
Department of Human Biology, University of Cape Town,
Medical School, Observatory 7925, South Africa