
Similarities and differences in d6 low-spin ruthenium, rhodium and iridium half-sandwich complexes: synthesis, structure, cytotoxicity and interaction with biological targets
Author(s) -
Agnieszka Gilewska,
Barbara Barszcz,
Joanna Masternak,
Katarzyna Kazimierczuk,
Jerzy Sitkowski,
Joanna Wietrzyk,
Eliza Turlej
Publication year - 2019
Publication title -
jbic. journal of biological inorganic chemistry/jbic, journal of biological and inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.802
H-Index - 101
eISSN - 1432-1327
pISSN - 0949-8257
DOI - 10.1007/s00775-019-01665-2
Subject(s) - chemistry , ruthenium , rhodium , denticity , iridium , circular dichroism , stereochemistry , chirality (physics) , proton nmr , crystallography , metal , medicinal chemistry , organic chemistry , nambu–jona lasinio model , chiral symmetry breaking , physics , quantum mechanics , quark , catalysis
In this paper, we discussed the similarities and differences in d 6 low-spin half-sandwich ruthenium, rhodium and iridium complexes containing 2,2'-biimidazole (H 2 biim). Three new complexes, {[RuCl(H 2 biim)(η 6 -p-cymene)]PF 6 } 2 ·H 2 O (1), [(η 5 -Cp)RhCl(H 2 biim)]PF 6 (2), and [(η 5 -Cp)IrCl(H 2 biim)]PF 6 (3), were fully characterized by CHN, X-ray diffraction analysis, UV-Vis, FTIR, and 1 H, 13 C and 15 N NMR spectroscopies. The complexes exhibit a typical pseudooctahedral piano-stool geometry, in which the aromatic arene ring (p-cymene or Cp) forms the seat, while the bidentate 2,2'-biimidazole and chloride ion form the three legs of the piano stool. Moreover, the cytotoxic activities of the compounds were examined in the LoVo, HL-60, MV-4-11, MCF-7 human cancer cell lines and BALB/3T3 normal mouse fibroblasts. Notably, the investigated complexes showed no cytotoxic effects towards the normal BALB/3T3 cell line compared to cisplatin, which has an IC 50 value of 2.20 µg. Importantly, 1 displayed the highest activity against HL-60 (IC 50 4.35 µg). To predict a binding mode, we explored the potential interactions of the metal complexes with CT-DNA and protein using UV absorption and circular dichroism. The obtained data suggest that the complexes could interact with CT-DNA via an outside binding mode. Moreover, binding of the complexes with the GSH via UV-Vis and ESI mass spectra was determined. Comparative studies have shown that the rhodium complex (2) is the most GSH reactive, which is probably responsible for its deactivation towards LoVo and MCF-7 tumour cells. The influence of the metal ion on the biological activity of isostructural Rh(III) and Ir(III) complexes was an important goal of the presented investigation.