We report on the investigation of a new series of symmetric trinuclear ruthenium complexes combined with azanaphthalene ligands: [RuO(CHCOO)(L)]PF where L = (1) quinazoline (qui), (2) 5-nitroisoquinoline (5-nitroiq), (3) 5-bromoisoquinoline (5-briq), (4) isoquinoline (iq), (5) 5-aminoisoquinoline (5-amiq), and (6) 5,6,7,8-tetrahydroisoquinoline (thiq). The crystal structure of complex 1, [RuO(CHCOO)(qui)]PF, was determined by X-ray diffraction analysis, showing a high degree of co-planarity between the [RuO] plane and the azanaphthalene ligands. Spectroscopic (UV-visible, NMR and infra-red) and electrochemical (cyclic voltammetry and spectroelectrochemistry) data showed correlation with the pK values of the azanaphthalene ligands and this dependence was rationalized in terms of the molecular orbital of the [RuO] unit and the structure of the ligands. By analysing the spectroscopic and electrochemical correlations, the ability of the azanaphthalene ligands to extend the electronic π-system of the [RuO] unit to the periphery of the compounds was demonstrated. This electronic effect accounts for the planarity of the structure of complex 1. It was also shown through molecular modeling results that, to explain the spectroscopic and electrochemical behaviour of these species, it is not possible to neglect the electronic mixing between the metallic and the acetate orbitals. Finally, this work revealed that electronic coupling is more pronounced in the azanaphthalene series of complexes than in pyridinic analogues and it is this coupling that determines the spectroscopic and electrochemical behaviour of the new species.
Trinuclear ruthenium complexes with orthometalated phenazines of general formula [Ru3(μ3-O)(μ2-OAc)5(L)(py)2]PF6 (L = dppn, benzo[i]dipyrido[3,2-a:2′,3′-c]phenazine, 1; dppz, dipyrido[3,2-a:2',3'-c]phenazine, 2; CH3-dppz, 7-methyldipyrido[3,2-a:2',3'-c]phenazine, 3; Cl-dppz, 7-chlorodipyrido[3,2-a:2',3'-c]phenazine, 4) were investigated for their cytotoxic activity...
Chagas disease remains a serious
public health concern with unsatisfactory
treatment outcomes due to strain-specific drug resistance and various
side effects. To identify new therapeutic drugs against Trypanosoma
cruzi, we evaluated both the in vitro and in vivo activity of the organometallic gold(III) complex
[Au(III)(Hdamp)(L14)]Cl (L1 = SNS-donating
thiosemicarbazone), henceforth denoted 4-Cl. Our results demonstrated
that 4-Cl was more effective than benznidazole (Bz) in eliminating
both the extracellular trypomastigote and intracellular amastigote
forms of the parasite without cytotoxic effects on mammalian cells.
In in vivo assays, 4-Cl in PBS solution loses the
protonation and becomes the 4-neutral. 4-Neutral reduced parasitaemia
and tissue parasitism in addition to protecting the liver and heart
from tissue damage at 2.8 mg/kg/day. All these changes resulted in
the survival of 100% of the mice treated with the gold complex during
the acute phase. Analyzing the surviving animals of the acute infection,
the parasite load after 150 days of infection was equivalent to those
treated with the standard dose of Bz without demonstrating the hepatotoxicity
of the latter. In addition, we identified a modulation of interferon
gamma (IFN-γ) levels that may be targeting the disease’s
positive outcome. To the best of our knowledge, this is the first
gold organometallic study that shows promise in an in vivo experimental model against Chagas disease.
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