Naphthoquinones of natural origin: Aqueous chemistry and coordination to half-sandwich organometallic cations

Abstract

Half-sandwich organometallic complexes featuring Ru(II), Os(II) and Rh(III) metal centers and naturally occurring bidentate 2-hydroxy-[1,4]-naphthoquinone ligands (lawsone and phthiocol) have been synthesized and characterized in both solid state and solution phase by analytical, spectroscopic, electrochemical and single crystal X-ray diffraction techniques. Comparative studies revealed the influence of the respective metal center (Ru, Os, Rh), leaving group (Cl, Br, I) and arene (p-cymene, toluene, pentamethylcyclopentadienyl), as well as the naphthoquinone ligand on the structural properties and solution speciation. Additionally, cytotoxicity was tested in SW480, CH1/PA-1 and A549 human cancer cell lines showing a broad range of IC 50 values.

Tridentate 3-Substituted Naphthoquinone Ruthenium Arene Complexes: Synthesis, Characterization, Aqueous Behavior, and Theoretical and Biological Studies

“…These findings oppose previous findings of organometallic complexes bearing O , O -chelates ( Figure 4 ). 30 , 32 , 33 Based on these observations, an activation via hydrolysis of the elongated Ru– O 2 bond might be feasible, yielding an aqua complex, which has been reported for ruthenium arene complexes with halido leaving groups. 54 − 56 …”

Metal complexes of a pro-vitamin K3 analog phthiocol (2-hydroxy-3-methylnaphthalene-1,4-dione): synthesis, characterization, and anticancer activity

“…Finally, absorbance was measured at 540 nm using a microtitre plate reader (Spectramax M2, molecular devices, USA). The protocol was adopted from Mészáros et al 32 A total of eleven compounds, including the starting material vitamin K3 (menadione) and the phthiocol ligand, pht , were tested along with metal complexes. Four complexes ( 2 , 3 , 4 , and 5 ) were selected for further detailed studies.…”