Osmium(IV) complexes with 1H- and 2H-indazoles: tautomer identity versus spectroscopic properties and antiproliferative activity.
Bottom Line: A one-pot synthesis of osmium(IV) complexes with two different tautomers of indazole, 1H-indazole and 2H-indazole, namely (H(2)ind)[Os(IV)Cl(5)(2H-ind)] (1) and (H(2)ind)[Os(IV)Cl(5)(1H-ind)] (2) is reported.Both compounds have been comprehensively characterized by NMR spectroscopy, ESI (electrospray ionization) mass spectrometry, electronic absorption spectroscopy, IR spectroscopy, cyclic voltammetry and tested for antiproliferative activity in vitro in three human cancer cell lines, CH1 (ovarian carcinoma), A549 (non-small cell lung cancer) and SW480 (colon carcinoma), as well as in vivo in a Hep3B SCID mouse xeno-transplantation model. 2H-Indazole tautomer stabilization in 1 has been confirmed by X-ray diffraction.
Affiliation: University of Vienna, Institute of Inorganic Chemistry, Währinger Strasse 42, A-1090 Vienna, Austria.Show MeSH
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Mentions: The aqueous solubility of 1 is 1.2 mM at 298 K, compared to 1.3 mM for 2. The aqueous solution behavior of 1 and 2 with respect to hydrolysis was studied by optical spectroscopy at 294 K over 24 h (Fig. 3). Both complexes are stable in aqueous solution. Immediate hydrolysis was excluded since the peak at m/z 485 assigned to [OsIVCl5(Hind)]− was observed in the negative ion ESI mass spectrum of the aqueous solution of both 1 and 2 after 24 h. The UV–vis spectra of 1 and 2 are compared in Fig. 4.
Affiliation: University of Vienna, Institute of Inorganic Chemistry, Währinger Strasse 42, A-1090 Vienna, Austria.