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Investigation of Cobalt(III)‐Tetrachlorocatechol Complexes as Models for Catechol‐Based Anticancer Prodrugs
Author(s) -
da Silva Aline Farias Moreira,
de Mello Marcos Vinícius Palmeira,
Gómez Javier G.,
Ferreira Glaucio Braga,
Lanznaster Mauricio
Publication year - 2019
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201801550
Subject(s) - chemistry , cobalt , redox , cyclic voltammetry , ascorbic acid , sodium dithionite , inorganic chemistry , dissociation (chemistry) , mass spectrometry , medicinal chemistry , electrochemistry , nuclear chemistry , food science , electrode , chromatography
Two novel cobalt(III) complexes, [Co(TPA)(TCC)]ClO 4 · H 2 O ( 1 ) and [Co(py 2 en)(TCC)]ClO 4 · 2H 2 O ( 2 ), were synthesized and fully characterized by IR, UV/Vis and 1 H NMR spectroscopy, ESI mass spectrometry, and X‐ray diffraction. Cyclic voltammetry experiments revealed an irreversible reduction of the Co 3+ center for both complexes. The Co 3+ /Co 2+ redox potential, –0.91 V for 1 and –1.15 V for 2 (vs. Fc/Fc + ), was obtained by square wave voltammetry in DMSO. Reactions of 1 and 2 with ascorbic acid and sodium dithionite at pH 7.4 and 6.2 were carried out in argon and open‐air atmospheres, to simulate biological redox activation under hypoxia and normoxia. Neither the Co 3+ /Co 2+ reduction nor the dissociation of TCC 2– was observed. Thermodynamic parameters calculated for the Co 3+ /Co 2+ reduction and substitution of the TCC 2– ligand by water indicate an endothermic non‐spontaneous reaction.