Electrochemical and ESR study of 5-nitrofuryl-containing thiosemicarbazones antiprotozoal drugs.
Cyclic voltammetry and electron spin resonance (ESR) techniques were used in the investigation of several potential antiprotozoal thiosemicarbazones nitrofurane derivatives. A self-protonation process involving the protonation of the nitro group due to the presence of an acidic proton in the thiosemicarbazone moiety was observed in the first step of a CEE(rev) reduction mechanism of these derivatives. ESR spectra of the free radicals obtained by electrolytic reduction were characterized and analyzed. AM1 methodology was used to obtain the optimized geometries and UB3LYP calculations were performed to obtain the theoretical hyperfine coupling constants. The theoretical study exhibited an unusual assignment of the spin densities showing a free radical centered in the thiosemicarbazone moiety rather than the nitro which are in agreement with the experimental hyperfine pattern.
Rigol
Carolina
C
Departamento de Química Inorgánica y Analítica, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Olivos 1007 Independencia, Santiago, Chile.
Olea-Azar
C
C
Mendizábal
Fernando
F
Otero
Lucía
L
Gambino
Dinorah
D
González
Mercedes
M
Cerecetto
Hugo
H
D000981:Antiprotozoal Agents / Q000737:chemistry*; D004563:Electrochemistry; D004578:Electron Spin Resonance Spectroscopy; D015394:Molecular Structure; D009581:Nitrofurans / Q000737:chemistry*; D009584:Nitrogen / Q000737:chemistry; D010084:Oxidation-Reduction; D013882:Thiosemicarbazones / Q000737:chemistry*
D000981:Antiprotozoal Agents; D009581:Nitrofurans; D013882:Thiosemicarbazones; D009584:Nitrogen