TY - JOUR
T1 - Ascorbyl and hydroxyl radical generation mediated by a copper complex adsorbed on gold
AU - Romo, Adolfo I. B.
AU - Dibo, Vitória S.
AU - Abreu, Dieric S.
AU - Carepo, Marta S. P.
AU - Neira, Andrea C.
AU - Castillo, Ivan
AU - Lemus, Luis
AU - Nascimento, Otaciro R.
AU - Bernhardt, Paul V.
AU - Sousa, Eduardo H. S.
AU - Diógenes, Izaura C. N.
N1 - CAPES (PROEX 23038.000936/2018-46
PRINT 88887.311905/2018-00)
CNPq (E. H. S. Sousa 312030/2015-0,
I. C. N. Diogenes 307078/2017-5),
FUNCAP (PRONEX PR2 0101-00030.01.00/15 SPU No.: 3265612/2015)
UNAM (I. Castillo 348-2018; A. C. Neira 293842)
CONICYT (A. I. B. Romo #72170429)
Sem PDF conforme despacho.
PY - 2019/10/7
Y1 - 2019/10/7
N2 - This work presents the results obtained for a thioether derivative of bipyridine, (E,Z)-1-(4′-methyl-[2,2′-bipyridine]-4-yl)-N-(4(methylthio)phenyl)methanimine (4-mbpy-Bz-SMe), and its copper complex [CuII(4-mbpy-Bz-SMe)2]2+. Electronic spectra acquired at 183 K of the cuprous complex [CuI(4-mbpy-Bz-SMe)2]+ generated in situ indicated the formation of the peroxodicopper compound {[CuII(4-mbpy-Bz-SMe)2]2(μ-O22-)}2+. A gold electrode modified with [CuII(4-mbpy-Bz-SMe)2]2+ (Au/[Cu]) was fully characterized by SERS spectroscopy, electrochemistry and impedance spectroscopy thus showing adsorption occurs through the sulfur atom of the 4-mbpy-Bz-SMe moieties. DNA cleavage assays showed the copper complex, in solution and adsorbed on gold, degrades DNA if reducing conditions are maintained, i.e. ascorbic acid (H2AA) in solution or applied potentials more negative than 0.12 V vs. Ag/AgCl (CuI form). The electron paramagnetic resonance (EPR) spectra obtained for the electrolyzed solution (Eapl = -0.2 V, no H2O2) and for the solution containing [CuII(4-mbpy-Bz-SMe)2]2+ and H2O2 showed hydroxyl radical, HO, generation had occurred. The cyclic voltammograms obtained with H2AA in solution at Au/[CuII(4-mbpy-Bz-SMe)2]2+ as the working electrode showed a one-electron reaction leading to the ascorbyl radical (HA), which was detected by EPR. The current assigned to the electrode oxidation of HA to AA decreased with the addition of catalase, a scavenger of H2O2, meaning peroxide is involved in the mechanism.
AB - This work presents the results obtained for a thioether derivative of bipyridine, (E,Z)-1-(4′-methyl-[2,2′-bipyridine]-4-yl)-N-(4(methylthio)phenyl)methanimine (4-mbpy-Bz-SMe), and its copper complex [CuII(4-mbpy-Bz-SMe)2]2+. Electronic spectra acquired at 183 K of the cuprous complex [CuI(4-mbpy-Bz-SMe)2]+ generated in situ indicated the formation of the peroxodicopper compound {[CuII(4-mbpy-Bz-SMe)2]2(μ-O22-)}2+. A gold electrode modified with [CuII(4-mbpy-Bz-SMe)2]2+ (Au/[Cu]) was fully characterized by SERS spectroscopy, electrochemistry and impedance spectroscopy thus showing adsorption occurs through the sulfur atom of the 4-mbpy-Bz-SMe moieties. DNA cleavage assays showed the copper complex, in solution and adsorbed on gold, degrades DNA if reducing conditions are maintained, i.e. ascorbic acid (H2AA) in solution or applied potentials more negative than 0.12 V vs. Ag/AgCl (CuI form). The electron paramagnetic resonance (EPR) spectra obtained for the electrolyzed solution (Eapl = -0.2 V, no H2O2) and for the solution containing [CuII(4-mbpy-Bz-SMe)2]2+ and H2O2 showed hydroxyl radical, HO, generation had occurred. The cyclic voltammograms obtained with H2AA in solution at Au/[CuII(4-mbpy-Bz-SMe)2]2+ as the working electrode showed a one-electron reaction leading to the ascorbyl radical (HA), which was detected by EPR. The current assigned to the electrode oxidation of HA to AA decreased with the addition of catalase, a scavenger of H2O2, meaning peroxide is involved in the mechanism.
UR - http://www.scopus.com/inward/record.url?scp=85072587165&partnerID=8YFLogxK
U2 - 10.1039/c9dt01726g
DO - 10.1039/c9dt01726g
M3 - Article
C2 - 31498349
AN - SCOPUS:85072587165
SN - 1477-9226
VL - 48
SP - 14128
EP - 14137
JO - Dalton Transactions
JF - Dalton Transactions
IS - 37
ER -