DFT studies of the effectiveness of p-phenylenediamine antioxidants through their Cu(II) coordination ability

2016

Acta Chimica Slovaca

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NMR shifts of N-phenyl-N'-alkyl-p-phenylenediamines (PPD) in vacuum were evaluated by B3LYP calculations using GIAO method. According to our previous studies, the Molar Antioxidant Effectiveness (AEM) of PPD antioxidants correlates with NMR chemical shifts of the amine nitrogen between aromatic rings (N A ), the side aliphatic chain nitrogen (N B ) and its neighboring tertiary carbon atom (C T ) as well as of the hydrogens bonded to them. Our results indicate that the above mentioned chemical shifts correlate with increasing reactivity of dehydrogenated PPD antioxidants at these sites as well.

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Antioxidant effectiveness of dehydrogenated p-phenylene diamines through NMR calculations

Puškárová

2016

Acta Chimica Slovaca

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“…Another modification of the above mentioned method has been used for both N centers of a series of para-phenylene diamine (PPD) antioxidants. [16] Nearly linear dependence of the experimental antioxidant effectiveness on Cu(II)-PPD interaction energies, Cu atomic charges and other electron density parameters has been deduced.…”

Section: Introductionmentioning

confidence: 91%

Quantum-chemical studies of rutile nanoparticles toxicity I. Defect-free rod-like model clusters

2019

Acta Chimica Slovaca

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Using semiempirical PM6 method, the structures of a rod-like [Ti40O124H81] -7 model cluster and of the [Ti40O124H81Cu] -5 ones with Cu 2+ coordinated at various sites were optimized. If the relative toxicity of individual Ti centers in rod-like rutile nanoparticles can be evaluated by the electron density transfer to a Cu 2+ probe, its maximal values may be ascribed to the pentacoordinated corner and hexacoordinated edge ones with three Ti-OH bonds. However, these centers exhibit the least negative interaction energies which can be compensated by the significantly better accessibility of the corner Ti center in comparison with the remaining ones. The Ti centers with the most negative interaction energy parameters exhibit the lowest extent of the electron density transfer to a Cu 2+ probe. The rutile nanoparticles destruction starts at pentacoordinated Ti face centers

“…In agreement with experimental investigations, the higher antioxidant activity of individual compounds and their reaction sites may be assigned to higher MIA values and higher reducing character toward Cu(II). Another modification of the above-mentioned method has been used for both N centers of a series of para-phenylene diamine (PPD) antioxidants [9]. Nearly linear dependence of the experimental antioxidant effectiveness on Cu(II)-PPD interaction energies, Cu atomic charges and other electron density parameters has been deduced.…”

Section: Introductionmentioning

confidence: 99%

On shape dependence of the toxicity of rutile nanoparticles

2020

J Nanopart Res

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Using B3LYP method, the nearly spheric structure of [Ti7O28H26] 2-, the rod-like structures of [Ti2O10H10] 2and [Ti7O30H10] 2chains and the structures of their neutral complexes with Cu 2+ coordinated at various terminal or bridging oxygen sites were optimized in order to assess the toxicity of rutile nanoparticles. Culigand interaction energy parameters and Cu charges were evaluated. Spheric structures are more reactive than the rod-like chains of the (nearly) same size.The reverse relation holds for the degree of their toxicity as indicated by the extent of the electron density transfer to a Cu 2+ probe. The experimentally observed higher cytotoxicity of rod-like nanoparticles in comparison with the spheric ones might be explained by the higher electron density transfer to the interacting cells.