Synthesis, structure and catalase mimics of novel homoleptic manganese(II) complexes of 1,3-bis(2′-pyridylimino)isoindoline, Mn(4R-ind)2 (R=H, Me)

Kaizer, József; Baráth, Gábor; Speier, Gábor; Réglier, Marius; Giorgi, Michel

doi:10.1016/j.inoche.2006.11.002

Cited by 37 publications

(5 citation statements)

References 22 publications

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“…Many synthetic biomimetics of catalase and peroxidase are being developed as potential therapeutic agents against cancer, Alzheimer's aging and inflammatory and heart diseases [15][16][17][18], and as efficient catalytic systems for the degradation of various pollutants and bleaching which can be applied for example in food, dairy and textile industries [19][20][21][22][23][24]. Recently, we synthesized and characterized a series of mononuclear transition metal complexes with [M II (L n ) 2 ] (M = Fe(II) [25], Mn(II) [26,27], Ni(II) [27], Co(II) [28] and Cu(II) [29], n = 1, 2 and 4-6), [Fe III (L n )Cl 2 ] [30], [Cu II (HL n )X 2 ] (X = ClO 4 , Cl, n = 1, 2 and 4-6)] [29] and [Mn II (HL 1 and 5 )Cl 2 ] [31,32] compositions, and used as biomimetics of superoxide dismutase (SOD) [27], catalase [26,31,32], phenoxazinone synthase, catechol oxidase [33] and dioxygenase [30] enzymes. As a continuity of our research, we synthesized the analogs of [Mn II (HL 2-4, and 6 )Cl 2 ] complexes as catalysts against H 2 O 2 , and morin by the use of H 2 O 2 as an oxidant in context with the ligand modification by varying the aryl substituent on the bis-iminoisoindoline moiety and redox chemistry.…”

Section: Introductionmentioning

confidence: 99%

Design and Fine-Tuning Redox Potentials of Manganese(II) Complexes with Isoindoline-Based Ligands: H2O2 Oxidation and Oxidative Bleaching Performance in Aqueous Solution

Meena

Kaizer

2020

Catalysts

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A series of divalent manganese complexes [M II (HL 1-6 )Cl 2 ] with the 1,3-bis(2'-Ar-imino) isoindolines (HL n , n = 1-6, Ar = pyridyl, 4-methylpyridyl, imidazolyl, thiazolyl, benzimidazolyl and N-methylbenzimidazolyl, respectively) including the previously reported ligands (HL 1-2, 4-6 ) and complexes ([M II (HL 1,5 )Cl 2 ]) have been prepared and characterized by electrochemical and spectroscopic methods. In these complexes, it was possible to control the redox potential of the metal center by varying the aryl substituent on the bis-iminoisoindoline moiety, and investigate its effect in a catalase-like reaction, and oxidative bleaching process in buffered aqueous solution. The kinetics of the dismutation of H 2 O 2 into H 2 O and O 2 , and the oxidative degradation of morin by H 2 O 2 were investigated in buffered water, where the reactivity of the catalysts in both systems was markedly influenced by the redox and Lewis acidic properties of the metal centers and the concentration of the bicarbonate ions. Both the catalase-like and bleaching activity of the catalysts showed a linear correlation with the Mn III /Mn II redox potentials. The E 1/2 spans a 561 mV range from 388 mV (Ar = benzymidazolyl) to 948 mV (Ar = 4-methylpyridyl) vs. the SCE. The amount of bicarbonate is a critical issue for the in situ formation of peroxycarbonate as a versatile oxidant, and its participation in the formation of high valent Mn IV = O species.

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Section: Introductionmentioning

confidence: 99%

Design and Fine-Tuning Redox Potentials of Manganese(II) Complexes with Isoindoline-Based Ligands: H2O2 Oxidation and Oxidative Bleaching Performance in Aqueous Solution

Meena

Kaizer

2020

Catalysts

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“…The k cat value equaled 33 s −1 , however, was 3–4 times magnitudes lower when compared to the natural enzymes Thermus thermophilus (k cat = 2.6 × 10 5 s −1 ), Tricholoma album (k cat = 2.0 × 10 5 s −1 ), Lactobacillus plantarum (k cat = 2.6 × 10 4 s −1 ) and the heme-containing catalases (k cat = 4 × 10 7 s −1 ). Despite this iron complex presents lower values of catalytic efficiency than other models (Table 1) [49,50,51,52], it must be emphasized that this value was obtained in water and in pH close to the natural, representing an advantage of the title complex with respect to most of the published models, whose studies have been conducted in organic solvent due to the lack of solubility or activity in aqueous solution.…”

Section: Resultsmentioning

confidence: 80%

Stability and Catalase-Like Activity of a Mononuclear Non-Heme Oxoiron(IV) Complex in Aqueous Solution

et al. 2019

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Heme-type catalase is a class of oxidoreductase enzymes responsible for the biological defense against oxidative damage of cellular components caused by hydrogen peroxide, where metal-oxo species are proposed as reactive intermediates. To get more insight into the mechanism of this curious reaction a non-heme structural and functional model was carried out by the use of a mononuclear complex [FeII(N4Py*)(CH3CN)](CF3SO3)2 (N4Py* = N,N-bis(2-pyridylmethyl)- 1,2-di(2-pyridyl)ethylamine) as a catalyst, where the possible reactive intermediates, high-valent FeIV=O and FeIII–OOH are known and spectroscopically well characterized. The kinetics of the dismutation of H2O2 into O2 and H2O was investigated in buffered water, where the reactivity of the catalyst was markedly influenced by the pH, and it revealed Michaelis–Menten behavior with KM = 1.39 M, kcat = 33 s−1 and k2(kcat/KM) = 23.9 M−1s−1 at pH 9.5. A mononuclear [(N4Py)FeIV=O]2+ as a possible intermediate was also prepared, and the pH dependence of its stability and reactivity in aqueous solution against H2O2 was also investigated. Based on detailed kinetic, and mechanistic studies (pH dependence, solvent isotope effect (SIE) of 6.2 and the saturation kinetics for the initial rates versus the H2O2 concentration with KM = 18 mM) lead to the conclusion that the rate-determining step in these reactions above involves hydrogen-atom transfer between the iron-bound substrate and the Fe(IV)-oxo species.

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“…A number of mechanistic and spectroscopic studies have been reported on the catalase activity of non-porphyrin mono- and dinuclear complexes with various ligands including Schiff bases, corroles, polyamines and polypyridyl derivatives. These papers mainly focused on the comparison of mono and dinuclear copper, manganese and iron complexes and the effect of various factors such as ligand donor sites, endogenous acid/base groups and steric parameters [ 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 ].…”

Section: Introductionmentioning

confidence: 99%

Effect of Redox Potential on Diiron-Mediated Disproportionation of Hydrogen Peroxide

2023

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Heme and nonheme dimanganese catalases are widely distributed in living organisms to participate in antioxidant defenses that protect biological systems from oxidative stress. The key step in these processes is the disproportionation of H2O2 to O2 and water, which can be interpreted via two different mechanisms, namely via the formation of high-valent oxoiron(IV) and peroxodimanganese(III) or diiron(III) intermediates. In order to better understand the mechanism of this important process, we have chosen such synthetic model compounds that can be used to map the nature of the catalytically active species and the factors influencing their activities. Our previously reported μ-1,2-peroxo-diiron(III)-containing biomimics are good candidates, as both proposed reactive intermediates (FeIVO and FeIII2(μ-O2)) can be derived from them. Based on this, we have investigated and compared five heterobidentate-ligand-containing model systems including the previously reported and fully characterized [FeII(L1−4)3]2+ (L1 = 2-(2′-pyridyl)-1H-benzimidazole, L2 = 2-(2′-pyridyl)-N-methyl-benzimidazole, L3 = 2-(4-thiazolyl)-1H-benzimidazole and L4 = 2-(4′-methyl-2′-pyridyl)-1H-benzimidazole) and the novel [FeII(L5)3]2+ (L5 = 2-(1H-1,2,4-triazol-3-yl)-pyridine) precursor complexes with their spectroscopically characterized μ-1,2-peroxo-diiron(III) intermediates. Based on the reaction kinetic measurements and previous computational studies, it can be said that the disproportionation reaction of H2O2 can be interpreted through the formation of an electrophilic oxoiron(IV) intermediate that can be derived from the homolysis of the O–O bond of the forming μ-1,2-peroxo-diiron(III) complexes. We also found that the disproportionation rate of the H2O2 shows a linear correlation with the FeIII/FeII redox potential (in the range of 804 mV-1039 mV vs. SCE) of the catalysts controlled by the modification of the ligand environment. Furthermore, it is important to note that the two most active catalysts with L3 and L5 ligands have a high-spin electronic configuration.

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Synthesis, structure and catalase mimics of novel homoleptic manganese(II) complexes of 1,3-bis(2′-pyridylimino)isoindoline, Mn(4R-ind)2 (R=H, Me)

Cited by 37 publications

References 22 publications

Design and Fine-Tuning Redox Potentials of Manganese(II) Complexes with Isoindoline-Based Ligands: H2O2 Oxidation and Oxidative Bleaching Performance in Aqueous Solution

Design and Fine-Tuning Redox Potentials of Manganese(II) Complexes with Isoindoline-Based Ligands: H2O2 Oxidation and Oxidative Bleaching Performance in Aqueous Solution

Stability and Catalase-Like Activity of a Mononuclear Non-Heme Oxoiron(IV) Complex in Aqueous Solution

Effect of Redox Potential on Diiron-Mediated Disproportionation of Hydrogen Peroxide

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