Catalase and epoxidation activity of polynuclear manganese(III)–Schiff base complexes
TL;DR: In this paper, the catalase activity of these complexes were studied in aqueous, dimethylformamide and methanol medium, and they catalyzed the epoxidation of cyclohexene with H 2 O 2 in the presence of imidazole.
Abstract: Polynucleating Schiff base ligands, poly(2,5-dihydroxyterephthalaldehyde ethylenediamine diprotonated) (PdhterenH 2 ) and poly(2,5-dihydroxyterephthalaldehyde propyldiamine diprotonated) (PdhterpnH 2 ) were synthesized by condensation reactions of 2,5-dihydroxyterephthalaldehyde (dhterH 2 ) with ethylenediamine and propylenediamine, respectively. Insoluble polynuclear manganese(III)–Schiff base complexes, [Mn n (Pdhteren)(OAc) n ] 1 and [Mn n (Pdhterpn)(OAc) n ] 2 were prepared by refluxing manganese(III)-acetate and the respective polymeric Schiff bases in ethanol. The catalase activity of these complexes were studied in aqueous, dimethylformamide and methanol medium. These complexes catalyze the epoxidation of cyclohexene with H 2 O 2 in the presence of imidazole.
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TL;DR: In this paper, a review describes examples of remarkable acceleration of metal-catalyzed oxidation reactions by certain additives, which can not only dramatically improve yields of oxygenates but also control the selectivity of the reaction.
Abstract: This review describes examples of remarkable acceleration of metal-catalyzed oxidation reactions by certain additives. In some cases, reactions proceed 2 or 10 times more rapidly in comparison with the process in the additive’s absence, in other cases, reactions become possible only in the presence of the additive. Varying ligands at the metal center or additives, one can not only dramatically improve yields of oxygenates but also control the selectivity of the reaction. Understanding mechanisms of the additive’s action is very important for search of new efficient catalysts and catalytic systems. Additives considered in the review can play roles of the ligands at metal ion or proton or electron transfer reagents and they mimic certain enzymes (the active center or its environment). Often the mechanism of the effect of additives on the reaction rate and the product yield is unknown, and the main aim of the review is to attract investigator’s attention in creating new efficient catalytic systems, which contain not only a metal ion but also a necessary “additive”.
443 citations
TL;DR: The manganese(IV) complex salt [L2Mn2O3](PF6)2 (L = 1,4,7-trimethyl-1, 4, 7-triazacyclonononane) (compound 1, see Scheme 1) very efficiently catalyzes the hydroperoxidation of saturated hydrocarbons, including ethane by H2O2 in acetontitrile or nitromethane solution at low (room or lower) temperature, provided a carboxylic (typically acetic) acid is present
Abstract: The manganese(IV) complex salt [L2Mn2O3](PF6)2 (L = 1,4,7-trimethyl-1,4,7-triazacyclononane) (compound 1, see Scheme 1) very efficiently catalyzes the hydroperoxidation of saturated hydrocarbons, including ethane by H2O2 in acetontitrile or nitromethane solution at low (room or lower) temperature, provided a carboxylic (typically acetic) acid is present. The hydroperoxidation of tertiary positions in disubstituted cyclohexanes proceeds with partial retention of configuration in nitromethane or acetonitrile solution, while the stereoselectivity of the reaction is only negligible in acetone solution. The system “H2O2–compound 1–MeCO2H” also transforms secondary alcohols into the corresponding ketones with quantitative yields at room temperature within a few minutes; the yields of aldehydes and carboxylic acids in the oxidation of primary alcohols are lower. Terminal aliphatic olefins such as hexene-1 are quantitatively epoxidized by the same system in acetonitrile at room temperature within 20 min, while the epoxide yield in the analogous reaction with styrene attains only 60% under the same conditions. Finally, dimethylsulfide can be quantitatively and selectively converted into dimethylsulfoxide within 3 h at room temperature. The system “tert-BuOOH–compound 1” also oxidizes alkanes, addition of acetic acids has less pronounced effect on the direction and efficiency of the reaction. Two other checked derivative of Mn(IV) (compounds 2 and 3) as well a porphyrin complex of Mn(III) (compound 4) exhibited lower activity in catalysis of alkane oxidation with tert-BuOOH. © 2001 Elsevier Science B.V. All rights reserved.
153 citations
30 Dec 2004
TL;DR: In this paper, the synthesis methods of polyimines by polycondensation, using diamines or hydrazine and dialdehydes, or by chemical and electrochemical polymerization of imine oligomers containing terminal oxidable groups (pyrrole, thiophene, furan, naphthalene, etc).
Abstract: In the last few years, polymers with highly conjugated chains have attracted much attention because of their wide variety of applications in the field of electronics, opto‐electronics, and photonics. Polyimines (PIs) (polymeric Schiff bases) is a class of polymer family, which has been less reviewed. In this paper, we focus on the synthesis methods of PIs by polycondensation, using diamines or hydrazine and dialdehydes, diketones or quinone compounds, or by chemical and electrochemical polymerization of imine oligomers containing terminal oxidable groups (pyrrole, thiophene, furan, naphthalene, etc). PIs with liquid crystalline behavior or having rotaxane and dendrimer architectures are also discussed. Structure, thermal, opto‐electronic, electrical, and mechanical properties and some potential applications of this class of polymers are presented in the last chapters.
151 citations
TL;DR: In this paper, a stable two electron transfer solid-liquid reaction based on MnO2 and soluble Mn(CH3COO)2(Mn(Ac)2) under neutral medium was presented.
Abstract: Manganese (Mn) based batteries have attracted remarkable attention due to their attractive features of low cost, earth abundance and environmental friendliness. However, the poor stability of the positive electrode due to the phase transformation and structural collapse issues has hindered their validity for rechargeable batteries. Here we presented a highly reversible and stable two electron transfer solid–liquid reaction based on MnO2 and soluble Mn(CH3COO)2(Mn(Ac)2) under neutral medium. Benefiting from the coordination effect of Ac−, the Mn2+ can directly deposit on the electrode in the form of MnO2, which is completely different from other manganese salts (MnSO4 or MnCl2). Compared with the common intercalation mechanism cathode, the dissolution/deposition reaction completely avoided the structure collapse issue, which results in a dramatic improvement in stability. Furthermore, in contrast to the redox pair of Mn3+/Mn2+, the intrinsic problems caused by the disproportionation of Mn3+ can be totally avoided. The proof of concept can be confirmed by a neutral Zn–Mn flow battery with an optimized electrolyte. The MnO2 could be perfectly deposited on the graphite fiber with an areal capacity of 20 mA h cm−2, which is the highest value ever reported. Unlike the alkaline electrolytes, a neutral flow system can effectively avoid the zinc dendrite issues. As a result, a Zn–Mn flow battery demonstrated a CE of 99% and an EE of 78% at 40 mA cm−2 with more than 400 cycles. Combined with excellent electrochemical reversibility, low cost and two-electron transfer properties, the Zn–Mn battery can be a very promising candidate for large scale energy storage.
148 citations
TL;DR: A series of Schiff-base complexes has been synthesized by the condensation of 1,2-diaminocyclohexane with salicylaldehyde, 2-pyridine carboxaldehyde, and 2-hydroxy-1-naphthaldehyde, followed by the metallation with manganese ( 1, 2, 3a ), cobalt ( 3b ), copper ( 3c ), and iron ( 3d ) salts.
Abstract: A series of Schiff-base complexes has been synthesized by the condensation of 1,2-diaminocyclohexane with salicylaldehyde, 2-pyridinecarboxaldehyde, and 2-hydroxy-1-naphthaldehyde, followed by the metallation with manganese ( 1 , 2 , 3a ), cobalt ( 3b ), copper ( 3c ) and iron ( 3d ) salts. These Schiff-base ligands L 1 – L 3 and complexes 1 , 2 , 3a – d were then characterized by IR, 1 H NMR, 13 C NMR, UV–vis spectra, and DSC measurement. Schiff-base Mn complex ( 3a ) resulting from N , N ′-bis(2-hydroxy-1-naphthalidene)cyclohexanediamine ( L 3 ) ligand was considerably active for the catalytic epoxidation of styrene under mild conditions, in which the highest yield of styrene oxide reached 91.2 mol%, notably higher than those achieved from simple salt catalysts Mn(Ac) 2 ·4H 2 O and MnSO 4 ·H 2 O. However, another two salen–Mn complexes 1 and 2 derived from ligands N , N ′-bis(salicylidene)cyclohexanediamine ( L 1 ) and N , N ′-bis(2-pyridine carboxalidene)cyclohexanediamine ( L 2 ) exhibited relatively poor activity under identical experimental conditions.
101 citations
References
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Book•
01 Jan 1978TL;DR: In this article, the normal modes of vibration are illustrated and corresponding vibrational frequencies are listed for each type, including diatomic, triatomic, fouratomic, five-atomic, six-atomic and seven-atomic types.
Abstract: Inorganic molecules (ions) and ligands are classified into diatomic, triatomic, four-atomic, five-atomic, six-atomic, and seven-atomic types, and their normal modes of vibration are illustrated and the corresponding vibrational frequencies are listed for each type. Molecules of other types are grouped into compounds of boron, carbon, silicon, nitrogen, phosphorus, and sulfur, and the structures and infrared (IR)/Raman spectra of select examples are shown for each group. Group frequency charts including band assignments are shown for phosphorus and sulfur compounds. Other group frequency charts include hydrogen stretching frequencies, halogen stretching frequencies, oxygen stretching and bending frequencies, inorganic ions, and metal complexes containing simple coordinating ligands.
Keywords:
inorganic compounds;
coordination compounds;
diatomic molecules (ligands);
triatomic molecules (ligands);
four-atomic molecules (ligands);
five-atomic molecules (ligands);
six-atomic molecules (ligands);
seven-atomic molecules (ligands);
boron compounds;
carbon compounds;
silicon compounds;
nitrogen compounds;
phosphorus compounds;
sulfur compounds;
group frequency charts
15,951 citations
Book•
01 Jan 1966
TL;DR: Common physical techniques used in purification chemical methods used in Purification purification of organic chemicals Purification of inorganic and metal organic chemicals general methods for the purification classification of classes of compounds and natural products biochemicals and related products as mentioned in this paper.
Abstract: Common physical techniques used in purification chemical methods used in purification purification of organic chemicals purification of inorganic and metal organic chemicals general methods for the purification of classes of compounds purification of natural products biochemicals and related products.
10,132 citations
TL;DR: Structural factors that influence functional properties are examined in the case of four heme enzymes and the importance of synthetic porphyrin models in understanding the properties of the protein-free metal center is emphasized.
Abstract: Structural factors that influence functional properties are examined in the case of four heme enzymes: cytochrome P-450, chloroperoxidase, horseradish peroxidase, and secondary amine mono-oxygenase. The identity of the axial ligand, the nature of the heme environment, and the steric accessibility of the heme iron and heme edge combine to play major roles in determining the reactivity of each enzyme. The importance of synthetic porphyrin models in understanding the properties of the protein-free metal center is emphasized. The conclusions described herein have been derived from studies at the interface between biological and inorganic chemistry.
848 citations
TL;DR: Augmentation d'activite avec des substituants attracteurs d'electrons (dichloro ou dinitro)
Abstract: Augmentation d'activite avec des substituants attracteurs d'electrons (dichloro ou dinitro)
746 citations