Reversible Oxygenation of 2,4-Diaminobutanoic Acid-Co(II) Complexes

Cheng, Xiang; Huang, Yan; Li, Hui; Yue, Fan; Wen, Hongmei; Wang, Jide

doi:10.1155/2016/8296365

Cited by 2 publications

(1 citation statement)

References 27 publications

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“…In biological applications the metal complexes of organometallic Schiff bases have been studied mainly for their fungicidal and insecticidal activity 11 . The synthetic reversible oxygen carrying complexes are of interest as model compounds in the study of the reversible oxygenation mechanism involved in complex natural oxygen carriers such as haemoglobin [12][13][14][15][16] . In this paper the synthesis of new organometallic Schiff base compound and their complexes were characterized on the basis of elemental analysis, magnetic susceptibility, Conductivity IR, UV-Visible, Mass spectra and TGA/DTA.…”

Section: Introductionmentioning

confidence: 99%

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2017

IJPSR

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O] were used to compare their stoichiometric composition and it found that near about equal to the theoretical mass of the complex and prepared ligand. Synthesis of nanoparticles of OMNPs (organometallic Nanoparticles) of Cu(II) Complex with SEM and EDX were recorded and particle size is in between 52-60nm. The ligand and complexes have been screened for its anti-fungal activities against three fungi Alternaria brassicae, Aspergillus niger, Fusarium oxysporum.

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Section: Introductionmentioning

confidence: 99%

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2017

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Reversible uptake of molecular oxygen by heteroligand Co(II)–l-α-amino acid–imidazole systems: equilibrium models at full mass balance

Pająk

Woźniczka

Vogt

et al. 2017

Chemistry Central Journal

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BackgroundThe paper examines Co(II)–amino acid–imidazole systems (where amino acid = l-α-amino acid: alanine, asparagine, histidine) which, when in aqueous solutions, activate and reversibly take up dioxygen, while maintaining the structural scheme of the heme group (imidazole as axial ligand and O2 uptake at the sixth, trans position) thus imitating natural respiratory pigments such as myoglobin and hemoglobin. The oxygenated reaction shows higher reversibility than for Co(II)–amac systems with analogous amino acids without imidazole. Unlike previous investigations of the heteroligand Co(II)–amino acid–imidazole systems, the present study accurately calculates all equilibrium forms present in solution and determines the equilibrium constants without using any simplified approximations. The equilibrium concentrations of Co(II), amino acid, imidazole and the formed complex species were calculated using constant data obtained for analogous systems under oxygen-free conditions. Pehametric and volumetric (oxygenation) studies allowed the stoichiometry of O2 uptake reaction and coordination mode of the central ion in the forming oxygen adduct to be determined. The values of dioxygen uptake equilibrium constants were evaluated by applying the full mass balance equations.ResultsInvestigations of oxygenation of the Co(II)–amino acid–imidazole systems indicated that dioxygen uptake proceeds along with a rise in pH to 9–10. The percentage of reversibility noted after acidification of the solution to the initial pH ranged within ca 30–60% for alanine, 40–70% for asparagine and 50–90% for histidine, with a rising tendency along with the increasing share of amino acid in the Co(II): amino acid: imidazole ratio. Calculations of the share of the free Co(II) ion as well as of the particular complex species existing in solution beside the oxygen adduct (regarding dioxygen bound both reversibly and irreversibly) indicated quite significant values for the systems with alanine and asparagine—in those cases the of oxygenation reaction is right shifted to a relatively lower extent. The experimental results indicate that the “active” complex, able to take up dioxygen, is a heteroligand CoL2L′complex, where L = amac (an amino acid with a non-protonated amine group) while L′ = Himid, with the N1 nitrogen protonated within the entire pH range under study. Moreover, the corresponding log value at various initial total Co(II), amino acid and imidazole concentrations was found to be constant within the limits of error, which confirms those results. The highest log value, 14.9, occurs for the histidine system; in comparison, asparagine is 7.8 and alanine is 9.7. This high value is most likely due to the participation of the additional effective N3 donor of the imidazole side group of histidine.ConclusionsThe Co(II)–amac–Himid systems formed by using a [Co(imid)2]n polymer as starting material demonstrate that the reversible uptake of molecular oxygen occurs by forming dimeric μ-peroxy adducts. The essential impact on the electron structur...

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Reversible Oxygenation of 2,4-Diaminobutanoic Acid-Co(II) Complexes

Cited by 2 publications

References 27 publications

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Reversible uptake of molecular oxygen by heteroligand Co(II)–l-α-amino acid–imidazole systems: equilibrium models at full mass balance

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