A New Diazacyclooctane Dihydroxamate as a Siderophore Analogue − Synthesis and Equilibrium Studies of Iron(<scp>III</scp>) and Copper(<scp>II</scp>) Complexes

Gaspar, Margarida; Telo, João P.; Santos, M. Amélia

doi:10.1002/ejic.200300159

Cited by 6 publications

(2 citation statements)

References 40 publications

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“…As r t increases, the Cu d − d transition is red-shifted in most samples, indicating the formation of a polynuclear complex, CuNO 5 , at the expense of mononuclear ones, CuN 2 O 4 and CuN 4 O 2 . These structure assignments are supported by λ max values of similar complexes synthesized in solution from known ratios of [Cu(H 2 O) 6 ] 2+ and ammonia, ethylenediamine, , APTS, or AAPTS (Figure and Table ). The slight differences observed between the λ max of the solid and the solutions can be explained by the fact that basic silanols groups are able to replace H 2 O in [Cu(H 2 O) 6 ] 2+ .…”

Section: Resultsmentioning

confidence: 59%

Toward Efficient Nanoporous Catalysts: Controlling Site-Isolation and Concentration of Grafted Catalytic Sites on Nanoporous Materials with Solvents and Colorimetric Elucidation of Their Site-Isolation

et al. 2007

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We report that the polarity and dielectric constants of solvents used for grafting organosilanes on mesoporous materials strongly affect the concentration of grafted organic groups, the degree of their site-isolation, and the catalytic properties of the resulting materials. Polar and nonpolar organosilanes as well as polar-protic, dipolar-aprotic, and nonpolar solvents were investigated. Polar-protic solvents, which have high dielectric constants, resulted in smaller concentrations ( approximately 1-2 mmol/g) of polar organic groups such as 3-aminopropyl groups, higher surface area materials, site-isolated organic groups, and more efficient catalytic properties toward the Henry reaction of p-hydroxybenzaldehyde with nitromethane. On the other hand, dipolar-aprotic and nonpolar solvents resulted in larger concentrations ( approximately 2-3 mmol/g) of grafted polar functional groups, lower-to-higher surface area materials, more densely populated catalytic groups, and poor-to-efficient catalytic properties toward the Henry reaction. Both the polar-protic and dipolar-aprotic solvents resulted in significantly lower concentration of grafted groups for nonpolar organosilanes such as (3-mercaptopropyl)trimethoxysilane compared to corresponding grafting of the polar amino-organosilanes. The relationship between the solvent properties and the percentage and degree of site-isolation of the grafted functional groups was attributed to differences in solvation of the organosilanes and silanols in various solvents and possible hydrogen-bonding between the organsilanes and the solvents. The degree of site-isolation of the amine groups, which affect the material's catalytic properties, was elucidated by a new colorimetric method involving probing of the absorption maxima (lambdamax) on the d-d electronic spectrum of Cu2+ complexes with the amine-functionalized materials and the colors of the samples. The absorption lambdamax and the colors of the materials were found to be uniquely dependent on the type of solvents used for grafting the organoamines. For instance, the monoamine- and diamine-functionalized samples grafted in methanol resulted in pale blue and light purple colors with lambdamax at approximately 720 and 650 nm, respectively. These correspond to CuNO5 and CuN2O4 structures, respectively, which are indicative of the presence of site-isolated organoamines in samples grafted in methanol. The monoamine and diamine samples grafted in toluene resulted in purple and deep purple colors with lambdamax at approximately 590 and 630 nm, respectively. These correspond to CuN2O4 and CuN4O2, which are indicative of the presence of closely spaced organoamines in samples grafted in toluene. The samples grafted in isopropanol gave colors and lambdamax intermediate between those of samples grafted in toluene and methanol.

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Section: Resultsmentioning

confidence: 59%

Toward Efficient Nanoporous Catalysts: Controlling Site-Isolation and Concentration of Grafted Catalytic Sites on Nanoporous Materials with Solvents and Colorimetric Elucidation of Their Site-Isolation

et al. 2007

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“…The formation of a dimeric species is well known in iron-TPA chemistry, 32 and formation of iron complex(es) with more than one hydroxamato or hydroximato moiety coordinated to the metal centre would account for the signal at g = 4.27 in EPR. 33 Indeed, the formation of the trishydroxamate species Fe(RC(O)-NHO) 3 has been reported during the synthesis of the complexes Fe(salen)(RC(O)-NHO) (R=CH 3 , Ph) in methanol. 34 This journal is © The Royal Society of Chemistry 2008…”

Section: Discussionmentioning

confidence: 99%

Synthesis and characterization of mononuclear hydroxamato and hydroximato complexes of iron(iii) based on the tris-(2-pyridylmethyl)amine ligand

et al. 2008

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The reaction of acetohydroxamic (CH3C(O)-NHOH), benzhydroxamic acid (PhC(O)-NHOH) or 1-hydroxypyridin-2(1H)-one (pyrC(O)-NOH) in the presence of tris-(2-pyridylmethyl)amine (TPA), sodium methoxide and an iron(III) salt yields the mononuclear complexes [Fe(TPA)(CH3C(O)-NHO)]2+ (), [Fe(TPA)(PhC(O)-NHO)]2+ () and [Fe(TPA)(pyrC(O)-NO)]2+ (). The hydroxamato complexes and are easily converted to their hydroximato form [Fe(TPA)(CH3C(O)=NO)]+ () and [Fe(TPA)(PhC(O)=NO)]+ () by addition of base. The complexes described were characterized by UV-vis spectroscopy, EPR and cyclic voltammetry, as well as single-crystal X-ray crystallography for and .

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Magnetic properties of iron(III) complex with 1,5-bis(N-methylaceto-hydroxamic acid) derivative

Pardasani

2022

Magnetic Properties of Paramagnetic Compounds, Magnetic Susceptibility Data, Volume 5

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A New Diazacyclooctane Dihydroxamate as a Siderophore Analogue − Synthesis and Equilibrium Studies of Iron(III) and Copper(II) Complexes

Cited by 6 publications

References 40 publications

Toward Efficient Nanoporous Catalysts: Controlling Site-Isolation and Concentration of Grafted Catalytic Sites on Nanoporous Materials with Solvents and Colorimetric Elucidation of Their Site-Isolation

Toward Efficient Nanoporous Catalysts: Controlling Site-Isolation and Concentration of Grafted Catalytic Sites on Nanoporous Materials with Solvents and Colorimetric Elucidation of Their Site-Isolation

Synthesis and characterization of mononuclear hydroxamato and hydroximato complexes of iron(iii) based on the tris-(2-pyridylmethyl)amine ligand

Magnetic properties of iron(III) complex with 1,5-bis(N-methylaceto-hydroxamic acid) derivative

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