Complexes of water-soluble hexadentate schiff base ligands with a number of metal ions

Evans, Denis J.; Jakubovic, David A.

doi:10.1016/s0277-5387(00)80700-7

Cited by 21 publications

(5 citation statements)

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“…Although no attempt was made to determine the stability constants of the Al complexes, they should be much lower than the stability constants of the Ga and In complexes. This is actually corroborated by the pM values of the Al and Ga complexes with the Schiff base analog of H 2 bad . The Ga Schiff base complex pM value was ∼9 units higher than that for the corresponding Al complex.…”

Section: Resultssupporting

confidence: 57%

“…The gallium linear amine phenol complexes (those of Sbad 4- and Sbadd 4- ) were 3 orders of magnitude more stable than the corresponding indium analogs. This selectivity for gallium is expected on the basis of the information available for ligands containing only aliphatic amine and phenolate donor atomshydroxybenzyl and hydroxypyridyl derivatives of triazacyclononane, the hexadentate Schiff base saltames, and the tripodal N 3 O 3 amine phenols based on the amines tap and tame . This is not surprising given that Hancock and Martell have shown that the affinity of amines for gallium and indium is of the same order of magnitude, and Martell and co-workers have demonstrated that the 2-oxybenzyl group favors complexation with gallium over indium .…”

Section: Resultsmentioning

confidence: 95%

“…This is not surprising given that Hancock and Martell have shown that the affinity of amines for gallium and indium is of the same order of magnitude, and Martell and co-workers have demonstrated that the 2-oxybenzyl group favors complexation with gallium over indium . The selectivity of Sbad 4- and Sbadd 4- for gallium is much less than in the cited examples. − One obvious difference is that the prior literature on gallium and indium amine phenol complexes involved ligands with N 3 O 3 donor sets, not the N 4 O 2 donor set in Sbad 4- and Sbadd 4- . Substituting an amine for a phenolate, and hence “softening” the donor set, has muted the selectivity for gallium over indium.…”

Section: Resultsmentioning

confidence: 96%

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Selectivity of Potentially Hexadentate Amine Phenols for Ga³⁺ and In³⁺ in Aqueous Solution^,

et al. 1996

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A new series of linear N4O2 amine phenols (H2 badd, H2 Brbadd, and H2 Clbadd) based on N,N‘-bis(3-aminopropyl)ethylenediamine (tnentn) were prepared and characterized by spectroscopic techniques. Monocationic hexadentate metal complexes with the tnentn-based amine phenols were obtained from the reactions of Ga3+ and In3+ with the linear amine phenol in the presence of a weak base (acetate). The molecular structure of [Ga(Brbadd)]ClO4 has been determined by X-ray crystallography; crystals of [Ga(Brbadd)][ClO4] (C22H30Br2ClGaN4O6) are orthorhombic: a = 12.462(1) Å, b = 21.835(2) Å, c = 9.961(2) Å, Z = 4, space group P212121. The structure was solved by the Patterson method and was refined by full-matrix least-squares procedures to R = 0.031 (R w = 0.029) for 1924 reflections with I ≥ 3σ(I). The Ga3+ ion is coordinated in a distorted octahedral geometry by an N4O2 donor atom set. The four nitrogen atoms of the tetraamine backbone form the equatorial plane of the octahedron, and the two phenolate oxygen atoms are coordinated trans to each other. Water-soluble 1,10-bis(2-hydroxy-5-sulfonylbenzyl)-1,4,7,10-tetraazadecane (H6 Sbad 2+), 1,12-bis(2-hydroxybenzyl-5-sulfonylbenzyl)-1,5,8,12-tetraazadodecane (H6 Sbadd 2+), and N,N‘-bis-(2-hydroxy-5-sulfonylbenzyl)-N,N‘-bis(2-methylpyridyl)ethylenediamine (H6 Sbbpen 2+) were also prepared and characterized; potentiometric titrations of these three ligands, in the absence and presence of Ga3+ and In3+, were performed to determine deprotonation constants of the ligands and the thermodynamic stabilities of Ga and In amine phenol complexes. The formation constants of the Ga3+ and In3+ complexes with Sbad 4- (Ga3+, log β = 28.33(8); In3+, log β = 24.54(2)), Sbadd 4- (Ga3+, log β = 28.27(5); In3+, log β = 24.56 (5)), and Sbbpen 4- (Ga3+, log β = 35.33(8); In3+, log β = 34.85(5)) were obtained. All six of the Ga and In hexadentate amine phenol complexes were found to be very stable in aqueous solution. With the exception of [In(Sbadd)]-, all the complexes were calculated to be thermodynamically stable with respect to demetalation by transferrin at physiological pH. The linear amine phenols showed a selectivity for Ga3+ over In3+, while the Sbbpen 4- derivative was indiscriminate in binding the Ga3+ and In3+ ions.

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Section: Resultssupporting

confidence: 57%

Section: Resultsmentioning

confidence: 95%

Section: Resultsmentioning

confidence: 96%

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Selectivity of Potentially Hexadentate Amine Phenols for Ga³⁺ and In³⁺ in Aqueous Solution^,

et al. 1996

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“…Furthermore, the Schiff base condensation reaction is rapid, is clean, and gives high yields. Although metalated Schiff base complexes generally have a low aqueous solubility, Evans and Jukubovic have studied complexes derived from the condensation of sodium 5-sulfosalicylaldehyde with various amines and determined p M values as a measure of thermodynamic stability. , One drawback to Schiff bases is that they undergo partial hydrolysis in water at the imine linkage, and this may be the source of in vivo degradation of their metal complexes. Reduction of the imine eliminates the hydrolysis problem and results in a more flexible ligand.…”

Section: Introductionmentioning

confidence: 99%

Tripodal Aminophenolate Ligand Complexes of Aluminum(III), Gallium(III), and Indium(III) in Water

Caravan

Orvig

1997

Inorg. Chem.

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Four water-soluble amine phenols have been prepared: tris(((2-hydroxy-5-sulfobenzyl)amino)ethyl)amine (H6TRNS), 1,1,1-tris(((2-hydroxy-5-sulfobenzyl)amino)methyl)ethane (H6TAMS), 1,2,3-tris((2-hydroxy-5-sulfobenzyl)amino)propane (H6TAPS), and cis,cis-1,3,5-tris((2-hydroxy-5-sulfobenzyl)amino)cyclohexane (H6TACS). Complex formation constants have been measured at 25 °C (μ = 0.16 M NaCl): log K [M(TRNS)]3- ([M(HTRNS)]2-) M = Ga 28.55 (36.90), In 29.3 (34.9); log K [M(TAMS)]3- ([M(HTAMS)]2-) M = Al 22.5 (29.3), Ga 31.83, In 28.49; log K [M(TAPS)]3- ([M(HTAPS)]2-) M = Al 22.8 (29.0), Ga 31.54 (35.15), In 27.56 (31.93). The order of stability is Ga(III) > In(III) > Al(III) for H6TAMS and H6TAPS, while for H6TRNS it is Ga(III) ≈ In(III) > Al(III). The solution structures of the complexes have been probed by multinuclear NMR (1H, 13C, 27Al, 71Ga, 115In) and UV spectroscopic studies, and these solution structures are compared with solid state structures for analogous complexes. The 1H NMR spectrum in D2O establishes TAPS to be preorganized for metal ion binding. H6TACS exists in the wrong conformation for metal ion binding, and this results in slow complexation kinetics and relatively weaker binding.

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“…SCHEME 2 Reactivity of complex (1) against protic ligands. iminophosphine ligand coordinated to Pd and shifted to lower frequencies than in the free ligand [11,21,23], together with the respective absorptions of the incoming ligands.…”

Section: Resultsmentioning

confidence: 95%

New Palladium(II) Complexes with a Tridentate PNO Ligand

Sánchez

Momblona

Serrano

et al. 2002

Journal of Coordination Chemistry

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Complexes of water-soluble hexadentate schiff base ligands with a number of metal ions

Cited by 21 publications

References 12 publications

Selectivity of Potentially Hexadentate Amine Phenols for Ga³⁺ and In³⁺ in Aqueous Solution^,

Selectivity of Potentially Hexadentate Amine Phenols for Ga³⁺ and In³⁺ in Aqueous Solution^,

Tripodal Aminophenolate Ligand Complexes of Aluminum(III), Gallium(III), and Indium(III) in Water

New Palladium(II) Complexes with a Tridentate PNO Ligand

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Complexes of water-soluble hexadentate schiff base ligands with a number of metal ions

Cited by 21 publications

References 12 publications

Selectivity of Potentially Hexadentate Amine Phenols for Ga3+ and In3+ in Aqueous Solution,

Selectivity of Potentially Hexadentate Amine Phenols for Ga3+ and In3+ in Aqueous Solution,

Tripodal Aminophenolate Ligand Complexes of Aluminum(III), Gallium(III), and Indium(III) in Water

New Palladium(II) Complexes with a Tridentate PNO Ligand

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Selectivity of Potentially Hexadentate Amine Phenols for Ga³⁺ and In³⁺ in Aqueous Solution^,

Selectivity of Potentially Hexadentate Amine Phenols for Ga³⁺ and In³⁺ in Aqueous Solution^,