Nickel(II), copper(II) and zinc(II) complexes of 1,1,1-tris(aminomethyl)propane. A calculation procedure of stepwise formation constants and their standard errors from the Values Obtained for the Cumulative Equilibria

Michelon, Marcelo Dall'Onder; Sabatini, A.; Vacca, Alberto

doi:10.1016/s0020-1693(00)95688-3

Cited by 62 publications

(4 citation statements)

References 13 publications

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“…Potentiometric measurements were carried out in solutions of 0.15 M NaClO 4 (C. Erba ACS grade) and purified according to a procedure described earlier . Standardized CO 2 -free solutions of NaOH, used in the potentiometric titrations, were prepared by following the procedure described . The potentiometric titrations were carried out by using equipment (potentiometer, buret, stirrer, cell microcomputer, etc.)…”

Section: Methodsmentioning

confidence: 99%

Design of Ligands That Stabilize Cu(I) and Shift the Reduction Potential of the Cu^II/I Couple Cathodically in Aqueous Solutions

et al. 1999

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The ligands R(2)NCH(2)CH(2)N(R)CH(2)CH(2)N(R)CH(2)CH=CH(2), where R = H, CH(3), were synthesized. The stability constants of their complexes with Cu(II) and Cu(I) in aqueous solutions were determined. Both ligands stabilize Cu(I) in aqueous solutions, though the reduction potentials of both (CuL(i)())(2+/+) couples are shifted cathodically in comparison to the Cu(2+/+)(aq) couple. These properties indicate that these complexes should be good catalysts for a variety of processes that are catalyzed by Cu(I).

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Section: Methodsmentioning

confidence: 99%

Design of Ligands That Stabilize Cu(I) and Shift the Reduction Potential of the Cu^II/I Couple Cathodically in Aqueous Solutions

et al. 1999

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“…The reference electrode was a Ag/AgCl electrode in saturated KCl solution. The glass electrode was calibrated as a hydrogen ion concentration probe by titration of well-known amounts of HCl with CO 2 -free NaOH solutions and determination of the equivalent point by Gran's method, which gives the standard potential, E °‘, and the ionic product of water (p K w = 13.73(1)). The computer program HYPERQUAD was used to calculate the protonation and stability constants, and the DISPO program was used to obtain the distribution diagrams.…”

Section: Methodsmentioning

confidence: 99%

Synthesis and Protonation Behavior of 26-Membered Oxaaza and Polyaza Macrocycles Containing Two Heteroaromatic Units of 3,5-Disubstituted Pyrazole or 1-Benzylpyrazole. A Potentiometric and¹H and¹³C NMR Study

et al. 1999

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The synthesis and acid−base behavior of two series of 26-membered dioxatetraamine and hexaamine heterocyclophanes containing two nuclei of either pyrazole (4a and 6a) or 1-benzylpyrazole (4b and 6b), respectively, are reported. Dipodal (2 + 2) condensations of 3,5-pyrazoledicarbaldehyde 2a or its 1-benzyl derivative 2b with 1,5-diamino-3-oxapentane afford in both cases the stable Schiff bases 3a,b in 90% yield, which after reduction with NaBH4 gave 4a,b in 75% and 84% yield, respectively. Condensation of 2a with diethylenetriamine leads to a complex mixture containing imidazolidine isomers, which was reduced in situ to afford 6a in 30% yield. Condensation of 2b with the same amine gave the stable diimidazolidine derivative 5b, which after crystallization was isolated as a pure compound in 80% yield and fully identified from analytical and 1H and 13C NMR data as a constitutional isomer with both imidazolidine rings located at the side of the pyrazole closer to the benzylic substituents. Reduction of 5b with NaBH4 afforded the polyamine 6b in 86% yield. Protonation constants of 4a,b and 6a,b have been determined by potentiometric methods in the pH 2−11 range, and their protonation sequences were established by a 1H and 13C NMR study in D2O at variable pH. For each compound, the number of protonation constants equals the number of nitrogens in the side chains. In the pH range studied, the pyrazole rings are not involved in protonation or deprotonation processes.

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“…All the measurements were carried out in either 0.15 mol dm -3 NaClO 4 or 0.15 mol dm -3 NaCl. CO 2 -free NaOH solutions and HCl or HClO 4 solutions were prepared following the procedure reported in ref .…”

Section: Methodsmentioning

confidence: 99%

Thermodynamic and Steady-State Fluorescence Emission Studies on Metal Complexes of Receptors Containing Benzene Subunits

et al. 1998

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The thermodynamic properties of the Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), and Pb(2+) complexes of a family of N,N'-dibenzylated open-chain polyamines are described. For comparison, similar studies are reported for polyazacyclophane macrocyclic receptors containing an aromatic subunit linking the ends of a polyamine bridge. The metal complexes of the dibenzylated ligands show lower stability constants than those reported for related nonbenzylated open-chain polyamines. On the other hand, the stability constants of these complexes are clearly higher than those found for complexes of polyazacyclophane macrocycles containing a single para-substituted benzene spacer interrupting saturated polyamine bridges. All the studied complexes follow the Irving-Williams stability order. The crystal structure of [Cu(L7)(H(2)O)](ClO(4))(2)( )()(L7 = 1-benzyl-1,5,8,12-tetrazadodecane) shows a very strongly axially distorted square planar coordination geometry for Cu(2+). Crystals of [Cu(L7)(H(2)O)](ClO(4))(2)()()(C(15)H(24)Cl(2)CuN(4)O(9)) are orthorhombic, space group P2(1)2(1)2(1), with a = 7.586(1) Å, b = 10.715(3) Å, and c = 28.13(2) Å, Z = 4, R(1) = 0.0572, and wR(2) = 0.1570. Steady-state fluorescence emission studies performed on the Cu(2+) and Zn(2+) complexes show that, while none of the Cu(2+) complexes is emissive (CHEQ effect), fluorescence emission is observed for those Zn(2+) complexes with all the nitrogen donors either protonated or coordinated to the metal ions (CHEF effect). The composition of the frontier molecular orbitals of the free-ligands and of the Cu(2+) and Zn(2+) complexes supports this behavior. The use of these water-soluble ligands as chemosensors by means of enhancement or quenching of the fluorescence emission is also discussed.

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Nickel(II), copper(II) and zinc(II) complexes of 1,1,1-tris(aminomethyl)propane. A calculation procedure of stepwise formation constants and their standard errors from the Values Obtained for the Cumulative Equilibria

Cited by 62 publications

References 13 publications

Design of Ligands That Stabilize Cu(I) and Shift the Reduction Potential of the Cu^II/I Couple Cathodically in Aqueous Solutions

Design of Ligands That Stabilize Cu(I) and Shift the Reduction Potential of the Cu^II/I Couple Cathodically in Aqueous Solutions

Synthesis and Protonation Behavior of 26-Membered Oxaaza and Polyaza Macrocycles Containing Two Heteroaromatic Units of 3,5-Disubstituted Pyrazole or 1-Benzylpyrazole. A Potentiometric and¹H and¹³C NMR Study

Thermodynamic and Steady-State Fluorescence Emission Studies on Metal Complexes of Receptors Containing Benzene Subunits

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Nickel(II), copper(II) and zinc(II) complexes of 1,1,1-tris(aminomethyl)propane. A calculation procedure of stepwise formation constants and their standard errors from the Values Obtained for the Cumulative Equilibria

Cited by 62 publications

References 13 publications

Design of Ligands That Stabilize Cu(I) and Shift the Reduction Potential of the CuII/I Couple Cathodically in Aqueous Solutions

Design of Ligands That Stabilize Cu(I) and Shift the Reduction Potential of the CuII/I Couple Cathodically in Aqueous Solutions

Synthesis and Protonation Behavior of 26-Membered Oxaaza and Polyaza Macrocycles Containing Two Heteroaromatic Units of 3,5-Disubstituted Pyrazole or 1-Benzylpyrazole. A Potentiometric and1H and13C NMR Study

Thermodynamic and Steady-State Fluorescence Emission Studies on Metal Complexes of Receptors Containing Benzene Subunits

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Design of Ligands That Stabilize Cu(I) and Shift the Reduction Potential of the Cu^II/I Couple Cathodically in Aqueous Solutions

Design of Ligands That Stabilize Cu(I) and Shift the Reduction Potential of the Cu^II/I Couple Cathodically in Aqueous Solutions

Synthesis and Protonation Behavior of 26-Membered Oxaaza and Polyaza Macrocycles Containing Two Heteroaromatic Units of 3,5-Disubstituted Pyrazole or 1-Benzylpyrazole. A Potentiometric and¹H and¹³C NMR Study