Potentiometric titration study of two novel polydenate ligands and investigations of their complexes

Two novel linear polyamine ligands, N,N'-bis-(2-(N''-2-hydroxyl-5-bromobenzyl)aminoethyl) malondiamide (L1) and N,N'-bis-(3-(N''-2-hydroxyl-5-bromobenzyl)aminopropyl) malondiamide (L2), have been synthesized and fully characterized by elemental analysis (1H NMR and IR spectroscopy) (Fig. 1). The binding ability of ligands L1 and L2 to metal ions such as Cu(II), Zn(II), Co(II), Mn(II), Mg(II), and Ca(II) has been investigated by the potentiometric method in 1,4-dioxanewater (v/v = 15:100) and KNO3 (0.1 mol dm3) at 25.0°C. In view of the linear structures of L1 and L2, binuclear metal complexes can be formed in solution by controlling Cu(II)-5-substituted o-phenanthroline (Rphen, R = CH3, H, Cl, NO2):L to a 2:1 molar ratio, whereas the mononuclear metal complexes form at molar ratio M(II):L of 1:1, where M(II) is Cu(II), Zn(II), Co(II), Mn(II), Mg(II), and Ca(II). The stability constants of metal complexes have been determined and further discussed. In addition, two manganic complexes have been synthesized and IR and electronic spectra showed their coordination nature.Key words: linear polyamine ligand, 5-substituted o-phenanthroline, mononuclear and binuclear metal complex, stability, spectrum.

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Synthesis, Spectroscopic Properties, and Crystal Structure of the Oxonium Acid [H(OEt2)2]+[Ti2Cl9]–

Zeitschrift für Naturforschung B ◽

10.1515/znb-2003-0805 ◽

2003 ◽

Vol 58 (8) ◽

pp. 745-750 ◽

Cited By ~ 5

Author(s):

Stefan Rannabauer ◽

Tassilo Habereder ◽

Heinrich Nöth ◽

Wolfgang Schnick

Keyword(s):

Crystal Structure ◽

Ir Spectroscopy ◽

Single Crystals ◽

Nmr Spectra ◽

Spectroscopic Properties ◽

Partial Hydrolysis ◽

Distorted Tetrahedron ◽

Methyl Carbon ◽

H Nmr ◽

The Stability

The oxonium acid [H(OEt2)2]+[Ti2Cl9]− (1) was obtained by the reaction of TiCl4 with Et2O in n-pentane and subsequent partial hydrolysis. Suitable single crystals of 1 were obtained by sublimation at 5° C ([H(OEt2)2]+[Ti2Cl9]−, P212121 (no. 19), Z = 4, a = 1101.08(8), b = 1328.4(2), c = 1525.0(2) pm, T = 193(2) K, 4489 independent reflections, 197 parameters, R1 = 0.049). The cation is made up from two independent Et2O molecules and one disordered proton on two split positions. Both ether molecules exhibit a W form, and their molecular planes include an angle of 74.1(7)°. Thus a distorted tetrahedron is formed by the four methyl carbon atoms of the two ether molecules. The distance O···O amounts to 237.7(1) pm. The proton of the cation was characterized both by 1H NMR (CDCl3, T = 23 °C: δ = 11.7 ppm, w1/2 = 100 Hz) and IR spectroscopy (3120 cm−1, ν vbr). The [Ti2Cl9]− ion consists of two face sharing octahedra. 47Ti and 49Ti NMR spectra were recorded in solution (CH2Cl2, T = 23 °C: δ 49Ti = 137 ppm, w1/2 = 175 Hz; δ 47Ti = −124 ppm, w1/2 = 250 Hz). The absence of a signal for TiCl4 at δ 49Ti = 0 ppm indicates the stability of the dinuclear anion in solution.

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Host–guest interaction of cucurbit[8]uril with oroxin A and its effect on the properties of oroxin A

Beilstein Journal of Organic Chemistry ◽

10.3762/bjoc.16.194 ◽

2020 ◽

Vol 16 ◽

pp. 2332-2337

Author(s):

Zhishu Zeng ◽

Jun Xie ◽

Guangyan Luo ◽

Zhu Tao ◽

Qianjun Zhang

Keyword(s):

Ir Spectroscopy ◽

Antioxidant Capacity ◽

Gastric Juice ◽

Binding Constant ◽

Inclusion Compound ◽

Molar Ratio ◽

Cumulative Release ◽

H Nmr

In this study, we investigated the host–guest interactions between oroxin A (OA) and cucurbit[8]uril (Q[8]) using 1H NMR, MS, UV–vis and IR spectroscopy. The results showed that OA and Q[8] formed an inclusion compound (OA@Q[8]) with a molar ratio of 1:1 and a binding constant of 1.299 × 107 L·mol−1. In addition, the effect of Q[8] on the properties of OA was investigated through comparative experiments. The solubility of OA in water increased 22.47-fold when the concentration of Q[8] was 1 × 10−4 mol·L−1. Q[8] hardly affected the antioxidant capacity of OA, while the cumulative release of OA in gastric juice increased 2.3-fold after forming the inclusion compound with Q[8].

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Fletcher–Powell minimization of analytical potentiometric data by microcomputer: application to the Cu(II) complexes of biological polyamines

Canadian Journal of Chemistry ◽

10.1139/v85-515 ◽

1985 ◽

Vol 63 (11) ◽

pp. 3122-3128 ◽

Cited By ~ 24

Author(s):

Douglas M. Templeton ◽

Bibudhendra Sarkar

Keyword(s):

Biological Activity ◽

Metal Complex ◽

Stability Constants ◽

Speciation Analysis ◽

Complex Stability ◽

Minimization Algorithm ◽

The Stability ◽

Best Fit ◽

Complex Stability Constants ◽

Potentiometric Data

The Fletcher–Powell minimization algorithm has been successfully implemented for the extraction of metal complex stability constants from analytical potentiometric data. The procedure has been adapted to run on a microcomputer with acceptable execution times, and several strategies are employed to speed convergence and avoid false minima. This allows economical minimization for a large number of models of speciation, and improves the reliability of the proposed best fit by encouraging the checking of more models than previously possible. The Ni(II)–glycine system has been analyzed and excellent agreement with the stability constants of an earlier multi-laboratory study has been attained. The system proves useful in the evaluation of both analytical and computational methods. The procedure has also been used for speciation analysis of the Cu(II) complexes of the growth regulating polyamines, spermine, and spermidine. Both systems form fully deprotonated complexes at physiological pH, which are relevant to their biological activity.

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The Cucurbit[8]uril effect on the properties of Oroxin A

10.3762/bxiv.2020.81.v1 ◽

2020 ◽

Author(s):

Zhishu Zeng ◽

Jun Xie ◽

Guangyan Luo ◽

Zhu Tao ◽

Qianjun Zhang

Keyword(s):

Ir Spectroscopy ◽

Antioxidant Capacity ◽

Gastric Juice ◽

Binding Constant ◽

Inclusion Compound ◽

Molar Ratio ◽

Cumulative Release ◽

H Nmr

In this study, we investigated host–guest interactions between Oroxin A (OA) and cucurbit[8]uril (Q[8]) using 1H NMR, MS, UV-Vis and IR spectroscopy. The results showed that OA and Q[8] formed an inclusion compound (OA@Q[8]) with a molar ratio of 1:1 and a binding constant of 1.299 × 107 L·mol−1. In addition, the effect of Q[8] on the properties of OA was investigated through comparative experiments. The solubility of OA in water increased 22.47-fold when the concentration of Q[8] was 1 × 10−4 mol·L−1. Q[8] hardly affected the antioxidant capacity of OA, while the cumulative release of OA in gastric juice increased 2.3-fold after forming the inclusion compound with Q[8].

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Synthesis and Characterization of New Lead(II) and Organotin(IV) Complexes of Schiff Bases Derived from Histidine and Methionine

International Journal of Inorganic Chemistry ◽

10.1155/2012/568797 ◽

2012 ◽

Vol 2012 ◽

pp. 1-7 ◽

Cited By ~ 5

Author(s):

Har Lal Singh ◽

J. B. Singh

Keyword(s):

Schiff Base ◽

Metal Complexes ◽

Analytical Data ◽

Molar Conductance ◽

Molar Ratio ◽

Azomethine Nitrogen ◽

Spectral Studies ◽

Tetrahedral Geometry ◽

H Nmr ◽

Carboxylate Oxygen

New Schiff base (HL) ligand is prepared via condensation of isatins and amino acids in 1:1 molar ratio. Metal complexes are prepared and characterized by elemental analysis, molar conductance, electronic, infrared, and multinuclear magnetic resonance (1H NMR, 13C NMR, and 119Sn NMR). The analytical data showed that the ligand acts as bidentate toward metal ions via azomethine nitrogen and carboxylate oxygen by a stoichiometric reaction of metal : ligand (1 : 2) to from metal complexes (Pb(II)(L)2 and Bu2Sn(L)2, where L is the Schiff base ligands of histidine and methionine). The conductivity values between 15 and 25 Ω−1cm2 mol−1 in DMF imply the presence of nonelectrolyte species. On the basis of the above spectral studies, distorted octahedral and tetrahedral geometry have been proposed for the resulting organotin(IV) and lead(II) complexes.

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Kinetic and spectroscopic studies on α- and β-cyclodextrin rotaxanes with (µ-N,N′- bis(4-pyridinylmethylene)-α,ω-alkanediimine)bis[pentacyanoferrate(II)] threads

Canadian Journal of Chemistry ◽

10.1139/v05-019 ◽

2005 ◽

Vol 83 (3) ◽

pp. 195-201 ◽

Cited By ~ 4

Author(s):

Victor X Jin ◽

Donal H Macartney ◽

Erwin Buncel

Keyword(s):

Chemical Shift ◽

Metal Complexes ◽

Key Words ◽

Rate Constants ◽

Self Assembly ◽

Spectroscopic Studies ◽

Ligand Substitution ◽

H Nmr ◽

End Groups ◽

The Stability

[2]Pseudorotaxanes have been prepared by threading N,N′-bis(4-pyridinylmethylene)-1,2-ethanediimine (L2), -1,4-butanediimine (L4), and -1,6-hexanediimine (L6) ligands through α-cyclodextrin (α-CD) and β-cyclodextrin (β-CD), and have subsequently been converted to the corresponding [2]rotaxane species by coordinating bulky [Fe(CN)5]3 end groups. The stability constants for the [2]pseudorotaxanes were determined by 1H NMR chemical shift titrations and increase with the polymethylene chain length n. The rate constants for both the formation of the [Fe(CN)5(Ln)]3 complexes from the [Fe(CN)5OH2]3 ion and Ln, and the rate constants for the dissociation of Ln from the metal complexes, exhibit significant diminutions in the presence of α- and β-CD, owing to inclusions of the free and coordinated ligands, respectively. The lability of the iron(II)pyridine bonds also permits the spontaneous self-assembly of the [2]rotaxane upon the addition of cyclodextrin to the iron dimer complexes. The mechanism for this process involves the rate-determining dissociation of a [Fe(CN)5]3 unit from [(NC)5Fe(Ln)Fe(CN)5]6, followed by CD inclusion of the Ln ligand to form a semirotaxane, and subsequent recomplexation by the [Fe(CN)5OH2]3 ion. Key words: cyclodextrins, rotaxanes, pentacyanoferrate(II), ligand substitution, kinetics.

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Synthesis and physical studies of pyridine and imidazole containing tridentate metal binding ligands

Canadian Journal of Chemistry ◽

10.1139/v80-141 ◽

1980 ◽

Vol 58 (9) ◽

pp. 889-901 ◽

Cited By ~ 31

Author(s):

R. S. Brown ◽

J. Huguet

Keyword(s):

Carbonic Anhydrase ◽

Metal Complex ◽

Metal Binding ◽

Nmr Studies ◽

Binding Ability ◽

Tridentate Ligands ◽

H Nmr ◽

Metal Ratio ◽

Imidazole Ligands ◽

Metal Binding Ability

Several tridentate ligands incorporating pyridine and substituted imidazoles were prepared and their physical properties studied as models for the enzyme carbonic anhydrase (CA). The H+ and M2+ binding abilities (pKa and [Formula: see text]) were determined. In the case of the imidazole ligands, N-methylation reduces the metal binding ability of the ligand by some 3–4 [Formula: see text] units over the analogues in which the imidazole has N—H. 1H-nmr studies of the simple ligands as a function of [Zn2+] show that the ligands are bound symmetrically as 1:1 and 2:1 complexes depending upon the ligand/metal ratio. Increasing the steric bulk of the ligands by introduction of 4,5-diisopropyl substituents on the imidazole inhibits the 2:1 (ligand/metal) complex. Titration experiments of several ligands bound to equimolar Zn2+ and Co2+ are described and analysed.

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Metal complexes of propane-1,2,3-triamine. Potentiometric and calorimetric investigations

Canadian Journal of Chemistry ◽

10.1139/v97-025 ◽

1997 ◽

Vol 75 (2) ◽

pp. 212-219 ◽

Cited By ~ 2

Author(s):

Renzo Cini ◽

Antonio Sabatini ◽

Alberto Vacca ◽

Fabrizio Zanobini

Keyword(s):

Metal Complexes ◽

Stability Constants ◽

Metal Ion ◽

Molar Ratio ◽

Thermodynamic Quantities ◽

Nickel Copper ◽

Formation Enthalpies ◽

The Stability ◽

Ph Range ◽

Calorimetric Investigations

The complexes formed by the ions Co2+, Ni2+, Cu2+, and Zn2+ with the ligand propane-1,2,3-triamine (L1) in 0.15 mol dm−3 aqueous NaCl at 25 °C have been studied by potentiometry and calorimetry (ligand to metal molar ratio, 1–3; pH range from 3.0 to 6.5–11.0). Stability constants have been obtained from potentiometric data by means of the least-squares program HYPERQUAD for the following species: [M(L1)]2+ and [MH(L1)]3+ for all four metal cations; [M(L1)2]2+ and [MH(L1)2]3+ for Ni2+, Cu2+, and Zn2+; [MH2(L1)2]4+ for Ni2+ and Cu2+; and [M(OH)(L1)]+ for Cu2+ only. Stabilities increase in the order Zn < Co < Ni < Cu. The complexes of L1 have approximately the same stability as the corresponding ones formed by the related triamines 2-methyl (2-methylamine) propane-1,3-diamine (L3) and 2-ethyl (2-methylamine)propane-1,3-diamine (L4). The stability constants have been used to obtain, from the calorimetric titration experiments, the formation enthalpies of all the metal complexes except those for cobalt(II) as well as the corresponding entropy changes. The thermodynamic quantities are compared with the corresponding values previously found for L3, in order to derive information about the coordination ability of the ligand. The analysis suggests that the unprotonated ligand forms a fac-tridentate complex in most cases, but for some species, such as [Cu(L1)2]2+, [CuH(L1)2]3+, and [Zn(L1)]2+, the thermodynamic quantities indicate that at least one of the nitrogen atoms of the triamine is either loosely bonded or not coordinated to the metal ion. A gas-phase molecular mechanics analysis shows that the strain energies of the fac-[Co(L1)2]2+ and -[Ni(L1)2]2+ symmetrical (s) and unsymmetrical (u) isomers are very similar. If the same solvation energy is assumed for the two isomers, each isomer will be present in roughly equal amounts in solution. Keywords: propane-1,2,3-triamine, potentiometry, calorimetry, complexation, cobalt, nickel, copper, zinc.

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