scholarly journals DOTA analogues with a phosphinate-iminodiacetate pendant arm: modification of the complex formation rate with a strongly chelating pendant

2017 ◽  
Vol 46 (31) ◽  
pp. 10484-10497 ◽  
Author(s):  
Soňa Procházková ◽  
Vojtěch Kubíček ◽  
Zuzana Böhmová ◽  
Kateřina Holá ◽  
Jan Kotek ◽  
...  
Keyword(s):  
Complex Formation ◽  
Metal Ion ◽  
Formation Rate ◽  
Macrocyclic Ligand ◽  
Pendant Arm

The formation of highly stable out-of-cage complexes slows down the transfer of the metal ion into the cavity of the macrocyclic ligand.

scholarly journals Sensing Zn2+ in Aqueous Solution with a Fluorescent Scorpiand Macrocyclic Ligand Decorated with an Anthracene Bearing Tail

Molecules ◽  
2020 ◽  
Vol 25 (6) ◽  
pp. 1355 ◽  
Author(s):  
Matteo Savastano ◽  
Matteo Fiaschi ◽  
Giovanni Ferraro ◽  
Paola Gratteri ◽  
Palma Mariani ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Complex Formation ◽  
Metal Ion ◽  
Equilibrium Constants ◽  
Macrocyclic Ligand ◽  
Fluorescence Emission ◽  
Zinc Complexes ◽  
Large Excess ◽  
Macrocyclic Ring ◽  
Ph Range

Synthesis of the new scorpiand ligand L composed of a [9]aneN3 macrocyclic ring bearing a CH2CH2NHCH2-anthracene tail is reported. L forms both cation (Zn2+) and anion (phosphate, benzoate) complexes. In addition, the zinc complexes of L bind these anions. The equilibrium constants for ligand protonation and complex formation were determined in 0.1 M NaCl aqueous solution at 298.1 ± 0.1 K by means of potentiometric (pH-metric) titrations. pH Controlled coordination/detachment of the ligand tail to Zn2+ switch on and off the fluorescence emission from the anthracene fluorophore. Accordingly, L is able to sense Zn2+ in the pH range 6–10 down to nM concentrations of the metal ion. L can efficiently sense Zn2+ even in the presence of large excess of coordinating anions, such as cyanide, sulphide, phosphate and benzoate, despite their ability to bind the metal ion.

Komplexbildung und Ligandenfluktuation im System Co (II) / [18] Krone-6 / Complex Formation and Ligand Fluctuation in the System Co(II)/[18]crown-6

1983 ◽  
Vol 38 (8) ◽  
pp. 934-937 ◽  
Author(s):  
Franz L. Dickert ◽  
Walter Gumbrecht
Keyword(s):  
Nmr Spectroscopy ◽  
Complex Formation ◽  
Crown Ether ◽  
Time Scale ◽  
Metal Ion ◽  
Macrocyclic Ligand ◽  
Mixed Complex ◽  
Dissociation Reaction ◽  
C Nmr

The ligand properties of [18]crown-6 towards Co(II) ions were studied by 1H and 13C NMR spectroscopy in nitromethane and nitromethane/methanol. The complexes [Co([18]crown-6)]++ and mer-[Co([18]crown-6)(CH3OH)3]++ which were detected in solu­tion show ligand fluctuations on the NMR time scale. For the mixed complex a crown ether rotation occurs. Additionally, a synchronous process between the movement of the macrocyclic ligand and the dissociation reaction of methanol from the metal ion is observed.

Anion effect on alkali ion-crown complex formation in a moderately concentrated solutions: A sensitive probe of hidden interionic interactions operating in dissociating protic solvents

1990 ◽  
Vol 55 (5) ◽  
pp. 1149-1161
Author(s):  
Jiří Závada ◽  
Václav Pechanec ◽  
Oldřich Kocián
Keyword(s):  
Hydrogen Bond ◽  
Complex Formation ◽  
Charge Density ◽  
Macrocyclic Ligand ◽  
Simple Explanation ◽  
Anion Effect ◽  
Protic Solvents ◽  
The Individual ◽  
Alkali Salts ◽  
Alkali Ion

A powerful anion effect destabilizing alkali ion-crown complex formation has been found to operate in moderately concentrated protic (H2O, CH3OH, C2H5OH) solution, following the order HO- > AcO- > Cl- > Br- > NO3- > I- > NCS-. Evidence is provided that the observed effect does not originate from ion-pairing. A simple explanation is provided in terms of concordant hydrogen bond bridges of exalted stability between the gegenions, M+···OR-H···(OR-H)n···OR-H···A-. It is proposed that encapsulation of alkali ion by the macrocyclic ligand leads to a dissipation of the cation charge density destroying its ability to participate in the hydrogen bond bridge. An opposition against the alkali ion-crown complex formation arises accordingly in the solution in dependence on strength of the hydrogen bridge; for a given cation, the hydrogen bond strength increases with increasing anion charge density from NCS- to HO-(RO-). It is pointed out, at the same time, that the observed anion effect does not correlate with the known values of activity coefficients of the individual alkali salts which are almost insensitive to anion variation under the investigated conditions. As a resolution of the apparent paradoxon it is proposed that, in absence of the macrocyclic ligand, the stabilizing (concordant) bonding between the gegenions is nearly balanced by a destabilizing (discordant) hydrogen bonding between the ions of same charge (co-ions). Intrinsic differences among the individual salts are thus submerged in protic solvents and become apparent only when the concordant bonding is suppressed in the alkali ion-crown complex formation.

Protonation effects on dynamic flux properties of aqueous metal complexes

2009 ◽  
Vol 74 (10) ◽  
pp. 1543-1557 ◽  
Author(s):  
Herman P. Van Leeuwen ◽  
Raewyn M. Town
Keyword(s):  
Complex Formation ◽  
Metal Ion ◽  
Good Description ◽  
Minor Component ◽  
Outer Sphere ◽  
Metal Species ◽  
Central Metal ◽  
Inner Sphere ◽  
A Minor ◽  
Protonated Ligand

The degree of (de)protonation of aqueous metal species has significant consequences for the kinetics of complex formation/dissociation. All protonated forms of both the ligand and the hydrated central metal ion contribute to the rate of complex formation to an extent weighted by the pertaining outer-sphere stabilities. Likewise, the lifetime of the uncomplexed metal is determined by all the various protonated ligand species. Therefore, the interfacial reaction layer thickness, μ, and the ensuing kinetic flux, Jkin, are more involved than in the conventional case. All inner-sphere complexes contribute to the overall rate of dissociation, as weighted by their respective rate constants for dissociation, kd. The presence of inner-sphere deprotonated H2O, or of outer-sphere protonated ligand, generally has a great impact on kd of the inner-sphere complex. Consequently, the overall flux can be dominated by a species that is a minor component of the bulk speciation. The concepts are shown to provide a good description of experimental stripping chronopotentiometric data for several protonated metal–ligand systems.

scholarly journals Synthesis and characterization of Ni(II), Cu(II) and Co(III) complexes with polyamine-containing macrocycles bearing an aminoethyl pendant arm

2004 ◽  
Vol 69 (8-9) ◽  
pp. 641-649 ◽  
Author(s):  
Fouzia Rafat ◽  
M.Y. Siddiqi ◽  
K.S. Siddiqi
Keyword(s):  
Metal Ion ◽  
Magnetic Moments ◽  
Carbon Chain ◽  
Macrocyclic Complex ◽  
Synthesis And Characterization ◽  
Epr Spectrum ◽  
Pendant Arm ◽  
Octahedral Environment ◽  
Electrical Conductivities

Reaction of [M(ppn)2]X2 (where M = Cu(II), Ni(II), Co(II) and ppn = 1,3-diaminopropane) with formaldehyde and ethylenediamine in methanol results in the ready formation of a 16-membered macrocyclic complex. The complexes were characterized by elemental analysis, IR, EPR, electronic spectral data magnetic moments and conductance measurements. The Cu(II), Ni(II) and Co(III) complexes are coordinated axially with both pendant groups of the hexadentate macrocycle. These pendant donors are attached to the macrocycle by a carbon chain. The electrical conductivities of the Cu(II) and Ni(II) chelates indicated them to be 1:2 electrolytes whilst those of Co(III) is a 1:3 electrolyte in DMSO. The EPR spectrum of the copper complex exhibited G at 3.66, which indicates a considerable exchange interaction in the complex. Spectroscopic evidence suggests that in all of the complexes the metal ion is in an octahedral environment.

SYNTHESIS, SPECTRAL STUDIES, STRUCTURAL EVALUATION AND ANTIMICROBIAL ACTIVITY OF SOME NOVEL C R(III) COMPLEXES CONTAINING TETRADENTATE MACROCYCLIC LIGANDS

INDIAN DRUGS ◽  
2017 ◽  
Vol 54 (06) ◽  
pp. 20-29
Author(s):  
S Shukla ◽  
◽  
S. Gautam ◽  
S Chandra ◽  
A. Kumar
Keyword(s):  
Metal Complexes ◽  
Metal Ion ◽  
Metal Salt ◽  
Condensation Reaction ◽  
Macrocyclic Ligand ◽  
Agar Plate ◽  
Macrocyclic Ligands ◽  
Diffusion Method ◽  
Spectral Studies ◽  
Spectral Techniques

A string of novel coordination compounds of Cr(III) complexes have been derived and characterized from the macrocyclic ligands (L 1 -L 2 ) carried out by condensation reaction between ligands and the subsequent metal salt. The chemical composition of ligand was determined by analytical and spectral techniques i.e. elemental analysis, IR and Mass spectrocopy. Spectral techniques revealed tetradentate [N 4 ] the nature of ligand and its coordination mode to metal ion through nitrogen donor atoms. Metal complexes were characterized by elemental analyses, molar conductance, magnetic susceptibility measurements, IR, electronic spectra, ePR studies. The geometry of these complexes was ascertained by molecular modelling study by using Gaussian 09 program. All metal complexes were found to exhibit octahedral geometry around the metal ion. The newly synthesized macrocyclic ligands and metal complexes were subjected for antimicrobial screening to determine the inhibition and control against tested microorganisms, bacteria ( S.lutea , S.aureus, S.albus and E.coli ) and fungi ( A.fulviceps, U . hordei, A. niger and P.catinus ) by using disc diffusion method and agar plate technique, respectively. The experimental results suggest that metal complexes exhibit enhanced inhibition zone than free macrocyclic ligand.

Adsorption of Cu2+ Metal Ions on Dithizone-Immobilized Natural Bentonite

2020 ◽  
Vol 840 ◽  
pp. 64-70
Author(s):  
Dian Mira Fadela ◽  
Mudasir Mudasir ◽  
Adhitasari Suratman
Keyword(s):  
Adsorption Isotherm ◽  
Complex Formation ◽  
Metal Ions ◽  
Electrostatic Interaction ◽  
Metal Ion ◽  
Synthesis And Characterization ◽  
Optimum Conditions ◽  
Initial Concentration ◽  
Activated Bentonite

The research of adsorption of Cu2+ metal ion on dithizone-immobilized natural bentonite (DNB) had been carried out. The experiment was begun by the activation of natural bentonite with HCl 4 M and dithizone-immobilized on activated bentonite surface. This study included synthesis and characterization of dithizone-immobilized bentonite and its application in adsorption of Cu2+ metal ions. The type of interaction occurred in the adsorption was tested by sequential desorption. The result showed that dithizone successfully immobilized on activated natural bentonite (ANB). The optimum conditions for Cu2+ metal ions adsorption using dithizone-immobilized natural bentonite are at pH 5; 0.1 g mass of adsorbent, with interaction time 60 min, and the initial concentration of ion at 80 ppm. Kinetics and adsorption isotherm studies suggest that the capacity, of the dithizone-immobilized natural bentonite in adsorbing Cu2+ metal ion is significantly improved compared to activated natural bentonite. The adsorption of Cu2+ metal ions by activated natural bentonite was through several interactions dominated by electrostatic interaction (82%). Otherwise, the interaction of dithizone-immobilized natural bentonite with Cu2+ metal ions in the sequence were dominated by the mechanism of complex formation of (75%). The result shows that the immobilization of dithizone changes the type of electrostatic interaction into complex formation.

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