Mixed Ligand Chelates Research Articles

Action of 1,10-phenanthroline transition metal chelates on P388 mouse lymphocytic leukaemic cells

1. (1)Fully coordinated 1,10-phenanthroline and 2,2′-bipyridine chelates of Ru(II) are lethal in vitro to cultured and ascites P388 mouse lymphocytic leukaemic cells; 1,10-phenanthroline chelates are generally more potent than corresponding 2,2′-bipyridine compounds, and mixed-ligand (acetylacetonato) monovalent chelates of both series are more active than the corresponding identical-ligand divalent chelates. Lethal potency is greatest for Ru(II) chelates containing highly alkylated ligands. 2. (2)Within two series of tetramethyl-1,10-phenanthroline chelates, the inert Ru(II) and Ni(II) members are less active against P388 cultured and ascites cells than the corresponding more labile chelates of Cu(II), Cd(II), Zn(II), Fe(II) and Co(II); for the ascites cells, the rank order of lethal potency of the chelates correlates reasonably well with their anticipated rank order of kinetic reactivity. 3. (3)Repeated subculture of P388 cells in the presence of a mixed-ligand Ru(II) chelate has produced a cell line that shows a stable 10-fold resistance to the chelate; the resistant cell line is selectively cross-resistant to certain Ru(II) identical and mixed-ligand chelates. 4. (4)The presence of a fluorescent Ru(II) chelate has been demonstrated at the surface and within the cytoplasm and nucleus of P388 ascites cells exposed to it either in vitro or in the mouse. 5. (5)Ru(II) and Cu(II) chelates of tetramethyl-1,10-phenanthroline do not appear to be chemotherapeutically active against P388 ascites cells in the mouse.

Use of an ion sensitive electrode in the study of the mixed ligand chelates of Th(IV) with aminopolycarboxylic acids and fluoride ions

Use of an ion sensitive electrode in the study of the mixed ligand chelates of Th(IV) with aminopolycarboxylic acids and fluoride ions

A Mössbauer study of aftereffects of Auger events in cobalt chelates with varying degree of conjugation

The electron-capture decay of a cobalt-57 atom triggers an Auger event resulting in the loss of several electrons from the molecule in which it is incorporated. The 14.4 keV Mössbauer emission conveys information regarding the chemical forms in which the daughter iron-57 is stabilized within 10−7 sec following electron capture. The electronic relaxation occurs very rapidly and several tens of eV electronic excitation energy is deposited on the molecule during charge neutralization. Emission Mössbauer spectra of cobalt-57 labeled complexes of the strong field ligands phenanthroline and ethylenediamine, namely [57Co(III)(phen)3](ClO4)3⋅2H2O, [57Co(III)(phen)2(en)]Cl3⋅H2O, [57Co(III)(phen)(en)2] (NO3)3, and [57Co(III)(en)3]Cl3 were studied. The chelate molecules possess varying degree of conjugation. The presence of strong field ligands in the chelates made it easier to identify the high spin ionic iron species Fe2+ and Fe3+, which can form only as a result of fragmentation. Molecules which have no conjugation, e.g., [57Co(III)(en)3]3+, or which possess small degree of conjugation like [57Co(III)(phen) (en)2]3+, fragment in practically 100% of the Auger events. On the other hand, the molecules of [57Co(III)(phen)2(en)]3+, which possess relatively higher degree of conjugation, escape fragmentation in about 20% of the events; while the highly conjugated molecules of [57Co(III) (phen)3]3+ seem to escape fragmentation in almost 100% of the events. One can perhaps conclude that the probability of fragmentation of a molecule as a consequence of the Auger event diminishes with higher degree of conjugation in the molecule. It is speculated that the aftereffects of the Auger event result in collective excitation of the π-electrons in a highly conjugated system. The de-excitation of the ’’plasmon’’ occurs rapidly, presumably through emission of a single electron or an energetic photon. The mixed ligand chelates, [57Co(III)(phen)2(en)]3+ and [57Co(III)(phen) (en)2]3+ show an interesting phenomenon. The cationic iron species formed as a result of fragmentation recombines with electron(s) to form an electronically excited cation, presumably 57Fe+2 which interacts with neighboring cobalt chelate molecules. The phenanthroline ligands are preferentially transferred onto the electronically excited cation forming [57Fe(III)(phen)3]3+ quite efficiently. The transfer of ligands occur in less than 10−7 sec., as is evidenced by the manifestation of the tris-phenanthroline chelate in the emission Mössbauer spectra.

Excited states of mixed ligand chelates of ruthenium(II) and rhodium(III)

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTExcited states of mixed ligand chelates of ruthenium(II) and rhodium(III)G. A. Crosby and W. H. Elfring Jr.Cite this: J. Phys. Chem. 1976, 80, 20, 2206–2211Publication Date (Print):September 1, 1976Publication History Published online1 May 2002Published inissue 1 September 1976https://doi.org/10.1021/j100561a016RIGHTS & PERMISSIONSArticle Views653Altmetric-Citations107LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (800 KB) Get e-Alerts

Polarographic study of mixed ligand complexes: cadmium-oxalate-salicylate system

The nature of mixed ligand chelates of Cd(II) with bidentate ligands like oxalic and salicylic acids has been investigated by a polarographic technique. It is observed that Cd(II) forms three complex species with oxalic acid with the respective stability constants: log β 10 = 2·78 ± 0·15, log β 20 = 4·00 ± 0·20 and log β 30 = 5·20 ± 0·15 and two complexes with salicylic acid with log β 01 = 0·40 and log β 02 = 1·18. Evidence is given for the formation of mixed ligand chelates having 1:1:1 and 1:2:1 ratios of Cd(II):Ox:sal. The absence of Cd(Ox) (sal) 2 is inferred from the negative value of its stability constant. The mixed ligand chelates were found to have higher stabilities than would be predicted on statistical considerations. The enhancement of the complexation constant of the mixed ligand chelates has been explained on statistical considerations and the possibility of simultaneous π-bonding between Cd(II) and both the ligands.

Studies on Mass Spectrometry of Metal Chelates. IV. Synthesis and Mass Spectrometry of Cobalt(III) Mixed Ligand Chelates

Abstract The ligand substitution reaction of Co(acac)3 proceeded with other ligands L (L=oxine, 2-Me-oxine, 4-Me-oxine, 5-Me-oxine, and 7-Me-oxine), to afford mixed ligand chelates, Co(acac)2(L) and Co(acac)(L)2. Their mass spectra gave the following fragmentation patterns. The Co(acac)2(L) type chelate gave a fragment ion Co(acac)(L), produced by the loss of one molecule of acac from the molecular ion. At the same time it produced another fragment ion, Co(acac)2, by the loss of L from the molecular ion. From this fragmentation pattern it was confirmed that the compound is a mixed ligand chelate having the binding ratio Co: acac: L=1: 2: 1. The Co(acac)(L)2 type chelate produced a fragment ion, Co(acac)(L), by the loss of one molecule of L from the molecular ion, and another fragment ion of Co(L)2 by the loss of acac from the molecular ion. From this fragmentation pattern it was confirmed that the compound is another mixed ligand chelate having the binding ratio Co: acac: L=1: 1: 2.

Interligand transmetallic charge-transfer transitions in mixed-ligand chelates

In chelates of divalent zinc which have two different aromatic ligands, a new absorption band is observed in the visible region. This new band is interpreted as arising from a π→π* interligand transmetallic charge-transfer (ITCT) transition. The nature of this type of charge-transfer transition in a chelate molecule, using a molecular orbital model, is examined. Experimental results for the chelates (3,4-toluenedithiolato)(1,10-phenanthroline)zinc(II), (3,4-toluenedithiolato)(2,2′-dipyridyl)zinc(II),and (3,4-toluenedithiolato)(2,2′-biquinoline)zinc(II) are presented.

Mixed ligand chelates of Cu(II) with some carboxylic and phenolic acids

The nature of the mixed complexes of Cu(II) with bidentate ligands such as carboxylic and phenolic acids, was studied in aqueous medium by carrying out potentiometric titrations of the metal ion with the various chelating agents. Evidence for the formation of 1:1 chelates of Cu(II) with different ligands such as succinic, phthalic, 5-sulfosalicylic acid, 3:5-dinitrosalicylic acid, adipic and 4-hydroxy salicylic acids was found. Cu(II) in the presence of equimolar concentrations of two ligands formed mixed ligand chelates containing 1:1:1 molar ratios of Cu(II) and the two ligands. The formation constants of the complexes were calculated. It was observed that, (i) log K 5 >log K 2 + log K 2 when both ligands are carboxylic acids and (ii) log K 5 < Log K 1 + log K 2 when both the ligands are phenolic acids or when one ligand is a phenolic and the other a carboxylic acid.

Mixed ligand amino acid chelates of copper(II) and nickel(II) aspartates

Potentiometric studies are described for the formation of the mixed ligand chelates of Cu(II) and Ni(II) with aspartic acid as a primary ligand, and glycine, α-alanine, valine or leucine as secondary ligands. The formation constants for the mixed chelates are generally less than the K 2 values of corresponding simple chelates. Further, there is not much difference amongst their values within a series, the order of relative stability, however, being glycine > α-alanine > valine > leucine.

Mixed ligand chelates of uranyl ion

To study the nature of the mixed complexes of UO 2(II) ion with bidentate carboxylic and phenolic acids, potentiometric titrations of UO 2(II) ion with various bidentate chelating agents were carried out. Evidence for the formation of 1 : 1 chelates of UO 2(II) with different ligands such as phthalic, adipic, succinic, 3 : 5-dinitrosalicylic and 5-sulphosalicylic acids was found. A study of the UO 2(II) ion in the presence of equimolar concentrations of two ligands showed the formation of mixed ligand chelates containing 1 : 1 : 1 molar ratios of UO 2(II) and the two ligands. Formation constants of the mixed chelates are calculated and the chelates are shown to have formed in simultaneous equilibria. The lower values of stability constants of mixed ligand chelates than the sum of individual log stability constants of the first and second ligand are discussed.

Mixed ligand chelates of scandium(III) in aqueous solution

Mixed ligand chelates of the 1 : 1 scandium(III)-ethylene-diaminetetraacetic acid (EDTA) chelates with various secondary ligands have been investigated by a potentiometric method at 25·00°C and in 0·1 M KNO 3. Secondary ligands were disodium 1,2-dihydroxy-benzene-3,5-disulfonate(Tiron); sodium 2,3-dihydroxynaphthalene-6-sulfonate (DHN) and pyrocatechol (PY). Mixed ligand chelate formation has been found in all cases. 1:1:1 Sc(III)-EDTA- Secondary ligand chelates are more stable than the corresponding Y(III) chelates, but they are more susceptible to hydrolysis as a result the smaller ionic radius.

An electron spin resonance study of the copper(II) chelates of cyclobutane-1,1-dicarboxylic acid and their mixed ligand chelates

The X-band e.s.r. spectra of the copper(II) chelate of cyclobutane-1,1-dicarboxylic acid formed in dimethylformamide, dimethyl sulphoxide, or trimethyl phosphate show that dimeric species are formed which give rise to magnetic dipole–dipole coupling in dimethylformamide or dimethyl sulphoxide and predominantly exchange coupling when trimethyl phosphate is used as the solvent. The introduction of salicyclic, mandelic, benzilic, malic, or citric acid results in the formation of monomeric mixed ligand complexes though minor amounts of dimeric species are present. The ‘triplet’ state spectra have been used to extract structural and magnetic parameters of the copper(II) dimeric chelates.

The formation of mixed ligand complexes by metal chelates and some buffer components

A method for the determination of the stability constants of mixed ligand Complexes of metals is described. The influence of the buffer components ammonia (NH 3), imidazole (Im)and hexamethylenetetramine (U) on the murcury (II)-TTHA system was investigated. The binuclear mercury (II)-TTHA chelate has a strong tendancy to coordinate two additional ligands. The following stability constants of mixed ligand chelates were determined: ▪. Potentiometric titrations were performed to check the effects of the buffers on compleximetric titrations.

Multiple emission in mixed ligand metal chelates

Absorption and emission spectra, lifetimes and quantum yields are reported for mixed ligand chelates of 1,10-phenanthroline and 2,2'-dipyridyl of Rh(III). The mixed ligand complexes, [Rh(phen) 2(dip)]Cl 3 and [Rh(dip) 2(phen)]Cl 3, are found to possess more than one phosphorescence emission pathway. Each ring system is found to emit with a characteristic spectrum and lifetime. Energy transfer between ligands in the triplet state is noted and a rate constant for this process calculated. Quantum yield variations with excitation wavelength are rationalized. A localized exciton model is proposed for the multiple emission phenomena.

Mixed ligand rare earth chelates of EDTA with TPP and ATP

Stability constants of protonated 1:1 and normal 1:1 mixed ligand chelates of rare earths with EDTA and TPP and for the normal 1:1 mixed ligand chelates of rare earths with EDTA and ATP are investigated by a potentiometric method at 35°C and 0·10 ionic trength. The stabilities decrease in the order Tm(III) > Er(III) > Ho(III) > Dy(III) > Tb(III) > Y(III) > Gd(III) > Eu(III) > Sm(III) > Nd(III) > Pr(III) > Ce(III) > La(III) for both for protonated 1:1 and normal 1:1 mixed ligand chelates of TPP. For the normal chelates of ATP, the stabilities increase in the order La(III) < Ce(III) < Pr(III) < Nd(III) < Gd(III) < Sm(III) < Eu(III) < Y(III) < Tb(III) < Dy(III) < Ho(III) < Er(III) < Tm(III).

The chromatographic behaviour and nature of metal chelates of 1-(2-pyridylazo)-2-naphthol

The relationships between the thin-layer chromatographie behaviour of solutes, the solvent composition and the water content of silica gel were derived on the basis of the mass action law applied to Martin's equation. The relationships were proved experimentally by studying l-(2-pyridylazo)-2-naphthol, its isomers and its metal chelates with copper, nickel, cobalt and iron. The results suggest that an oxygen atom of the solutes is the centre of bonding to silica gel. Mixed ligand chelates of copper with PAN and diverse ligands were studied ; an increase of R F values was related to the affinity of the auxiliary ligand for the CuPAN + species. The extraction mechanism of the iron chelate with PAN appears to be complex and involves at least partial reduction to iron(II) in the chelate.

Determination of the orbital ground state symmetry of paramagnetic complexes by nuclear magnetic resonance

Analysis of the non-Curie temperature dependence of the ligand contact shifts in mixed ligand complexes of Cr(III) with 4,7-dimethyl- ortho-phenanthroline and 4,4′-dimethyl-α,α′-bipyridine has shown that one of the mixed ligand chelates, ML 2L′, possesses an A orbital ground state, while MLL 2′ possesses the B orbital ground state in C 2 symmetry. Depending on the assumed spin delocalization mechanism, a given ground state may be associated with a given mixed ligand chelate. Simple orbital energy considerations indicate that the different orbital ground states are to be expected for the pair of mixed ligand complexes. Some applications of this technique for obtaining information on metal-ligand bonding are discussed.

Thermometric titration studies of mixed ligand complexes of thorium

Mixed-ligand chelates consisting of two different multidentate ligands linked to a central thorium(IV) ion have been prepared in aqueous solution and their heats of formation studied thermo metrically. Pyrocatechol, tiron, chromotropic acid, potassium hydrogen phthalate, 8-hydroxyquinoline-S-sulphonic acid, iminodiacetic acid, 5-sulphosalicylic acid and salicylic acid were used as the secondary ligands, while ethylenediaminetetra-acetate and 1, 2-diaminocyclohexane- N,N,N',N'-tetra-acetate were used as primary ligands. Δ H values for the overall reactions are given, and where possible, the Δ H and Δ S values for the specific secondary ligand addition were calculated. The overall stability of the mixed-ligand chelates and the enhanced stability of EDTA mixed chelates relative to the analogous DCTA chelates were found to be due to entropy rather than enthalpy effects.

Structures of five- and six-coordinated mixed-ligand chelates of nickel(II) containing sulfur and nitrogen donor atoms

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStructures of five- and six-coordinated mixed-ligand chelates of nickel(II) containing sulfur and nitrogen donor atomsP. S. Shetty and Quintus FernandoCite this: J. Am. Chem. Soc. 1970, 92, 13, 3964–3969Publication Date (Print):July 1, 1970Publication History Published online1 May 2002Published inissue 1 July 1970https://doi.org/10.1021/ja00716a022RIGHTS & PERMISSIONSArticle Views207Altmetric-Citations74LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (666 KB) Get e-Alerts Get e-Alerts

Mixed ligand chelates of copper(II) with 8-quinolinol and arylhydroxycarboxylic acids: Part IV. Electronic absorption spectra of copper(II) chelates with 5-halogeno-8-quinolinols and arylhydroxycarboxylic acids

Mixed ligand chelates of copper(II) with 8-quinolinol and arylhydroxycarboxylic acids: Part IV. Electronic absorption spectra of copper(II) chelates with 5-halogeno-8-quinolinols and arylhydroxycarboxylic acids