Binuclear Lanthanide Research Articles

Synthesis and Magnetism of μ-phthalato Binuclear Lanthanide(III) Complexes (Ln = Dy and Nd)

Four novel binuclear Ln(III) complexes containing the dianion of phthalic acid (phth) as a bridging ligand have been synthesized, namely [Ln2(phth)(phen)4](CIO4)4.xH2O and [Ln2(phth)(NO2-phen)4](CIO4)4.xH2O (Ln = Dy, Nd; phth = dianion of phthalic acid; phen = 1,10-phenanthroline; NO2-phen = 5-nitro-1,10-phenanthroline). The complexes have been characterized by elemental analyses, IR, electronic spectra and conductances. The variable-temperature magnetic susceptibility (4-300K) of the complex [Dy2(phth)(NO5-phen)4](CIO4)4.6H2O has been determined, and the data were fit to the susceptibility equation derived from the spin Hamilton, Ĥ=δḼz 2+gβH·Ĵi+2Z′J′+MJ(Ĵz), by the least square method. The exchange interaction parameters are Z′J′ = -5. 94 × 10−4 cm−1 indicating that there is a weak antiferromagnetic spin exchange interaction between the lanthanide ions in the complex.

Binuclear lanthanide complexes as catalysts for the hydrolysis of double-stranded DNA

The efficient cleavage of plasmid DNA (pCAT) by binuclear lanthanide complexes was investigated. At 37°C and neutral pH, both Ho 2 3+L and Er 2 3+L promoted 100% conversion of supercoiled plasmid to the nicked circular form and linear form in 1 h. The corresponding saturation kinetics curve of cleavage of pCAT plasmid by binuclear lanthanide complexes showed the expected increase with catalyst concentration.

Synthesis and Magnetism of Binuclear Gd(III), Dy(III) and Nd(III) Complexes with Bromanilate Dianion as Bridging Ligand

Three new binuclear lanthanide(III) complexes, Ln2(phen)4(BA)(ClO4)4·nH2O (Ln = Nd and Dy, n = 3; Ln = Gd, n = 1; phen = 1,10-phenanthroline; BA2- = bromanilate dianion), have been synthesized and characterized. The variable-temperature magnetic susceptibilities of Gd2(phen)4(BA)(ClO4)4·H2O were measured over the temperature range 4–300 K. The observed susceptibility data were best-fit to those from the theoretical magnetic equation by a least-squares method, giving the following parameters: J = -0.10 cm−1, g = 1.95, R = 7.9×10−3.

Binuclear Lanthanide Complexes as Catalysts for the Hydrolysis of Bis(p‐nitrophenyl)‐phosphate and Double‐Stranded DNA

Binuclear Lanthanide Complexes as Catalysts for the Hydrolysis of Bis(<i>p</i>‐nitrophenyl)‐phosphate and Double‐Stranded DNA

Synthesis and magnetism of μ-phthalato binuclear lanthanide(III) complexes (Ln = Gd, Tb, Ho, Er)

Four novel binuclear Ln(III) complexes containing the dianion of phthalic acid(phth) as a bridging ligand have been synthesized, namely [(Ln 2(phth)(phen) 4] (ClO 4) 4·xH 2O (Ln = Gd, Tb, Ho, Er; Phen = 1,10-phenanthroline; phth = dianion of phthalic acid). The complexes have been characterized by elemental analyses, IR, electronic spectra, ESR and conductances. The variable-temperature magnetic susceptibility (4–300 K) of complex Gd 2[(phth)(phen) 4](ClO 4) 4 has been determined. A satisfactory fit to the theoretical curve derived from the spin Hamiltonian operator, Ĥ = − 2JŜ 1 · Ŝ 2 was obtained by the least squares method. The exchange interaction parameters are J = −0.25 cm −1 indicating the existence of a weak antiferromagnetic spin exchange interaction between the lanthanide ions in the complex.

Exchange interactions in lanthanide binuclear compounds. The cubic isotropic case

Following the idea of Lines a combined model for the description of exchange interactions in binuclear lanthanide compounds is proposed. Susceptibility expressions for lanthanide centres with an odd number of f electrons are developed assuming cubic ligand fields and isotropic exchange interactions. The latter are taken into consideration as a molecular field in the excited single-ion levels, but treated with greater accuracy using the Heisenberg model within the single-ion ground states. Model calculations on the basis of an antiferromagnetic coupling within the dimers show that temperatures where magnetic susceptibilities reach their maximum, T (χmax), vary widely when total spin S of the lanthanide is altered. The highest T (χmax) should be expected in the case of Gd 3+ (4f 7), Sm 3+ (4f 5) and Dy 3+ (4f 9). This is confirmed by experimental results so far obtained regarding binuclear complexes [Ln(C 5H 5) 2Br] 2 (Ln = Gd, Dy, Er and Yb).

Analysis of xylene mixtures using binuclear lanthanide(III) silver(I) NMR shift reagents

An alternative to IR spectroscopy for the quantification of xylene mixtures employing NMR spectroscopy and involving the use of binuclear lanthanide(III)-silver(I) NMR shift reagents.

15N, 1H and 13C NMR. A study of the complexation of binuclear lanthanide(III)‐silver(I) shift or relaxation reagents with substrates containing multiply bonded nitrogen

AbstractBinuclear lanthanide(III)‐silver(I) β‐diketonate chelates are effective NMR shift and relaxation reagents for substrates containing one or two multiply bonded nitrogen atoms, despite the fact that some of the substrates are able to react with lanthanide chelates alone. The silver cation is bonded to the nitrogen—nitrogen or nitrogen—carbon multiple bond. The lanthanide(III) chelate tetrakis anion is held in proximity to the substrate, without delocalization of spin density from the lanthanide to the studied nuclei (15N, 13C, 1H) of the substrate. Greater spectral simplification is achieved with a binuclear shift reagent than with a single lanthanide chelate in two ways. First, the complexation ability of the π electron pair may be greater than that of the heteroatom lone pair when that of the latter is lowered owing to steric (azobenzene, trans‐aldimine derivatives) or conjugative effects (benzonitrile is similar in this respect to heteroaryl substrates in which the heteroatom is devoid of basicity). Second, resolution may be far better preserved in cases where very strong binding to the lanthanide chelates results in extensive broadening of the NMR signals (imidazole, thiazole and oxazole derivatives).

A better solvent for binuclear lanthanide(III)-silver(I) NMR shift reagent studies

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA better solvent for binuclear lanthanide(III)-silver(I) NMR shift reagent studiesThomas J. WenzelCite this: J. Org. Chem. 1984, 49, 10, 1834–1835Publication Date (Print):May 1, 1984Publication History Published online1 May 2002Published inissue 1 May 1984https://doi.org/10.1021/jo00184a035RIGHTS & PERMISSIONSArticle Views157Altmetric-Citations11LEARN 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 (291 KB) Get e-Alerts Get e-Alerts

1H and 13C NMR studies of binuclear lanthanide(III):—silver(I) shift or relaxation reagents: Competition between several bonding sites in olefinic, aromatic and heteroaromatic compounds

AbstractThe relative abilities of weak Lewis bases to complex binuclear lanthanide(III)—silver(I) reagents were checked by inter‐ or intra‐ molecular competitions. Preferential complexation at one particular site was shown to be determined mainly by the occurrence of well localized π electrons, by the relief of strain effects or by the lack of steric hindrance. In benzofuran and methoxybenzene derivatives oxygen never interacts directly with the silver reagent and plays a role mainly through electronic effects. Unlike oxygen, sulphur in benzo[b]thiophene is the preferred site of complexation with the silver reagent. On complexation with binuclear shift reagents (lanthanide = Eu, Pr, Yb) the 1H NMR shifts were shown to result from several mechanisms. Better insight into the precise location of the reagent is obtained in 13C NMR by the use of the binuclear relaxation reagent Ag(tfa)‐Gd(fod)3.

Binuclear shift reagents for nuclear magnetic resonance spectrometry of aromatic and polycyclic aromatic compounds

The effects of adding binuclear lanthanide(III)-silver(I) shift reagents to aromatic compounds and phosphines are discussed. With aromatic compounds, the silver bonds at sites away from alkyl substituents so that selective shifts, leading to significant spectral clarification, are observed. Because of different shifts, the analysis of complex mixtures such as the methylbenzenes in gasoline can be performed in the presence of these shift reagents. A study of the relative shifting ability of the binuclear complexes formed with the ligand 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedione (fod), vs. 2,2,6,6-tetramethyl-3,5-heptanedione (thd), revealed that the fluorinated ligands are much more effective shift reagents.

New binuclear lanthanide NMR shift reagents effective for aromatic compounds

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNew binuclear lanthanide NMR shift reagents effective for aromatic compoundsT. J. Wenzel, T. C. Bettes, J. E. Sadlowski, and R. E. SieversCite this: J. Am. Chem. Soc. 1980, 102, 18, 5903–5904Publication Date (Print):August 1, 1980Publication History Published online1 May 2002Published inissue 1 August 1980https://doi.org/10.1021/ja00538a032RIGHTS & PERMISSIONSArticle Views385Altmetric-Citations58LEARN 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 (255 KB) Get e-Alerts Get e-Alerts