Bicyclam [6,6′-bi(1,4,8,11-tetra-azacyclotetradecane)]: a ditopic receptor for homo- and hetero-bimetallic complexes

Fabbrizzi, Luigi; Montagna, Laura; Poggi, Antonio; Kaden, Thomas A.; Siegfried, Liselotte

doi:10.1039/dt9870002631

Cited by 55 publications

(27 citation statements)

References 3 publications

(4 reference statements)

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“…This effect is described in literature. [9] The stability constant K equals 2.29 at room temperature. The equilibrium between square planar/ octahedral : 70% / 30%.…”

Section: Resultsmentioning

confidence: 99%

Determination of the number of unpaired electrons in metal-complexes. A comparison between the Evans’ method and susceptometer results

et al. 2005

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1,4,8,11-tetraazacyclotetradecane (cyclam) is widely known as an ideal ligand for chelating heavy metal ions such as Ni 2+ and Cu 2+ in aqueous media. In this work the consequences of chelation on the preference for high spin or low spin configuration were investigated for Fe 3+ , Ni 2+ , Cu 2+ and Cr 3+. Two methods were used to determine the number of unpaired electrons in the solid and dissolved complex. First the change of magnetic susceptibility of the crystalline powder as a function of temperature was measured. In the second case Evans NMR-based method was used to obtain information about the number of unpaired electrons in the dissolved complexes. In some cases, such as Fe 3+ and Ni 2+ , a discrepancy between the two methods was noticed. This behaviour is discussed in terms of the preference of the large high spin Ni 2+-ion to switch to the smaller low spin Ni 2+-ion in the aqueous environment, which better fits the cavity of the ligand in the square planar geometry. The results are influenced by the geometry of the complex, the aggregation state and the dimensions of the ions.

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“…This effect is described in literature. [9] The stability constant K equals 2.29 at room temperature. The equilibrium between square planar/ octahedral : 70% / 30%.…”

Section: Resultsmentioning

confidence: 99%

Determination of the number of unpaired electrons in metal-complexes. A comparison between the Evans’ method and susceptometer results

et al. 2005

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“…As expected, the Cu-N bond lengths (to NCH 2 Ph) of 2.0708(12) and 2.0719(12) Å are longer than the remaining Cu-N bond lengths (to NH) at 2.0207(13) and 2.0272(13) Å. The counter ions are weakly coordinated to the metal, with a 2.7325(16) Å Cu(1)-O(1) bond length and a Cu(1)-O(4) length of 2.5663 (14) Å. There is also a hydrogen bond interaction between the coordinated nitrate atom O(1) and the methanol O(7) (see CIF file).…”

Section: Crystal Structuresmentioning

confidence: 95%

Macrocyclic ligand design. Interaction of a series of successively N-benzylated derivatives of 1,4,8,11-tetraazacyclotetradecane (cyclam) with copper(ii) and nickel(ii)

et al. 2003

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The interaction of a series of N-benzylated cyclam ligand derivatives incorporating from one to four benzyl groups with nickel() and copper() is reported. The isolation of a selection of 1 : 1 (metal : ligand) complexes of both metals has been carried out and visible spectral, EPR, electrochemical and X-ray determinations have been employed to probe the nature of the respective complexes in both the solid state and in solution. Emphasis has been given to investigating the effect of the successive N-benzylation along this ligand series on the properties of the above complexes. The UV-VIS spectra obtained for each series of metal complexes indicate that the sequential introduction of N-benzyl substituents produces a change to lower ligand fields of the corresponding macrocyclic tetramines. Cyclic voltammograms of both the nickel() (low-spin) and copper() complexes both yield evidence for M()/M() as well as M()/M() couples in acetonitrile.

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“…6,6'-Bis (1,4,8,11-tetraazacyclotetradecane-5,7-dione) was initially prepared in similar manner to that described by Fabbrizzi et al [18] ,8.43;N,24.65. Found: C,52.98;H,8.11;N,24.76. This compound was then converted to 9 using the published procedure [18] ,11.63;N,27.80. Found: C,59.34;H,11.12;N,27.56.…”

Section: -(4-nitrobenzyl)-14811 Tetraazacyclotetradecane⋅025h 2mentioning

confidence: 99%

“…The synthesis of the double-ring macrocyclic ligand system 11, starting from the previously reported [17,18] bis-ring precursor 9, was carried out using the sequence shown in Scheme 3. Alkylation of 9 with 4-nitrobenzyl bromide yielded 10.…”

Section: Jan-feb 2005mentioning

confidence: 99%

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Synthesis of one-, two- and three-ring macrocyclic, bifunctional compounds for use in radiolabelling monoclonal antibodies

Rami

Dong

Lindoy

et al. 2005

Journal of Heterocyclic Chemistry

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Bicyclam [6,6′-bi(1,4,8,11-tetra-azacyclotetradecane)]: a ditopic receptor for homo- and hetero-bimetallic complexes

Abstract: Bicyclam [6,6'-bi( 1,4,8,11 -tetra-azacyclotetradecane)] ( L2) was prepared by reducing ~ ~~ ~ t Non-S.I. units employed: B.M. = 9.27 x J T-', cal = 4.184 J.

Cited by 55 publications

References 3 publications

Determination of the number of unpaired electrons in metal-complexes. A comparison between the Evans’ method and susceptometer results

Determination of the number of unpaired electrons in metal-complexes. A comparison between the Evans’ method and susceptometer results

Macrocyclic ligand design. Interaction of a series of successively N-benzylated derivatives of 1,4,8,11-tetraazacyclotetradecane (cyclam) with copper(ii) and nickel(ii)

Synthesis of one-, two- and three-ring macrocyclic, bifunctional compounds for use in radiolabelling monoclonal antibodies

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