Seven-coordinate complexes of iron(II) with pentadentate macrocyclic ligands

Drew, Michael G. B.; Othman, Abdul Hamid; Hill, W. E.; Mcilroy, P. D. A.; Nelson, S. M.

doi:10.1016/s0020-1693(00)89819-9

Cited by 15 publications

(4 citation statements)

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“…Access to a PBP shaped coordination sphere can be straightforward. Following a strategy documented in the 70s, [3][4][5] this geometry can be designed using a suitable pentadentate ligand (Fig. 1) to occupy five equatorial coordination sites of the metal center.…”

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confidence: 99%

Magnetic anisotropy of transition metal and lanthanide ions in pentagonal bipyramidal geometry

et al. 2022

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mentioning

confidence: 99%

Magnetic anisotropy of transition metal and lanthanide ions in pentagonal bipyramidal geometry

et al. 2022

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“…This ligand was chosen because of the proximity of the asymmetric centers to the metal ion. It was known to lead to a PBP coordination sphere for Mn II , and since a penta-aza ligand is also suitable to stabilize a PBP coordination sphere for Fe II , ,, L N5 R , R and L N5 S , S appeared adapted to our aim. The ligand was actually formed in a template reaction with FeCl 2 to give the respective PBP Fe II complex [FeL N5 R , R Cl(MeOH)]Cl·H 2 O ( 1 R ), or [FeL N5 S , S Cl(MeOH)]Cl·H 2 O ( 1 S ).…”

Section: Results and Discussionmentioning

confidence: 99%

Homochiral SCM Built of Tetrahedral and Pentagonal Bipyramidal Fe(II) Units Bridged by Chlorine

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Suaud

et al. 2023

Crystal Growth & Design

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Each enantiomer of a chiral pentagonal bipyramidal (PBP) FeII complex ([FeLN5R,R Cl(MeOH)]Cl·H2O, 1 R, or [FeLN5S,S Cl(MeOH)]Cl·H2O, 1 S) has been obtained using either the R or the S stereoisomer of the macrocyclic pentadentate ligand formed in a template-condensation reaction of the tetraamine N,N′-Bis-{(1R,2R)-[2-(amino)]cyclohexyl}-1,2-diaminoethane, or its (1S,2S) enantiomer, and 2,5-diacetylpyridine, respectively LN5R,R and LN5S,S . Subsequently, the 1-D coordination polymers [FeLN5R,R {FeCl4}], 2 R, and [FeLN5S,S {FeCl4}], 2 S, were formed by reacting respectively 1 R or 1 S with 1 equiv of FeCl2(H2O)4. These chain compounds consist of an alternation of PBP and tetrahedral FeII units sharing a Cl atom. Theoretical calculations reveal large magnetic anisotropy for each Fe center but of different type with axial zero-field splitting parameter D of respectively −30 cm–1 and 15 cm–1. The magnetic behavior for the 1-D compound revealed canted antiferromagnetic Fe–Fe interactions (J = −6 cm–1) and SCM behavior characterized by Δ/k B = 42 K with pre-exponential factor τ0 = 2.17 × 10–10 s. It was noted that this SCM behavior was accompanied by a magnetic order leading to a weak ferromagnet (i.e., canted antiferromagnet). The preparations, crystal structures (CCDC references 2214580–2214583), spectroscopic data, magnetic behaviors, and theoretical investigations are reported.

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“…1d). Two methods have been reported for synthesis of manganese complexes of pyridine-fused 15-membered macrocyclic pentamines: (1) Mn 2+ templated condensation of 2,6pyridinedicarboxaldehyde with triethylenetetramine to form the intermediate Schiff base macrocycle complex, 30 followed by reduction of the Schiff base moieties; 27 or, (2) synthesis of the metal-free macrocycle as described by Stetter 31 (aka the Richman-Atkins method 32,33 ), followed by complexation of the manganese salt. 21,26,28 The metal template method appears to work better for condensations of 2,6-diacetylpyridine, 16,[34][35][36] but it has been applied successfully to the corresponding dialdehyde by Dees et al in their synthesis of 1, 27 and by Malik et al in their synthesis of Schiff base MnI 2 complex 2 (Scheme 1).…”

Section: Chemistrymentioning

confidence: 99%

“…28 The results of our efforts to prepare the Schiff-base precursor (3, Scheme 1) to macrocyclic manganese complex 1 are shown in Scheme 1. We first attempted to condense pyridine-2,6-dicarboxaldehyde 38 with triethylenetetramine by heating with manganese(II) chloride in methanol or ethanol, as described by Drew et al, 30,35 but we were not able to crystallize the desired product (3) from the crude mixture. Switching the template salt to manganese(II) acetate and adding aqueous potassium iodide enabled the isolation of the corresponding MnI 2 complex 2 in good yield.…”

Section: Chemistrymentioning

confidence: 99%

Metal complexes of pyridine-fused macrocyclic polyamines targeting the chemokine receptor CXCR4

et al. 2015

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The chemokine receptor CXCR4 acts as a key cell surface receptor in HIV infections, multiple forms of cancer, and various other pathologies, such as rheumatoid arthritis and asthma. Macrocyclic polyamines and their metal complexes are known to exert anti-HIV activity, many acting as HIV entry inhibitors by specifically binding to CXCR4. Three series of pyridopentaazacylopentadecanes, in which the pyridine ring is fused to zero, one, or two saturated six-membered rings, were synthesized by manganese(ii)-templated Schiff-base cyclization of triethylenetetramine with various dicarbonyl compounds. By evaluating these macrocyclic polyamines and their complexes with Mn(2+), Cu(2+), Fe(3+), and Zn(2+), we have discovered novel CXCR4-binding compounds. The MnCl2 complex of a new pentaazacyclopentadecane with one fused carbocyclic ring (11) was found to have the greatest potency as an antagonist of the chemokine receptor CXCR4 (IC50: 0.014 μM), as evidenced by inhibiting binding of CXCL12 to PBMCs (peripheral blood mononuclear cells). Consequently, this compound inhibits replication of the CXCR4-using (X4) HIV-1 strain NL4-3 in the TZM-bl cell line with an IC50 value of 0.52 μM and low cytotoxicity (CC50: >100 μM). In addition, 18 other compounds were evaluated for their interaction with CXCR4 via their ability to interfere with ligand chemokine binding and HIV entry and infection. Of these, the metal complexes of the two more hydrophobic series with one or two fused carbocyclic rings exhibited the greatest potency. The Zn(2+) complex 21 was among the most potent, showing that redox activity of the metal center is not associated with CXCR4 antagonist activity.

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Seven-coordinate complexes of iron(II) with pentadentate macrocyclic ligands

Cited by 15 publications

References 2 publications

Magnetic anisotropy of transition metal and lanthanide ions in pentagonal bipyramidal geometry

Magnetic anisotropy of transition metal and lanthanide ions in pentagonal bipyramidal geometry

Homochiral SCM Built of Tetrahedral and Pentagonal Bipyramidal Fe(II) Units Bridged by Chlorine

Metal complexes of pyridine-fused macrocyclic polyamines targeting the chemokine receptor CXCR4

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