A New Tris(phosphonomethyl) Monoacetic Acid Cyclam Derivative: Synthesis, Acid‐Base and Metal Complexation Studies

Lima, Luı́s M. P.; Delgado, Rita; Plutnar, Jan; Hermann, Petr; Kotek, Jan

doi:10.1002/ejic.201000919

Cited by 5 publications

(3 citation statements)

References 53 publications

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“…Importantly, it is also higher than the values reported for the complexes of H 4 dota ( pCu = 15.20) 28 and H 4 teta ( pCu = 14.20). 29 All the ligands presented in…”

Section: Thermodynamic Stability Of the Complexesmentioning

confidence: 99%

Improving the stability and inertness of Cu(ii) and Cu(i) complexes with methylthiazolyl ligands by tuning the macrocyclic structure

et al. 2016

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A tacn based ligand bearing two methylthiazolyl arms (no2th) was synthesized with the aim to find ligands forming very stable and inert complexes with Cu(ii) and Cu(i) in aqueous medium for radiopharmaceutical applications. The no2th ligand was efficiently prepared following the orthoamide intermediate synthesis. The complexes with Cu(2+) and Zn(2+) were obtained and analyzed by X-ray diffraction. The [Cu(no2th)](2+) complex presents a pentacoordinated distorted square pyramidal coordination geometry, while the metal ion in [Zn(no2th)](2+) adopts a hexacoordinated distorted trigonal prismatic geometry involving the coordination of a perchlorate counter ion. The acid-base properties of no2th have been studied using potentiometric titrations, and the stability constants of Cu(2+) and Zn(2+) complexes were determined by potentiometric and UV-vis titrations using H4edta as a competitor ligand. The stability constant determined for the Cu(2+) complex is rather high (log KCuL = 20.77 and pCu = 17.15), and moreover no2th exhibits a high selectivity for copper(ii) in relation to zinc(ii). The kinetics of the copper(ii) complexation process is very fast even in acidic medium. In addition, the [Cu(no2th)](2+) complex was found to be inert under rather harsh conditions (up to 2 M HCl and 60 °C), displaying a very high half-life time of about 15 days in 2 M HCl at 90 °C. The electrochemical reduction of the copper(ii) complex in water leads to the reversible formation of a stable copper(i) species. Spectroscopic studies performed by NMR, UV-vis and EPR, assisted by theoretical calculations, show that the [Cu(no2th)](2+) complex presents a structure in solution similar to that observed in the solid state. When compared to its cyclam di-N-methylthiazolyl counterpart, the results reported in this paper unambiguously show that replacing the cyclam unit by a tacn moiety improves the stability and inertness of its Cu(ii) and Cu(i) complexes.

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“…Importantly, it is also higher than the values reported for the complexes of H 4 dota ( pCu = 15.20) 28 and H 4 teta ( pCu = 14.20). 29 All the ligands presented in…”

Section: Thermodynamic Stability Of the Complexesmentioning

confidence: 99%

Improving the stability and inertness of Cu(ii) and Cu(i) complexes with methylthiazolyl ligands by tuning the macrocyclic structure

et al. 2016

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“…Some time ago, we started investigations of cyclam‐based ligands containing phosphorus acid pendant arms,25–36 which are suitable for complexation of the first‐row transition metal ions. Optimal properties are exhibited especially by ligands having six donor atoms (i.e., with two coordinating pendant arms).…”

Section: Introductionmentioning

confidence: 99%

Bifunctional Cyclam‐Based Ligands with Phosphorus Acid Pendant Moieties for Radiocopper Separation: Thermodynamic and Kinetic Studies

Paúrová

Havlíčková

Pospisilova

et al. 2015

Chemistry A European J

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Two macrocyclic ligands based on cyclam with trans-disposed N-methyl and N-(4-aminobenzyl) substituents as well as two methylphosphinic (H2L1) or methylphosphonic (H4L2) acid pendant arms were synthesised and investigated in solution. The ligands form stable complexes with transition metal ions. Both ligands show high thermodynamic selectivity for divalent copper over nickel(II) and zinc(II)-K(CuL) is larger than K(Ni/ZnL) by about seven orders of magnitude. Complexation is significantly faster for the phosphonate ligand H4L2, probably due to the stronger coordination ability of the more basic phosphonate groups, which efficiently bind the metal ion in an "out-of-cage" complex and thus accelerate its "in-cage" binding. The rate of Cu(II) complexation by the phosphinate ligand H2L1 is comparable to that of cyclam itself and its derivatives with non-coordinating substituents. Acid-assisted decomplexation of the copper(II) complexes is relatively fast (τ1/2 = 44 and 42 s in 1 M aq. HClO4 at 25 °C for H2L1 and H4L2, respectively). This combination of properties is convenient for selective copper removal/purification. Thus, the title ligands were employed in the preparation of ion-selective resins for radiocopper(II) separation. Glycidyl methacrylate copolymer beads were modified with the ligands through a diazotisation reaction. The separation ability of the modified polymers was tested with cold copper(II) and non-carrier-added (64)Cu in the presence of a large excess of both nickel(II) and zinc(II). The experiments exhibited high overall separation efficiency leading to 60-70% recovery of radiocopper with high selectivity over the other metal ions, which were originally present in 900-fold molar excess. The results showed that chelating resins with properly tuned selectivity of their complexing moieties can be employed for radiocopper separation.

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“…The trisphosphonate monoacetate cyclam ligand L 11 was synthesised and its complexation properties with transition metal and lanthanides investigated. 28 Potentiometric and NMR titrations were used to study the compounds and determine stability constants with the zinc(II) complex shown to have a predominant isomer with one phosphonate arm bound in addition to the cyclam ring N donors.…”

Section: Tetraaza Macrocycles: Cyclammentioning

confidence: 99%

Macrocyclic coordination chemistry

Archibald

2012

Annu. Rep. Prog. Chem., Sect. A: Inorg. Chem.

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This chapter reviews the literature published on macrocyclic coordination chemistry during 2011. The aim is to describe the key advances, focusing predominantly on complexes formed with transition metal and lanthanide ions. Porphyrin ligands and supramolecular chemistry are not covered. Trends in the development of macrocyclic chelator design and the impact of the coordination chemistry of the chelators on both existing and emerging applications are discussed. HighlightsThere were some interesting and important advances in this field reported in 2011. The progressing development of the immobilisation of macrocycles on surfaces and as components of supramolecular species are particularly important with catalytic complexes on nanoparticles participating in highly effective oxidation reactions 1 and also the formation of constructs for multi-modal imaging in vivo. 2,3 Similarly the incorporation of functionalised macrocyclic complexes into micelles and vesicles facilitated enhanced DNA cleavage properties. 4 MRI imaging is the source of the greatest number of publications in this area but often the same types of chelators and techniques are employed. Deviations from the normal approach include continued efforts to design macrocyclic complexes for PARACEST MR imaging; this can be carried out by optimising slow water exchange with appropriate donor choice, or incorporating the functional macrocyclic component into micelles for sensing, and has resulted in key advances in 2011. [5][6][7] Another imaging paper reports optimised methods for efficient dynamic nuclear polarisation of 89 Y which could ultimately lead to clinical use of targeted complexes in MR imaging with the significant signal enhancement offered by this technique.

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A New Tris(phosphonomethyl) Monoacetic Acid Cyclam Derivative: Synthesis, Acid‐Base and Metal Complexation Studies

Abstract: A new cyclam-based ligand, [4,8,11-tris(phosphonomethyl)-1,4,8,11-tetraazacyclotetradec-1-yl]

Cited by 5 publications

References 53 publications

Improving the stability and inertness of Cu(ii) and Cu(i) complexes with methylthiazolyl ligands by tuning the macrocyclic structure

Improving the stability and inertness of Cu(ii) and Cu(i) complexes with methylthiazolyl ligands by tuning the macrocyclic structure

Bifunctional Cyclam‐Based Ligands with Phosphorus Acid Pendant Moieties for Radiocopper Separation: Thermodynamic and Kinetic Studies

Macrocyclic coordination chemistry

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