Toward novel sulphur-containing derivatives of tetraazacyclododecane: synthesis, acid–base properties, spectroscopic characterization, DFT calculations, and cadmium(<scp>ii</scp>) complex formation in aqueous solution

Tosato, Marianna; Verona, Marco; Doro, Riccardo; Tiezza, Marco Dalla; Orian, Laura; Andrighetto, A.; Pastore, Paolo; Marzaro, Giovanni; Marco, Valerio Di

doi:10.1039/d0nj00310g

Cited by 13 publications

(96 citation statements)

References 57 publications

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“…This was due to the very high complex stability which caused the complexation to start at very low pH (<2). An analogous result was observed for the Cd 2+ complexes 37 and it was attributed to the absence of competitive protonation equilibria on SCH 3 , allowing this functional group to strongly bind to metal ions also at very acidic pH. The determined equilibrium constants are summarized in Table 1 .…”

Section: Resultssupporting

confidence: 68%

“…DO4S, DO3S, DO3SAm, DO2A2S, and (2S,5S,8S,11S)-2,5,8,11-tetramethyl-1,4,7,10-tetraazacyclododecane (M4-cyclen) were synthesized according to previously reported procedures. 37 , 40 …”

Section: Methodsmentioning

confidence: 99%

“…The potentiometric, UV–vis, and NMR measurements were carried out as reported in detail previously. 37 Here a brief description is reported.…”

Section: Methodsmentioning

confidence: 99%

“… 2 , 36 However, these ligands are not predicted to be the chelators of election for Ag + since its soft character would prevent the formation of stable coordination bonds with hard donor groups like the carboxylates of DOTA and similar analogues. Our research group has recently introduced a series of novel macrocyclic chelators based on the 1,4,7,10-tetraazacyclododecane scaffold (cyclen) with sulfide side arms, 37 which were able to form very stable complexes with Cd 2+ . A similar affinity is expected with other soft metal ions including Ag + .…”

Section: Introductionmentioning

confidence: 99%

“…The above listed ligands have been considered also in our previous work. 37 In this work, a novel additional derivative was considered, (2S,5S,8S,11S)-2,5,8,11-tetramethyl-1,4,7,10-tetrakis(2-(methylsulfanyl)ethyl)-1,4,7,10-tetraazacyclododecane (DO4S4Me). It was designed to enforce the preorganization and enhance the rigidity of the donor atoms by introducing chiral methyl groups on the polyamine backbone.…”

Section: Introductionmentioning

confidence: 99%

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Highly Stable Silver(I) Complexes with Cyclen-Based Ligands Bearing Sulfide Arms: A Step Toward Silver-111 Labeled Radiopharmaceuticals

et al. 2020

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With a half-life of 7.45 days, silver-111 (β max 1.04 MeV, E γ 245.4 keV [ I γ 1.24%], E γ 342.1 keV [ I γ 6.7%]) is a promising candidate for targeted cancer therapy with β – emitters as well as for associated SPECT imaging. For its clinical use, the development of suitable ligands that form sufficiently stable Ag + -complexes in vivo is required. In this work, the following sulfur-containing derivatives of tetraazacyclododecane (cyclen) have been considered as potential chelators for silver-111: 1,4,7,10-tetrakis(2-(methylsulfanyl)ethyl)-1,4,7,10-tetraazacyclododecane (DO4S), (2S,5S,8S,11S)-2,5,8,11-tetramethyl-1,4,7,10-tetrakis(2-(methylsulfanyl)ethyl)-1,4,7,10-tetraazacyclododecane (DO4S4Me), 1,4,7-tris(2-(methylsulfanyl)ethyl)-1,4,7,10-tetraazacyclododecane (DO3S), 1,4,7-tris(2-(methylsulfanyl)ethyl)-10-acetamido-1,4,7,10-tetraazacyclododecane (DO3SAm), and 1,7-bis(2-(methylsulfanyl)ethyl)-4,10,diacetic acid-1,4,7,10-tetraazacyclododecane (DO2A2S). Natural Ag + was used in pH/Ag-potentiometric and UV–vis spectrophotometric studies to determine the metal speciation existing in aqueous NaNO 3 0.15 M at 25 °C and the equilibrium constants of the complexes, whereas NMR and DFT calculations gave structural insights. Overall results indicated that sulfide pendant arms coordinate Ag + allowing the formation of very stable complexes, both at acidic and physiological pH. Furthermore, radiolabeling, stability in saline phosphate buffer, and metal-competition experiments using the two ligands forming the strongest complexes, DO4S and DO4S4Me, were carried out with [ 111 Ag]Ag + and promising results were obtained.

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Section: Resultssupporting

confidence: 68%

“…DO4S, DO3S, DO3SAm, DO2A2S, and (2S,5S,8S,11S)-2,5,8,11-tetramethyl-1,4,7,10-tetraazacyclododecane (M4-cyclen) were synthesized according to previously reported procedures. 37 , 40 …”

Section: Methodsmentioning

confidence: 99%

“…The potentiometric, UV–vis, and NMR measurements were carried out as reported in detail previously. 37 Here a brief description is reported.…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Highly Stable Silver(I) Complexes with Cyclen-Based Ligands Bearing Sulfide Arms: A Step Toward Silver-111 Labeled Radiopharmaceuticals

et al. 2020

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Advances in macrocyclic chelators for positron emission tomography imaging

Wang²,

Kong

et al. 2023

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In recent years, radiometals have been successfully applied to medicine because of their breadth of decay properties and increased production and availability. Bifunctional chelators play a key role in radiometal‐based radiopharmaceuticals, affecting the labeling, targeting, and pharmacokinetics of bioconjugations and ensuring the stable complexation of the metal in vivo. The capacity of macrocycles to form complexes with extremely high thermodynamics, kinetics, and stability compared to acyclic chelators continues to pique the curiosity of pharmacists and biochemists among all prospective chelators utilized for the radiometal chelation. As new imaging modalities and therapeutic targets develop, the discovery of novel ligand structures with suitable chemical and biological features encourages the modification of chelators with charge and chemical properties. Herein, we present a comprehensive review of developments of macrocyclic chelators for PET radiopharmaceuticals, including innovative chelating agents with new structures and known chelating agent modifications, and their physical‐chemical properties, as well as their biological characteristics and applications in vivo.

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Ten-Membered Rings or Lager With One or More Nitrogen Atoms

Hermann

Kotek

Kubíček

2022

Comprehensive Heterocyclic Chemistry IV

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Toward novel sulphur-containing derivatives of tetraazacyclododecane: synthesis, acid–base properties, spectroscopic characterization, DFT calculations, and cadmium(ii) complex formation in aqueous solution

Abstract: New sulphur derivatives of cyclen, with potential complementary properties with respect to known compounds, have been synthesized and studied.

Cited by 13 publications

References 57 publications

Highly Stable Silver(I) Complexes with Cyclen-Based Ligands Bearing Sulfide Arms: A Step Toward Silver-111 Labeled Radiopharmaceuticals

Highly Stable Silver(I) Complexes with Cyclen-Based Ligands Bearing Sulfide Arms: A Step Toward Silver-111 Labeled Radiopharmaceuticals

Advances in macrocyclic chelators for positron emission tomography imaging

Ten-Membered Rings or Lager With One or More Nitrogen Atoms

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