Syntheses and crystal structures of gadolinium and europium complexes of AAZTA analogues

Sengar, Raghvendra S.; Nigam, Archana; Geib, Steven J.; Wiener, Erik C.

doi:10.1016/j.poly.2009.03.005

Cited by 16 publications

(11 citation statements)

References 18 publications

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“…The calculated distances between the Eu 3+ ion and the amine nitrogen atoms of the ligand (2.66-2.83 Å) are only slightly longer than those observed in the solid state for the Gd 3+ complex of AAZTA (2.60-2.78 Å), while following the sequence Ln-N1 < Ln-N3 < Ln-N2 (see Figure 5 for atom numbering). 32 The N3-CH 2 -CH 2 -N dihedral angle (-33.2°) is close to those observed in the Eu 3+ complex of the related AAZTA-CH 2 CH 2 OH ligand (-28.2°), 33 the Ga 3+ complexes with hexadentate ligands based on the AMPED platform 34 and the Cu complex with AAZTA, resulting in twist-chair conformations of the 1,4-diazepine seven-membered ring. This torsion angle is somewhat smaller in the Gd 3+ complex of AAZTA-C 2 H 4 COOBn (-20.8°) 35 and Cu(H 2 AAZTA) (-23.7°), 36 approaching an eclipsed conformation in the Gd 3+ complex of AAZTA (-2.9°), 32 which is characteristic of the chair conformation.…”

Section: Resultssupporting

confidence: 62%

AMPED: a new platform for picolinate based luminescent lanthanide chelates

et al. 2015

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The synthesis of a new nonacoordinating ligand based on an AMPED (6-amino-6-methylperhydro-1,4-diazepine) scaffold functionalized by three picolinate (6-carboxy-2-methylpyridine) arms is described. Coordination of lanthanide cations (Ln = Eu and Tb) was investigated by spectrophotometric titrations monitored by UV-Vis absorption and steady-state emission spectroscopy, showing the formation of [LnL] complexes in aqueous solutions. The corresponding Eu and Tb complexes were isolated and characterized, and their spectroscopic properties (luminescence quantum yields, excited state lifetimes) were determined in buffered water (TRIS/HCl, pH 7.4) and compared to the data reported in the literature for related systems. DFT modelling of the complexes showed the picolinate arms to be perfectly wrapped around the Ln(3+) cations, affording an excellent shielding of the metal as confirmed by the determination of the hydration number of q = 0 for both complexes. The high resolution emission spectrum was used to determine the radiative lifetime of Eu in the complex (τrad = 3.05 ms) and the metal-centred luminescence quantum yield (0.20). The modest 0.10 overall luminescence quantum yield of the Eu complex is a consequence of an energy transfer with medium efficiency (0.50) and a low metal centred luminescence efficiency attributed in part to the presence of numerous NH and CH bonds in close proximity to the metal centre.

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Section: Resultssupporting

confidence: 62%

AMPED: a new platform for picolinate based luminescent lanthanide chelates

et al. 2015

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“…Compound (I) was synthesized according to the literature procedure of Sengar et al (2009). Colorless crystals suitable for X-ray analysis were obtained by slow evaporation from a dichloromethane solution of (I) in air.…”

Section: Methodsmentioning

confidence: 99%

“…Recently, we reported the syntheses and characterization of new bifunctional AAZTA ligands with hydroxy side chains, and the crystal structures of their gadolinium and europium complexes (Sengar et al, 2008(Sengar et al, , 2009. The title compound, (I), was used as a precursor for one of the bifunctional ligands with a hydroxy arm and the complete synthesis and spectroscopic characterization of (I) was provided (Sengar et al, 2009). We report herein the molecular structure of compound (I) determined by X-ray crystallography (Fig.…”

Section: Commentmentioning

confidence: 99%

Tri-tert-butyl 3-oxo-4-oxa-1,8,11-triazaspiro[5.6]dodecane-1,8,11-triacetate

et al. 2010

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“…Hence, several methyl-modified analogues were designed for their further bioconjugation. Hydroxymethyl AAZTA derivative (AAZTA-MeOH) was described by Sengar et al and was synthesized following a procedure similar to the original reaction sequence (Scheme 5), nitroethane being replaced with 2-nitroethanol [39]. However, the last deprotection step with trifluoroacetic acid (TFA) led to the formation of a lactone after cyclization between the hydroxyl group with one of the two tert-butyl esters located on the exocyclic nitrogen.…”

Section: Aazta Modulations To Obtain Bifunctional Chelating Agents (Bca)mentioning

confidence: 99%

AAZTA-Derived Chelators for the Design of Innovative Radiopharmaceuticals with Theranostic Applications

et al. 2022

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With the development of 68Ga and 177Lu radiochemistry, theranostic approaches in modern nuclear medicine enabling patient-centered personalized medicine applications have been growing in the last decade. In conjunction with the search for new relevant molecular targets, the design of innovative chelating agents to easily form stable complexes with various radiometals for theranostic applications has gained evident momentum. Initially conceived for magnetic resonance imaging applications, the chelating agent AAZTA features a mesocyclic seven-membered diazepane ring, conferring some of the properties of both acyclic and macrocyclic chelating agents. Described in the early 2000s, AAZTA and its derivatives exhibited interesting properties once complexed with metals and radiometals, combining a fast kinetic of formation with a slow kinetic of dissociation. Importantly, the extremely short coordination reaction times allowed by AAZTA derivatives were particularly suitable for short half-life radioelements (i.e., 68Ga). In view of these particular characteristics, the scope of this review is to provide a survey on the design, synthesis, and applications in the nuclear medicine/radiopharmacy field of AAZTA-derived chelators.

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Syntheses and crystal structures of gadolinium and europium complexes of AAZTA analogues

Cited by 16 publications

References 18 publications

AMPED: a new platform for picolinate based luminescent lanthanide chelates

AMPED: a new platform for picolinate based luminescent lanthanide chelates

Tri-tert-butyl 3-oxo-4-oxa-1,8,11-triazaspiro[5.6]dodecane-1,8,11-triacetate

AAZTA-Derived Chelators for the Design of Innovative Radiopharmaceuticals with Theranostic Applications

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