Synthesis and structural characterization of lanthanide(III) texaphyrins

Sessler, Jonathan L.; Mody, Tarak D.; Hemmi, Gregory; Lynch, Vincent M.

doi:10.1021/ic00066a032

Cited by 148 publications

(140 citation statements)

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“…This instability stands in contrast to what is true for most meso-free sp 3 -texaphyrins, which are generally quite stable and which can be separated by column chromatography over various supports with nearly quantitative recovery. 18,19 A possible explanation for the instability of 8 is that the two meso-aryl groups introduce strain that make the imine bonds more susceptible to solvolysis. While not an exact analogy, it is noteworthy that several meso-aryl substituted porphyrins have been reported that have distorted non-planar conformations.…”

Section: Synthesismentioning

confidence: 99%

New polyethyleneglycol-functionalized texaphyrins: synthesis and in vitro biological studies

et al. 2006

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The synthesis of four new analogues of motexafin gadolinium (MGd), a gadolinium(III) texaphyrin complex in clinical trials for its anticancer properties, is described. These new derivatives contain either 1,2-diaminobenzene or 2,3-diaminonaphthalene subunits as the source of the imine nitrogens and bear multiple 2-[2-(2-methoxyethoxy)ethoxy]ethoxy (PEG) groups, on either meso aryl or beta-pyrrolic substituents, to increase their water solubility. All four analogues were found to be more active in vitro than the parent system MGd as judged from cell proliferation assays using the PC3 and A549 cell lines.

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Section: Synthesismentioning

confidence: 99%

New polyethyleneglycol-functionalized texaphyrins: synthesis and in vitro biological studies

et al. 2006

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“…[16] Over the last few years, however, a small number of very promising q = 2 gadolinium complexes have been reported. [17][18][19] The introduction of three additional carboxylate groups on the heptadentate do3a 3À ligand suppresses anionic binding to the gadolinium centre by electrostatic repulsion.…”

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confidence: 99%

Structure, Stability, Dynamics, High‐Field Relaxivity and Ternary‐Complex Formation of a New Tris(aquo) Gadolinium Complex

Nonat

Fries

Pécaut

et al. 2007

Chemistry A European J

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The tripodal hexadentate picolinate ligand dpaa3- (H3dpaa=N,N'-bis[(6-carboxypyridin-2-yl)methyl]glycine) has been synthesised. It can form 1:1 and 1:2 lanthanide/ligand complexes. The crystal structure of the bis(aquo) lutetium complex [Lu(dpaa)(H2O)2] has been determined by X-ray diffraction studies. The number of water molecules was determined by luminescence lifetime studies of the terbium and europium complexes. The tris(aquo) terbium complex shows a fairly high luminescence quantum yield (22 %). The [Gd(dpaa)(H2O)3] complex displays a high water solubility and an increased stability (pGd=12.3) with respect to the analogous bis(aquo) complex [Gd(tpaa)(H2O)2] (pGd=11.2). Potentiometric and relaxometric studies show the formation of a soluble GdIII hydroxo complex at high pH values. A unique aquohydroxo gadolinium complex has been isolated and its crystal structure determined. This complex crystallises as a 1D polymeric chain consisting of square-shaped tetrameric units. In heavy water, the [Gd(dpaa)-(D2O)3] complex shows a quite high HOD proton relaxivity at high field (11.93 s(-1) mM(-1) at 200 MHz and 298 K) because of the three inner-sphere water molecules. The formation of ternary complexes with physiological anions has been monitored by relaxometric studies, which indicate that even under conditions favourable to the formation of adducts with oxyanions, the mean relaxivity remains higher than those of most of the currently used commercial contrast agents except for the citrate. However, the measured relaxivity (r1=7.9 s(-1) mM(-1)) in a solution containing equimolar concentrations of [Gd(dpaa)(D2O)3] and citrate is still high. The interaction with albumin has been investigated by relaxometric and luminescence studies. Finally, a new versatile method to unravel the geometric and dynamic molecular factors that explain the high-field relaxivities has been developed. This approach uses a small, uncharged non-coordinating probe solute, the outer-sphere relaxivity of which mimics that of the water proton. Only a routine NMR spectrometer and simple mathematical analysis are required.

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“…Monitoring the selective accumulation of gadolinium(III) texaphyrin in neoplasms by MRI enables the possibility of treatment planning and subsequent monitoring of the response I 2 of cancers to the radiation therapy. Gadolinium(III) texaphyrin is representative of a new class of compounds known as the texaphyrins (e.g., structures 1 and 2) (25)(26)(27).…”

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confidence: 99%

“…Texaphyrins are large planar porphyrin-like macrocycles that are capable of coordinating a range of relatively large cations, including Gd(III) and other members of the trivalent lanthanide series (26,27). In general, the complexes formed are stable and of a 1:1 metal-to-ligand stoichiometry (27 25 ,us after the pulse.…”

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confidence: 99%

Gadolinium(III) texaphyrin: a tumor selective radiation sensitizer that is detectable by MRI.

Young

Fan

Harriman

et al. 1996

Proc. Natl. Acad. Sci. U.S.A.

194

125

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Gadolinium(III) texaphyrin (Gd-tex2+) is representative of a new class of radiation sensitizers detectable by magnetic resonance imaging (MRI). This porphyrin-like complex has a high electron affinity [E1/2 (red.) approximately = -0.08 V versus normal hydrogen electrode] and forms a long-lived pi-radical cation upon exposure to hydrated electrons, reducing ketyl radicals, or superoxide ions. Consistent with these chemical findings, Gd-tex2+ was found to be an efficient radiation sensitizer in studies carried out with HT29 cells in in vitro as well as in in vivo single and multifraction irradiation studies with a murine mammary carcinoma model. Selective localization of Gd-tex2+ in tumors was confirmed by MRI scanning.

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Synthesis and structural characterization of lanthanide(III) texaphyrins

Cited by 148 publications

References 0 publications

New polyethyleneglycol-functionalized texaphyrins: synthesis and in vitro biological studies

New polyethyleneglycol-functionalized texaphyrins: synthesis and in vitro biological studies

Structure, Stability, Dynamics, High‐Field Relaxivity and Ternary‐Complex Formation of a New Tris(aquo) Gadolinium Complex

Gadolinium(III) texaphyrin: a tumor selective radiation sensitizer that is detectable by MRI.

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