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Petr Hermann - One of the best experts on this subject based on the ideXlab platform.
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The Influence of the Combination of Carboxylate and Phosphinate Pendant Arms in 1,4,7-Triazacyclononane-Based Chelators on Their 68Ga Labelling Properties
MDPI AG, 2015Co-Authors: Gábor Máté, Jakub Simecek, Johannes Notni, Miroslav Pniok, István Kertész, Hans-jürgen Wester, László Galuska, Petr HermannAbstract:In order to compare the coordination properties of 1,4,7-triazacyclononane (tacn) derivatives bearing varying numbers of Phosphinic/carboxylic Acid pendant groups towards 68Ga, 1,4,7-triazacyclononane-7-acetic-1,4-bis(methylenePhosphinic) Acid (NOPA) and 1,4,7- triazacyclononane-4,7-diacetic-1-[methylene(2-carboxyethyl)Phosphinic] Acid (NO2AP) were synthesized using Mannich reactions with trivalent or pentavalent forms of H-Phosphinic Acids as phosphorus components. Stepwise protonation constants logK1–3 12.06, 3.90 and 1.95, and stability constants with GaIII and CuII, logKGaL 24.01 and logKCuL 16.66, were potentiometrically determined for NOPA. Both ligands were labelled with 68Ga and compared with NOTA (tacn-N,N′,N″-triacetic Acid) and NOPO, a TRAP-type [tacn-N,N′,N″- tris(methylenePhosphinic Acid)] chelator. At pH 3, NOPO and NOPA showed higher labelling efficiency (binding with lower ligand excess) at both room temperature and 95 °C, compared to NO2AP and NOTA. Labelling efficiency at pH = 0–3 correlated with a number of Phosphinic Acid pendants: NOPO >> NOPA > NO2AP >> NOTA; however, it was more apparent at 95 °C than at room temperature. By contrast, NOTA was found to be labelled more efficiently at pH > 4 compared to the ligands with Phosphinic Acids. Overall, replacement of a single phosphinate donor with a carboxylate does not challenge 68Ga labelling of TRAP-type chelators. However, the presence of carboxylates facilitates labelling at neutral or weakly Acidic pH
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formation and dissociation kinetics of copper ii complexes with tetraphosphorus Acid dota analogs
Polyhedron, 2014Co-Authors: Radek Sevcik, Jakub Vaněk, Přemysl Lubal, Zuzana Kotkova, Jan Kotek, Petr HermannAbstract:Abstract Thermodynamic and kinetic properties of Cu(II) complexes with macrocyclic cyclen-based ligands having four phosphonic Acid monoester (H4dotpOEt = 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrakis(methylphosphonic Acid monoethylester)) or four Phosphinic Acid (H4dotpH = 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrakis(methylPhosphinic Acid and H4dotpPh = 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrakis[methyl(phenyl)Phosphinic Acid]) pendant arms were investigated. The formation kinetics carried out in pH range 1–5.5 (t = 25 °C, I = 0.1 M KCl) shows that reactive species are (H2L)2− and (HL)3− anions and their reactivity differs by 4–5 orders of magnitude. Among studied ligands, H4dotpH is the most reactive one. Dissociation of these copper(II) complexes was investigated in the presence of perchloric Acid (I = 5 M (Na,H)ClO4, proton concentration range 0.1–5.0 M) and in temperature range 10–35 °C. All studied complexes are less kinetically inert than the [Cu(dota)]2− complex and the Cu(II) complex of H4dotpH is the least kinetically inert among the studied complexes, probably due to the lowest thermodynamic stability. These results show that the ligands probably cannot be employed for copper radioisotopes complexation but the data will be utilized in design of other macrocyclic ligands intended to be used in medicinal chemistry.
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complexation of metal ions with trap 1 4 7 triazacyclononane Phosphinic Acid ligands and 1 4 7 triazacyclononane 1 4 7 triacetic Acid phosphinate containing ligands as unique chelators for trivalent gallium
Inorganic Chemistry, 2012Co-Authors: Jakub Simecek, Johannes Notni, Jan Plutnar, Vojtěch Kubicek, J. Havlíčková, Martin Schulz, Petr HermannAbstract:Three Phosphinic Acid 1,4,7-triazacyclononane (TACN) derivatives bearing methylPhosphinic (TRAP-H), methyl(phenyl)Phosphinic (TRAP-Ph), or methyl(hydroxymethyl)Phosphinic Acid (TRAP-OH) pendant arms were investigated as members of a new family of efficient Ga3+ chelators, TRAP ligands (triazacyclononane Phosphinic Acids). Stepwise protonation constants of ligands and stability constants of their complexes with Ga3+, selected divalent metal, and Ln3+ ions were determined by potentiometry. For comparison, equilibrium data for the metal ion–NOTA (1,4,7-triazacyclononane-1,4,7-triacetic Acid) systems were redetermined. These ligands exhibit high thermodynamic selectivity for Ga3+ over the other metal ions (log KGaL – log KML = 7–9) and a selective complexation of smaller Mg2+ over Ca2+. Stabilities of the Ga3+ complexes are dependent on the basicity of the donor atoms: [Ga(NOTA)] (log KGaL = 29.6) > [Ga(TRAP-OH)] (log KGaL = 23.3) > [Ga(TRAP-H)] (log KGaL = 21.9). The [Ga(TRAP-OH)] complex exhibits unusual re...
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derivative of cyclen with three methylene phenyl Phosphinic Acid pendant arms synthesis and crystal structures of its lanthanide complexes
Journal of The Chemical Society-dalton Transactions, 2000Co-Authors: Jan Rohovec, Petr Hermann, Pavel Vojtisek, Jiři Ludvik, Ivan LukesAbstract:A new macrocyclic ligand 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraylmethyltrimethylenetris(phenylPhosphinic Acid) H3L1 was synthesised and its complexes with lanthanides were prepared. X-Ray analysis of seven Ln complexes (Ln = La, Ce, Nd, Eu, Tb, Er, Yb) shows a formation of dimers [LnL1]2 with Phosphinic Acid bridges in the solid state. All complexes are isostructural and the coordination polyhedra are formed by four N atoms and four O atoms of Phosphinic Acid groups. A water molecule is placed near the O4 base. The LnOw distance is strongly dependent on Ln(III), it varies from 2.815(6) A in the La complex to 4.448(10) A in the Yb complex. The 31P NMR studies show formation of a rather complex mixture of isomers in solution. The dimer stability in solution is verified by reaction with triphenylphosphine oxide (tppo) and with pyridine N-oxide and by cyclic voltammetry.
Jon C. Antilla - One of the best experts on this subject based on the ideXlab platform.
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bronsted Acid catalyzed imine amidation
Journal of the American Chemical Society, 2005Co-Authors: Gerald B Rowland, Haile Zhang, Emily B Rowland, Spandan Chennamadhavuni, Jon C. AntillaAbstract:A new method for the Bronsted Acid-catalyzed addition of amide nucleophiles to imines to produce protected aminal products is described. Simple Bronsted Acids (phenyl Phosphinic Acid and trifluoromethanesulfonimide) were shown to be excellent catalysts, providing high yields of the aminal product. A catalytic asymmetric imine amidation using sulfonamides as nucleophiles was successful when a hindered biaryl phosphoric Acid catalyst derived from 2,2‘-diphenyl-[3,3‘-biphenanthrene]-4,4‘-diol (VAPOL) was used. Excellent yields and enantioselectivities were found in these additions (up to 99% ee).
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bronsted Acid catalyzed imine amidation
Journal of the American Chemical Society, 2005Co-Authors: Gerald B Rowland, Haile Zhang, Emily B Rowland, Spandan Chennamadhavuni, Yong Wang, Jon C. AntillaAbstract:A new method for the Bronsted Acid-catalyzed addition of amide nucleophiles to imines to produce protected aminal products is described. Simple Bronsted Acids (phenyl Phosphinic Acid and trifluoromethanesulfonimide) were shown to be excellent catalysts, providing high yields of the aminal product. A catalytic asymmetric imine amidation using sulfonamides as nucleophiles was successful when a hindered biaryl phosphoric Acid catalyst derived from 2,2‘-diphenyl-[3,3‘-biphenanthrene]-4,4‘-diol (VAPOL) was used. Excellent yields and enantioselectivities were found in these additions (up to 99% ee).
Yongqi Zhang - One of the best experts on this subject based on the ideXlab platform.
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yttrium extraction from chloride solution with a synergistic system of 2 ethylhexyl phosphonic Acid mono 2 ethylhexyl ester and bis 2 4 4 trimethylpentyl Phosphinic Acid
Hydrometallurgy, 2014Co-Authors: Can Zhang, Liangshi Wang, Xiaowei Huang, Jinshi Dong, Zhiqi Long, Yongqi ZhangAbstract:Abstract The extraction of yttrium from chloride medium with a mixture of 2-ethylhexyl phosphonic Acid mono-(2-ethylhexyl) ester (HEHEHP, H2A2) and bis(2,4,4-trimethylpentyl) Phosphinic Acid (Cyanex272, H2B2) in kerosene has been studied. The extraction mechanism was determined by the methods of slope analysis and constant mole. The maximum synergistic enhancement factor of 2.94 was obtained at a HEHEHP/Cyanex272 molar ratio of 1:1. It was found that yttrium was extracted with the synergistic system in the form of Y(HB2)(HA2)2. It is very different from the extraction forms of YH2ClA4 and YH2ClB4 when extracted by HEHEHP and Cyanex272 alone system, respectively. The effects of chloride ion on the yttrium extraction were also studied and the extracted complexes in the organic solution were determined by the infrared spectrum method. It was confirmed that the extraction was via a cation exchange mechanism.
Gerald B Rowland - One of the best experts on this subject based on the ideXlab platform.
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bronsted Acid catalyzed imine amidation
Journal of the American Chemical Society, 2005Co-Authors: Gerald B Rowland, Haile Zhang, Emily B Rowland, Spandan Chennamadhavuni, Jon C. AntillaAbstract:A new method for the Bronsted Acid-catalyzed addition of amide nucleophiles to imines to produce protected aminal products is described. Simple Bronsted Acids (phenyl Phosphinic Acid and trifluoromethanesulfonimide) were shown to be excellent catalysts, providing high yields of the aminal product. A catalytic asymmetric imine amidation using sulfonamides as nucleophiles was successful when a hindered biaryl phosphoric Acid catalyst derived from 2,2‘-diphenyl-[3,3‘-biphenanthrene]-4,4‘-diol (VAPOL) was used. Excellent yields and enantioselectivities were found in these additions (up to 99% ee).
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bronsted Acid catalyzed imine amidation
Journal of the American Chemical Society, 2005Co-Authors: Gerald B Rowland, Haile Zhang, Emily B Rowland, Spandan Chennamadhavuni, Yong Wang, Jon C. AntillaAbstract:A new method for the Bronsted Acid-catalyzed addition of amide nucleophiles to imines to produce protected aminal products is described. Simple Bronsted Acids (phenyl Phosphinic Acid and trifluoromethanesulfonimide) were shown to be excellent catalysts, providing high yields of the aminal product. A catalytic asymmetric imine amidation using sulfonamides as nucleophiles was successful when a hindered biaryl phosphoric Acid catalyst derived from 2,2‘-diphenyl-[3,3‘-biphenanthrene]-4,4‘-diol (VAPOL) was used. Excellent yields and enantioselectivities were found in these additions (up to 99% ee).
Can Zhang - One of the best experts on this subject based on the ideXlab platform.
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yttrium extraction from chloride solution with a synergistic system of 2 ethylhexyl phosphonic Acid mono 2 ethylhexyl ester and bis 2 4 4 trimethylpentyl Phosphinic Acid
Hydrometallurgy, 2014Co-Authors: Can Zhang, Liangshi Wang, Xiaowei Huang, Jinshi Dong, Zhiqi Long, Yongqi ZhangAbstract:Abstract The extraction of yttrium from chloride medium with a mixture of 2-ethylhexyl phosphonic Acid mono-(2-ethylhexyl) ester (HEHEHP, H2A2) and bis(2,4,4-trimethylpentyl) Phosphinic Acid (Cyanex272, H2B2) in kerosene has been studied. The extraction mechanism was determined by the methods of slope analysis and constant mole. The maximum synergistic enhancement factor of 2.94 was obtained at a HEHEHP/Cyanex272 molar ratio of 1:1. It was found that yttrium was extracted with the synergistic system in the form of Y(HB2)(HA2)2. It is very different from the extraction forms of YH2ClA4 and YH2ClB4 when extracted by HEHEHP and Cyanex272 alone system, respectively. The effects of chloride ion on the yttrium extraction were also studied and the extracted complexes in the organic solution were determined by the infrared spectrum method. It was confirmed that the extraction was via a cation exchange mechanism.