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Kenneth N. Raymond - One of the best experts on this subject based on the ideXlab platform.
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Terephthalamide-containing ligands: fast removal of iron from transferrin.
Journal of biological inorganic chemistry : JBIC : a publication of the Society of Biological Inorganic Chemistry, 2007Co-Authors: Rebecca J. Abergel, Kenneth N. RaymondAbstract:The mechanism and effectiveness of iron removal from transferrin by three series of new potential therapeutic iron sequestering agents have been analyzed with regard to the structures of the chelators. All compounds are hexadentate ligands composed of a systematically varied combination of methyl-3,2-hydroxypyridinone (Me-3,2-HOPO) and 2,3-dihydroxyTerephthalamide (TAM) binding units linked to a polyamine scaffold through amide linkers; each series is based on a specific backbone: tris(2-aminoethyl)amine, spermidine, or 5-LIO(TAM), where 5-LIO is 2-(2-aminoethoxy)ethylamine. Rates of iron removal from transferrin were determined spectrophotometrically for the ten ligands, which all efficiently acquire ferric ion from diferric transferrin with a hyperbolic dependence on ligand concentration (saturation kinetics). The effect of the two iron-binding subunits Me-3,2-HOPO and TAM and of the scaffold structures on iron removal ability is discussed. At the low concentrations corresponding to therapeutic dose, TAM-containing ligands exhibit the fastest rates of iron removal, which correlates with their high affinity for ferric ion and suggests the insertion of such binding units into future therapeutic chelating agents. In addition, urea polyacrylamide gel electrophoresis was used to measure the individual microscopic rates of iron removal from the three iron-bound transferrin species (diferric transferrin, N-terminal monoferric transferrin, C-terminal monoferric transferrin) by the representative chelators 5-LIO(Me-3,2-HOPO)2(TAM) and 5-LIO(TAMmeg)2(TAM), where TAMmeg is 2,3-dihydroxy-1-(methoxyethylcarbamoyl)Terephthalamide. Both ligands show preferential removal from the C-terminal site of the iron-binding protein. However, cooperative effects between the two binding sites differ with the chelator. Replacement of hydroxypyridinone moieties by Terephthalamide groups renders the N-terminal site more accessible to the ligand and may represent an advantage for iron chelation therapy.
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Synthesis and Thermodynamic Evaluation of Mixed Hexadentate Linear Iron Chelators Containing Hydroxypyridinone and Terephthalamide Units
Inorganic chemistry, 2006Co-Authors: Rebecca J. Abergel, Kenneth N. RaymondAbstract:A series of new linear iron chelators containing hydroxypyridinone and Terephthalamide (TAMmeg) moieties have been prepared. All are hexadentate ligands composed of a systematically varied combination of methyl-3,2-hydroxypyridinone and 2,3-dihydroxyTerephthalamide binding units; most are based on a spermidine scaffold, but one incorporates the bifunctional 2,3-dihydroxyTerephthalamide unit as an integral part of the backbone. Protonation and ferric iron complex formation constants have been determined from solution thermodynamic studies, giving log beta(110) values of 25.7, 30.7, 36.3, 43.8, and 45.0, respectively. The ferric complexes display reversible reduction potentials from -276 to -1032 mV (measured relative to the normal hydrogen electrode) in alkaline solution. The incremental replacement of hydroxypyridinone units by Terephthalamide binding groups progressively reduces the ligand acidity, markedly increases the iron-chelate stability, and improves the selectivity for the ferric ion over the ferrous ion. While the majority of iron chelators forming very stable ferric complexes are based on a tripodal backbone such as TREN, the ferric 5-LIO(TAMmeg)(2)(TAM) complex, despite its nontripodal scaffold, is one of the most stable iron complexes yet reported. Moreover, the high affinity for the ferric ion of the discussed linear ligands strongly correlates with their ability to remove iron in vivo.
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A bidentate Terephthalamide ligand, TAMmeg, as an entry into Terephthalamide-containing therapeutic iron chelating agents.
Inorganic chemistry, 2006Co-Authors: Kristy M. Clarke Jurchen, Kenneth N. RaymondAbstract:A new bidentate 2,3-dihydroxyTerephthalamide ligand, 2,3-dihydroxy-N,N'-bis(2-methoxyethyl)Terephthalamide (TAMmeg), has been prepared. The ligand, its synthetic precursor 2,3-bis(benzyloxy)-N,N'-bis(2-methoxy-ethyl)-Terephthalamide (BnTAMmeg), and its iron complex have been structurally characterized by X-ray diffraction. BnTAMmeg crystallizes in the monoclinic space group P2(1)/n with cell parameters a = 14.4976(14) A, b = 11.5569(11) A, c = 16.3905(16) A, beta = 113.621(1) degrees , and Z = 4. TAMmeg crystallizes in the monoclinic space group P2(1)/c with cell parameters a = 13.8060(36) A, b = 8.0049(21) A, c = 19.4346(50) A, beta = 106.855(4) degrees , and Z = 4. Fe[TAMmeg] crystallizes in the triclinic space group P with cell parameters a = 12.9565(14) A, b = 13.4514(14) A, c = 20.2092(21) A, alpha = 102.093(2) degrees , beta = 95.433(2) degrees , gamma = 101.532(2) degrees , and Z = 2. The aqueous protonation and ferric ion coordination chemistry of TAMmeg were examined using potentiometric and spectrophotometric methods. Proton association constants and iron complex formation constants for the ligand are as follows: log beta(011) = 10.32, log beta(012) = 16.49, log beta(110) = 17.9, log beta(120) = 32.1, and log beta(130) = 43.0. The ferric complex of TAMmeg is surprisingly stable for a bidentate Terephthalamide iron complex. The only more-stable bidentate Terephthalamide iron complex that has been reported contains a ligand with positively charged pendant arms.
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a bidentate Terephthalamide ligand tammeg as an entry into Terephthalamide containing therapeutic iron chelating agents
Inorganic Chemistry, 2006Co-Authors: Kristy M. Clarke Jurchen, Kenneth N. RaymondAbstract:A new bidentate 2,3-dihydroxyTerephthalamide ligand, 2,3-dihydroxy-N,N‘-bis(2-methoxyethyl)Terephthalamide (TAMmeg), has been prepared. The ligand, its synthetic precursor 2,3-bis(benzyloxy)-N,N‘-bis(2-methoxy-ethyl)-Terephthalamide (BnTAMmeg), and its iron complex have been structurally characterized by X-ray diffraction. BnTAMmeg crystallizes in the monoclinic space group P21/n with cell parameters a = 14.4976(14) A, b = 11.5569(11) A, c = 16.3905(16) A, β = 113.621(1)°, and Z = 4. TAMmeg crystallizes in the monoclinic space group P21/c with cell parameters a = 13.8060(36) A, b = 8.0049(21) A, c = 19.4346(50) A, β = 106.855(4)°, and Z = 4. Fe[TAMmeg] crystallizes in the triclinic space group P1 with cell parameters a = 12.9565(14) A, b = 13.4514(14) A, c = 20.2092(21) A, α = 102.093(2)°, β = 95.433(2)°, γ = 101.532(2)°, and Z = 2. The aqueous protonation and ferric ion coordination chemistry of TAMmeg were examined using potentiometric and spectrophotometric methods. Proton association constants and ir...
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Terephthalamide-containing analogues of TREN-Me-3,2-HOPO.
Inorganic chemistry, 2006Co-Authors: Kristy M. Clarke Jurchen, Kenneth N. RaymondAbstract:A series of Terephthalamide-containing analogues based on TREN-Me-3,2-HOPO have been prepared. These analogues contain one, two, or three bidentate 2,3-dihydroxyTerephthalamide (TAM) units in place of the 3,2-hydroxypyridinone (HOPO) units on the parent hexadentate ligand. One representative ligand in the series, TRENHOPOTAM2, and its gallium complex have been structurally characterized by X-ray diffraction. TRENHOPOTAM2 crystallizes in the monoclinic space group P2(1)/c with cell parameters a = 16.0340(17) A, b = 17.0609(18) A, c = 16.0695(17) A, beta = 113.837(2) degrees, and Z = 4. Ga[TRENHOPOTAM2] also crystallizes in the monoclinic space group P2(1)/c, with cell parameters a = 16.3379(14) A, b = 15.2722(13) A, c = 19.4397(17) A, beta = 91.656(2) degrees, and Z = 4. The conformation of the TRENHOPOTAM2 ligand structure suggests that the ligand is predisposed for metal ion binding. The aqueous protonation and ferric ion coordination chemistry of all ligands in the series were examined using potentiometric and spectrophotometric methods, giving log formation constants of 34.6(2) (beta110) and 38.8(2) (beta111) for the ferric TRENHOPO2TAM complexes, 41.0(3) (beta110) and 45.4(3) (beta111) for the ferric TRENHOPOTAM2 complexes, and 45.2(2) (beta110) and 50.9(2) (beta111) for the ferric TRENTAM3 complexes. These thermodynamic data confirm that adding Terephthalamide units to a hydroxypyridinone-containing ligand tends to increase the stability of the resulting iron complex. The ferric TRENTAM3 complex is one of the most stable iron complexes yet reported.
Kai-rhen Shiao - One of the best experts on this subject based on the ideXlab platform.
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Mechanical behaviour of block copolymers of polyurethane with poly (4,4′-diphenylsulphone Terephthalamide)
Journal of Materials Science, 1995Co-Authors: Ming-fung Lin, Huei-hsiung Wang, Kai-rhen ShiaoAbstract:Two poly (tetramethylene glycols) (PTMG), molecular weight of 650 and 2000, with 4,4′-diphenylmethane diisocyanate (MDI) and poly(4, 4′-diphenylsulphone Terephthalamide) (PSA) prepolymer were polycondensated. Four different molar ratios of PTMG, MDI and PSA prepolymer were synthesized to form eight PU-PSA block copolymers. The mechanical properties including stress-strain and stress-relaxation measurements of each copolymer were discussed. The determined values of Young's modulus E, Mooney-Rivlin relation elastic parameters C1 and C2, relaxation moduli E1(0) and E2(0), relaxation time τ1 and τ2 were used to estimate the effect of hard segment and soft segment domains on the mechanical behaviour of copolymers. It was found that PU-PSA block copolymers apparently displayed elastic properties, especially using the molecular weight 2000 of PTMG which exhibited more elastic behaviour.
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Morphologies and mechanical properties of polyblends of polyurethane with poly(4,4?-diphenylsulphone Terephthalamide)
Journal of Materials Science, 1992Co-Authors: Kai-rhen Shiao, Huei-hsiung WangAbstract:Two polyurethane (PU) elastomers were blended physically with various ratios of poly(4,4′-diphenylsulphone Terephthalamide) (PSA) to form eight PU/PSA polyblends in order to modify their mechanical properties. The stress-strain and stress-relaxation behaviour of PU/PSA polyblends were studied. The measured values of Young's modulus,E, Mooney-Rivlin elastic parameters, C1 and C2, relaxation moduli,E(10 s) andE(100 s), as well as relaxation speed,V r , were used to estimate the effect of semi-rigid PSA molecules on the mechanical behaviour of polyblends. It was found that PU/PSA polyblends still displayed good elastic properties, although PU/PSA polyblends had a dispersed phase structure. At lower of PSA contents (below 10 wt % PSA), PU/PSA polyblends showed improved stress-relaxation properties.
Kristy M. Clarke Jurchen - One of the best experts on this subject based on the ideXlab platform.
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A bidentate Terephthalamide ligand, TAMmeg, as an entry into Terephthalamide-containing therapeutic iron chelating agents.
Inorganic chemistry, 2006Co-Authors: Kristy M. Clarke Jurchen, Kenneth N. RaymondAbstract:A new bidentate 2,3-dihydroxyTerephthalamide ligand, 2,3-dihydroxy-N,N'-bis(2-methoxyethyl)Terephthalamide (TAMmeg), has been prepared. The ligand, its synthetic precursor 2,3-bis(benzyloxy)-N,N'-bis(2-methoxy-ethyl)-Terephthalamide (BnTAMmeg), and its iron complex have been structurally characterized by X-ray diffraction. BnTAMmeg crystallizes in the monoclinic space group P2(1)/n with cell parameters a = 14.4976(14) A, b = 11.5569(11) A, c = 16.3905(16) A, beta = 113.621(1) degrees , and Z = 4. TAMmeg crystallizes in the monoclinic space group P2(1)/c with cell parameters a = 13.8060(36) A, b = 8.0049(21) A, c = 19.4346(50) A, beta = 106.855(4) degrees , and Z = 4. Fe[TAMmeg] crystallizes in the triclinic space group P with cell parameters a = 12.9565(14) A, b = 13.4514(14) A, c = 20.2092(21) A, alpha = 102.093(2) degrees , beta = 95.433(2) degrees , gamma = 101.532(2) degrees , and Z = 2. The aqueous protonation and ferric ion coordination chemistry of TAMmeg were examined using potentiometric and spectrophotometric methods. Proton association constants and iron complex formation constants for the ligand are as follows: log beta(011) = 10.32, log beta(012) = 16.49, log beta(110) = 17.9, log beta(120) = 32.1, and log beta(130) = 43.0. The ferric complex of TAMmeg is surprisingly stable for a bidentate Terephthalamide iron complex. The only more-stable bidentate Terephthalamide iron complex that has been reported contains a ligand with positively charged pendant arms.
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a bidentate Terephthalamide ligand tammeg as an entry into Terephthalamide containing therapeutic iron chelating agents
Inorganic Chemistry, 2006Co-Authors: Kristy M. Clarke Jurchen, Kenneth N. RaymondAbstract:A new bidentate 2,3-dihydroxyTerephthalamide ligand, 2,3-dihydroxy-N,N‘-bis(2-methoxyethyl)Terephthalamide (TAMmeg), has been prepared. The ligand, its synthetic precursor 2,3-bis(benzyloxy)-N,N‘-bis(2-methoxy-ethyl)-Terephthalamide (BnTAMmeg), and its iron complex have been structurally characterized by X-ray diffraction. BnTAMmeg crystallizes in the monoclinic space group P21/n with cell parameters a = 14.4976(14) A, b = 11.5569(11) A, c = 16.3905(16) A, β = 113.621(1)°, and Z = 4. TAMmeg crystallizes in the monoclinic space group P21/c with cell parameters a = 13.8060(36) A, b = 8.0049(21) A, c = 19.4346(50) A, β = 106.855(4)°, and Z = 4. Fe[TAMmeg] crystallizes in the triclinic space group P1 with cell parameters a = 12.9565(14) A, b = 13.4514(14) A, c = 20.2092(21) A, α = 102.093(2)°, β = 95.433(2)°, γ = 101.532(2)°, and Z = 2. The aqueous protonation and ferric ion coordination chemistry of TAMmeg were examined using potentiometric and spectrophotometric methods. Proton association constants and ir...
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Terephthalamide-containing analogues of TREN-Me-3,2-HOPO.
Inorganic chemistry, 2006Co-Authors: Kristy M. Clarke Jurchen, Kenneth N. RaymondAbstract:A series of Terephthalamide-containing analogues based on TREN-Me-3,2-HOPO have been prepared. These analogues contain one, two, or three bidentate 2,3-dihydroxyTerephthalamide (TAM) units in place of the 3,2-hydroxypyridinone (HOPO) units on the parent hexadentate ligand. One representative ligand in the series, TRENHOPOTAM2, and its gallium complex have been structurally characterized by X-ray diffraction. TRENHOPOTAM2 crystallizes in the monoclinic space group P2(1)/c with cell parameters a = 16.0340(17) A, b = 17.0609(18) A, c = 16.0695(17) A, beta = 113.837(2) degrees, and Z = 4. Ga[TRENHOPOTAM2] also crystallizes in the monoclinic space group P2(1)/c, with cell parameters a = 16.3379(14) A, b = 15.2722(13) A, c = 19.4397(17) A, beta = 91.656(2) degrees, and Z = 4. The conformation of the TRENHOPOTAM2 ligand structure suggests that the ligand is predisposed for metal ion binding. The aqueous protonation and ferric ion coordination chemistry of all ligands in the series were examined using potentiometric and spectrophotometric methods, giving log formation constants of 34.6(2) (beta110) and 38.8(2) (beta111) for the ferric TRENHOPO2TAM complexes, 41.0(3) (beta110) and 45.4(3) (beta111) for the ferric TRENHOPOTAM2 complexes, and 45.2(2) (beta110) and 50.9(2) (beta111) for the ferric TRENTAM3 complexes. These thermodynamic data confirm that adding Terephthalamide units to a hydroxypyridinone-containing ligand tends to increase the stability of the resulting iron complex. The ferric TRENTAM3 complex is one of the most stable iron complexes yet reported.
Huei-hsiung Wang - One of the best experts on this subject based on the ideXlab platform.
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Mechanical behaviour of block copolymers of polyurethane with poly (4,4′-diphenylsulphone Terephthalamide)
Journal of Materials Science, 1995Co-Authors: Ming-fung Lin, Huei-hsiung Wang, Kai-rhen ShiaoAbstract:Two poly (tetramethylene glycols) (PTMG), molecular weight of 650 and 2000, with 4,4′-diphenylmethane diisocyanate (MDI) and poly(4, 4′-diphenylsulphone Terephthalamide) (PSA) prepolymer were polycondensated. Four different molar ratios of PTMG, MDI and PSA prepolymer were synthesized to form eight PU-PSA block copolymers. The mechanical properties including stress-strain and stress-relaxation measurements of each copolymer were discussed. The determined values of Young's modulus E, Mooney-Rivlin relation elastic parameters C1 and C2, relaxation moduli E1(0) and E2(0), relaxation time τ1 and τ2 were used to estimate the effect of hard segment and soft segment domains on the mechanical behaviour of copolymers. It was found that PU-PSA block copolymers apparently displayed elastic properties, especially using the molecular weight 2000 of PTMG which exhibited more elastic behaviour.
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Morphologies and mechanical properties of polyblends of polyurethane with poly(4,4?-diphenylsulphone Terephthalamide)
Journal of Materials Science, 1992Co-Authors: Kai-rhen Shiao, Huei-hsiung WangAbstract:Two polyurethane (PU) elastomers were blended physically with various ratios of poly(4,4′-diphenylsulphone Terephthalamide) (PSA) to form eight PU/PSA polyblends in order to modify their mechanical properties. The stress-strain and stress-relaxation behaviour of PU/PSA polyblends were studied. The measured values of Young's modulus,E, Mooney-Rivlin elastic parameters, C1 and C2, relaxation moduli,E(10 s) andE(100 s), as well as relaxation speed,V r , were used to estimate the effect of semi-rigid PSA molecules on the mechanical behaviour of polyblends. It was found that PU/PSA polyblends still displayed good elastic properties, although PU/PSA polyblends had a dispersed phase structure. At lower of PSA contents (below 10 wt % PSA), PU/PSA polyblends showed improved stress-relaxation properties.
David M. Hercules - One of the best experts on this subject based on the ideXlab platform.
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MALDI-TOF MS stability study of model poly(p-phenylene Terephthalamide)s.
Analytical and bioanalytical chemistry, 2009Co-Authors: Anthony P. Gies, Anton Schotman, David M. HerculesAbstract:In the present study, we address the possibility of matrix-assisted laser desorption/ionization (MALDI)–time-of-flight MS analysis-induced chain fragmentation in poly(p-phenylene Terephthalamide) (PPD-T) by considering two possible sources: (1) grinding-induced fragmentation resulting from the evaporation–grinding MALDI sample preparation method (E-G method) and (2) in-source/metastable fragmentation induced by the MALDI laser. An analysis of variance (ANOVA) statistical study found, with a high probability, that obtaining MALDI spectra with the effective laser area as large as possible (the “fanned-out” setting) did not cause any chain fragmentation due to the E-G MALDI sample preparation method, even when three additional grinding steps were used. However, the effect of laser fluence was less clear. A significant effect of laser fluence was observed for lower mass oligomers (
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MALDI-TOF MS Study of Poly(p-phenylene Terephthalamide) Fibers
Macromolecules, 2006Co-Authors: Anthony P. Gies And, David M. Hercules, Sparkle T. Ellison And, William K. NonidezAbstract:MALDI-TOF MS was used to study the end group distribution of a series of poly(p-phenylene Terephthalamide) and Kevlar fibers. Poly(p-phenylene Terephthalamide) fibers were synthesized using various percent mole ratios of diamine-to-diacid chloride (70:30, 51:49, 50:50, 49:51, and 30:70), and their resulting MALDI-TOF mass spectra were compared with the mass spectra of Kevlar fibers. Oligomers synthesized with excess diamine or excess diacid chloride were found to contain abundances of amine or carboxylate end groups, respectively, along with side products that were specific to their synthesis. Oligomers synthesized with near equimolar ratios of reactants produced dominant species with amine-carboxyl end groups along with small quantities of cyclic and imine branched species, which were also found in the oligomeric portion of commercially produced Kevlar. Experimental results from this study indicate that mass spectra derived from the oligomeric portion of high molecular weight polymers can yield useful in...
