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Petr Hermann - One of the best experts on this subject based on the ideXlab platform.
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coordination properties of cyclam 1 4 8 11 tetraazacyclotetradecane endowed with two Methylphosphonic Acid pendant arms in the 1 4 positions
Dalton Transactions, 2008Co-Authors: Jana Havlickova, Jan Kotek, Ivana Cisařova, Tomas Vitha, Hana Medova, Petr HermannAbstract:The title ligand, 1,4,8,11-tetraazacyclotetradecane-1,4-diyl-bis(Methylphosphonic Acid) (H4te2p1,4, H4L), was prepared by an optimized synthetic approach and its complexing properties towards selected metal ions were studied by means of potentiometry. The ligand forms a very stable complex with copper(II) (log β(CuL) = 27.21), with a high selectivity over binding of other metal ions (e.g. log β(ZnL) = 20.16, log β(NiL) = 21.92). The crystal structures of two intermediates in the ligand synthesis and two forms of the nickel(II) complex (obtained by crystallization at different pH) were determined. From Acid solution, the crystals of trans-O,O-[Ni(H3L)]Cl·H2O were isolated. In such complex species, one phosphonate pendant arm is double- and the second arm is monoprotonated. The isolation of such species demonstrates a high kinetic inertness of the complex. The central metal ion is surrounded by four in-plane nitrogen atoms (in the ring configuration III) and two oxygen atoms of pendant moieties in the apical positions of octahedral coordination sphere. From neutral solution, the crystals of {trans-O,O-[Ni(H2L)]}3·5H2O were isolated. The molecular structures of the complex units found in this structure are analogous to that found in trans-O,O-[Ni(H3L)]Cl·H2O.
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chemical and biological evaluation of 153sm and 166ho complexes of 1 4 7 10 tetraazacyclododecane 1 4 7 10 tetrakis Methylphosphonic Acid monoethylester h4dotpoet
Journal of Inorganic Biochemistry, 2008Co-Authors: Michaela Forsterova, Petr Hermann, Přemysl Lubal, Zuzana Jandurova, Fernanda Marques, Lurdes Gano, Jakub Vaněk, Isabel SantosAbstract:The novel Methylphosphonic Acid monoethylester (H4dotpOEt) has been synthesized and characterized and their complexes with Sm(III) and Ho(III) ions were studied. Dissociation constants of the ligand are lower than those of H4dota. The stability constants of the Ln(III)-H4dotpOEt complexes are surprisingly much lower that those of H4dota probably due to a lower coordination ability of the phosphonate monoester groups. Acid-assisted decomplexation studies have shown that both complexes are less kinetically inert than the H4dota complexes, but still much more inert than complexes of open-chain ligands. Nevertheless, the synthesis of 153Sm and 166Ho complexes with this ligand led to stable complexes both in vitro and in vivo. A very low binding of these complexes to hydroxyapatite (HA) and calcified tissues was observed confirming the assumption that a fully ionized phosphonate group(s) is necessary for a strong bone affinity. Both complexes show similar behaviour in vivo.
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thermodynamic kinetic and solid state study of divalent metal complexes of 1 4 8 11 tetraazacyclotetradecane cyclam bearing two trans 1 8 Methylphosphonic Acid pendant arms
Dalton Transactions, 2006Co-Authors: Ivona Svobodova, Jan Kotek, Petr Hermann, Přemysl Lubal, Jana Havlickova, Jan Plutnar, Ivan LukesAbstract:Divalent metal complexes of macrocyclic ligand 1,4,8,11-tetraazacyclotetradecane-1,8-bis(Methylphosphonic Acid)) (1,8-H4te2p, H4L) were investigated in solution and in the solid state. The majority of transition-metal ions form thermodynamically very stable complexes as a consequence of high affinity for the nitrogen atoms of the ring. On the other hand, complexes with Mn2+, Pb2+ and alkaline earth ions interacting mainly with phosphonate oxygen atoms are much weaker than those of transition-metal ions and are formed only at higher pH. The same tendency is seen in the solid state. Zinc(II) ion in the octahedral trans-O,O-[Zn(H2L)] complex is fully encapsulated within the macrocycle (N4O2 coordination mode with protonated phosphonate oxygen atoms). The polymeric {[Pb(H2L)(H2O)2]·6H2O}n complex has double-protonated secondary amino groups and the central atom is bound only to the phosphonate oxygen atoms. The phosphonate moieties bridge lead atoms creating a 3D-polymeric network. The [{(H2O)5Mn}2(µ-H2L)](H2L)·21H2O complex contains two pentaaquamanganese(II) moieties bridged by a ligand molecule protonated on two nitrogen atoms. In the complex cation, oxygen atoms of the phosphonate groups on the opposite sites of the ring occupy one coordination site of each metal ion. The second ligand molecule is diprotonated and balances the positive charge of the complex cation. Complexation of zinc(II) and cadmium(II) by the ligand shows large differences in reactivity of differently protonated ligand species similarly to other cyclam-like complexes. Acid-assisted dissociations of metal(II) complexes occur predominantly through triprotonated species [M(H3L)]+ and take place at pH < 5 (Zn2+) and pH < 6 (Cd2+).
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selective protection of 1 4 8 11 tetraazacyclotetradecane cyclam in position 1 4 with the phosphonothioyl group and synthesis of a cyclam 1 4 bis Methylphosphonic Acid crystal structures of several cyclic phosphonothioamides
Collection of Czechoslovak Chemical Communications, 2006Co-Authors: Tomas Vitha, Jan Kotek, Petr Hermann, Ivana Cisařova, Jakub Rudovský, Vojtěch Kubicek, Ivan LukesAbstract:A new cyclam-based ligand, 1,4,8,11-tetraazacyclotetradecane-1,4-bis(Methylphosphonic Acid) (1,4-H4te2p), was synthesized. Cyclam was protected by the reaction with PhP(S)Cl2 to form exclusively five-membered cyclic phenylphosphonothioic diamide 2 in a moderate yield. The solid-state structures of 2 and several by-products were determined. Compound 2 was isolated as two stable conformers differing in a mutual position of benzene ring and sulfur atom with respect to the cyclam ring. Compound 2 was used for the synthesis of 1,4-dibenzylcyclam. However, the deprotection of the thiophosphoryl-protected bis(methylphosphonate diester) with aqueous HCl under non-optimized conditions led to a mixture of cyclam derivatives differently substituted with Methylphosphonic Acid groups. The crystal structures of the target product, 1,4-H4te2p, and also 1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetrakis(Methylphosphonic Acid) (H8tetp) were determined. A similar reaction with cyclen (1,4,7,10-tetraazacyclododecane) led only to hardly purifiable mixtures.
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application of dipon 1 4 8 11 tetraazacyclotetradecane 4 11 bis Methylphosphonic Acid as selective complexing agent for determination of copper ii
Journal of Inclusion Phenomena and Macrocyclic Chemistry, 2004Co-Authors: Ivona Svobodova, Jan Kotek, Petr Hermann, Přemysl Lubal, Josef HavelAbstract:A new macrocyclic ligand, 1,4,8,11-tetraazacyclotetradecane-1,8-bis(Methylphosphonic Acid)(dipon), is selective complexing agent for copper(II) over other transition metal ions. The ligand was tested for analytical applications of copper(II) determination. Spectrophotometric determination under optimal experimental conditions (−log [H+]= 5.5, cL≈ 5 × 10−4 mol L−1, λ= 310 nm) is valid in dynamic range (5–200)× 10−6 mol L−1 with detection limit 2.2 × 10−6 mol L−1, i.e. 0.14 μg ml−1. Volumetric determination of copper(II) with standardized dipon solution was used for copper(II) determination at micromolar concentration level without any necessity to sequester interfering metal ions. A sharp end point of titration was detected by UV/VIS spectrophotometry. Both methods were tested on artificial and real samples (spiked mineral water, alloys) and gave satisfactory results without any systematic error. The advantage of both methods is their simplicity, rapidity and no sensitivity to the presence of other metal ions.
Ivan Lukes - One of the best experts on this subject based on the ideXlab platform.
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thermodynamic kinetic and solid state study of divalent metal complexes of 1 4 8 11 tetraazacyclotetradecane cyclam bearing two trans 1 8 Methylphosphonic Acid pendant arms
Dalton Transactions, 2006Co-Authors: Ivona Svobodova, Jan Kotek, Petr Hermann, Přemysl Lubal, Jana Havlickova, Jan Plutnar, Ivan LukesAbstract:Divalent metal complexes of macrocyclic ligand 1,4,8,11-tetraazacyclotetradecane-1,8-bis(Methylphosphonic Acid)) (1,8-H4te2p, H4L) were investigated in solution and in the solid state. The majority of transition-metal ions form thermodynamically very stable complexes as a consequence of high affinity for the nitrogen atoms of the ring. On the other hand, complexes with Mn2+, Pb2+ and alkaline earth ions interacting mainly with phosphonate oxygen atoms are much weaker than those of transition-metal ions and are formed only at higher pH. The same tendency is seen in the solid state. Zinc(II) ion in the octahedral trans-O,O-[Zn(H2L)] complex is fully encapsulated within the macrocycle (N4O2 coordination mode with protonated phosphonate oxygen atoms). The polymeric {[Pb(H2L)(H2O)2]·6H2O}n complex has double-protonated secondary amino groups and the central atom is bound only to the phosphonate oxygen atoms. The phosphonate moieties bridge lead atoms creating a 3D-polymeric network. The [{(H2O)5Mn}2(µ-H2L)](H2L)·21H2O complex contains two pentaaquamanganese(II) moieties bridged by a ligand molecule protonated on two nitrogen atoms. In the complex cation, oxygen atoms of the phosphonate groups on the opposite sites of the ring occupy one coordination site of each metal ion. The second ligand molecule is diprotonated and balances the positive charge of the complex cation. Complexation of zinc(II) and cadmium(II) by the ligand shows large differences in reactivity of differently protonated ligand species similarly to other cyclam-like complexes. Acid-assisted dissociations of metal(II) complexes occur predominantly through triprotonated species [M(H3L)]+ and take place at pH < 5 (Zn2+) and pH < 6 (Cd2+).
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selective protection of 1 4 8 11 tetraazacyclotetradecane cyclam in position 1 4 with the phosphonothioyl group and synthesis of a cyclam 1 4 bis Methylphosphonic Acid crystal structures of several cyclic phosphonothioamides
Collection of Czechoslovak Chemical Communications, 2006Co-Authors: Tomas Vitha, Jan Kotek, Petr Hermann, Ivana Cisařova, Jakub Rudovský, Vojtěch Kubicek, Ivan LukesAbstract:A new cyclam-based ligand, 1,4,8,11-tetraazacyclotetradecane-1,4-bis(Methylphosphonic Acid) (1,4-H4te2p), was synthesized. Cyclam was protected by the reaction with PhP(S)Cl2 to form exclusively five-membered cyclic phenylphosphonothioic diamide 2 in a moderate yield. The solid-state structures of 2 and several by-products were determined. Compound 2 was isolated as two stable conformers differing in a mutual position of benzene ring and sulfur atom with respect to the cyclam ring. Compound 2 was used for the synthesis of 1,4-dibenzylcyclam. However, the deprotection of the thiophosphoryl-protected bis(methylphosphonate diester) with aqueous HCl under non-optimized conditions led to a mixture of cyclam derivatives differently substituted with Methylphosphonic Acid groups. The crystal structures of the target product, 1,4-H4te2p, and also 1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetrakis(Methylphosphonic Acid) (H8tetp) were determined. A similar reaction with cyclen (1,4,7,10-tetraazacyclododecane) led only to hardly purifiable mixtures.
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high thermodynamic stability and extraordinary kinetic inertness of copper ii complexes with 1 4 8 11 tetraazacyclotetradecane 1 8 bis Methylphosphonic Acid example of a rare isomerism between kinetically inert penta and hexacoordinated copper ii complexes
Chemistry: A European Journal, 2003Co-Authors: Jan Kotek, Petr Hermann, Ivan Lukes, Ivana Cisařova, Ivona Svobodova, Přemysl Lubal, Tomas Godula, Petr Taborský, Josef HavelAbstract:In an aqueous solution at room temperature, 1,4,8,11-tetraazacyclotetradecane-1,8-bis(Methylphosphonic Acid) (H4L1) and CuII form a pentacoordinated (pc) complex, pc-[Cu(L1)]2-, exhibiting conformation I of the cyclam ring. At high temperature, the complex isomerises to a hexacoordinated isomer, trans-O,O-[Cu(L1)]2-, with a trans-III[Note ] conformation of the cyclam ring. In pc-[Cu(L1)]2-, four ring nitrogen atoms and one phosphonate oxygen atom are arranged around CuII in a structure that is half-way between a trigonal bipyramid and a tetragonal pyramid, with one phosphonic Acid group uncoordinated. In the trans-O,O-[Cu(L1)]2- isomer, the nitrogen atoms form a plane and the phosphonic Acid groups are in a mutually trans configuration. A structurally very similar ligand, 4-methyl-1,4,8,11-tetraazacyclotetradecane-1,8-bis(methylphosph onic Acid) (H4L2), forms an analogous pentacoordinated complex, pc-[Cu(L2)]2-, at room temperature. However, the complex does not isomerise to the octahedral complex analogous to trans-O,O-[Cu(L1)]2-. Because of the high thermodynamic stability of pc-[Cu(L1)]2-, (log =25.40(4), 25 degrees of Celsius, I=0.1 mol dm-3 KNO3) and the formation of protonated species, CuII is fully complexed in Acidic solution (-log [H+] ~ 3). Acid-assisted decomplexation of both of the isomers of [Cu(H2L1)] takes place only after protonation of both uncoordinated oxygen atoms of each phosphonate moiety and at least one nitrogen atom of the cycle. The exceptional kinetic inertness of both isomers is illustrated by their half-lives 1/2=19.7 min for pc-[Cu(H2L1)] and about seven months for trans-O,O-[Cu(H2L1)] for decomplexation in 5 M HClO4 at 25 degrees of Celsius. The mechanism of formation of pc-[Cu(L1)]2- is similar to those observed for other macrocyclic complexes.
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the cis trans isomerism on cobalt iii complexes with 1 4 8 11 tetraazacyclotetradecane 1 8 bis Methylphosphonic Acid
Inorganica Chimica Acta, 2001Co-Authors: Jan Kotek, Ivana Cisařova, Petr Hermann, Jan Rohovec, Ivan LukesAbstract:Abstract The X-ray structure determinations show that 1,4,8,11-tetraazacyclotetradecane-1,8-bis(Methylphosphonic) Acid H4L forms both cis- and trans-O,O isomeric complexes with Co(III). Orientation of the other donor atoms indicates the formation of cis-O1,O2-trans-N1,N8-cis-O1,N4-[Co(HL)]. The kinetically preferred cis-isomer is easily formed due to the strong hydrogen bond between the neighboring phosphonic Acid groups. The presence of the hydrogen bond in aqueous solution is confirmed by the value of pKa which increases by four orders of magnitude in comparison with the trans-isomer. Formation of the trans-[Co(HL)] occurs only after long heating of a Co(II) solution with the ligand under inert atmosphere before oxidation, which is explained by insertion of the Co(II) ion in the plane of nitrogen atoms of 1,4,8,11-tetraazacyclotetradecane.
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unusual cis trans isomerism in octahedral nickel ii complexes with 1 4 8 11 tetraazacyclotetradecane 1 8 bis Methylphosphonic Acid as a ligand
Collection of Czechoslovak Chemical Communications, 2001Co-Authors: Jan Kotek, Pavel Vojtisek, Ivana Cisařova, Petr Hermann, Ivan LukesAbstract:Nickel(II) ion reacts with 1,4,8,11-tetraazacyclotetradecane-1,8-bis(Methylphosphonic Acid) (H4L1) at room temperature with formation of cis-[Ni(L1)]2- complex. The complex was crystallised in several forms in dependence on conditions of isolation (temperature, pH, solvent mixture). Crystal structures of cis-O,O-[Ni(H2L1)] (1), cis-O,O-[Ni(H2L1)]·2H2O (2), cis-O,O-[Ni(H3L1)]Cl·H2O (3) and cis-O,O-[Ni(H4L1)]Cl2·2H2O (4) were determined by X-ray diffraction. In all the compounds, Ni2+ is in octahedral cis-O1,O2-trans-N1,N8-cis-O1,N4-[Ni(L1)]2- (hereafter abbreviated as cis-O,O-[Ni(L1)]2-) arrangement with V conformation of the cyclam ring. Complexes 3 and 4 exhibit very unusual coordination through the phosphoryl group of double-protonated phosphonate moiety. Tetraethylester of H4L1 having only poorly coordinating phosphoryl oxygen atoms also forms nickel(II) complex 5 with cis arrangement. Corresponding trans-O,O-[Ni(L1)]2- complex is formed only in strongly Acidic medium through conversion of the cis complex; it was characterised by X-ray diffraction as dihydrochloride dihydrate, trans-O,O-[Ni(H4L1)]Cl2·2H2O (6). The analogous compound (NH4)2(trans-O,O-[Ni(L2)])·H2O (7) is obtained quantitatively by reaction of Ni2+ with 4,11-dibenzyl-1,4,8,11-tetraazacyclotetradecane-1,8-bis(Methylphosphonic Acid) (H4L2). Formation of this complex 7 in the III cyclam ring conformation is preferred to the cis complex due to steric hindrance of bulky benzyl groups in cis-[Ni(L2)]2- complex with the V cyclam ring conformation.
Jan Kotek - One of the best experts on this subject based on the ideXlab platform.
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coordination properties of cyclam 1 4 8 11 tetraazacyclotetradecane endowed with two Methylphosphonic Acid pendant arms in the 1 4 positions
Dalton Transactions, 2008Co-Authors: Jana Havlickova, Jan Kotek, Ivana Cisařova, Tomas Vitha, Hana Medova, Petr HermannAbstract:The title ligand, 1,4,8,11-tetraazacyclotetradecane-1,4-diyl-bis(Methylphosphonic Acid) (H4te2p1,4, H4L), was prepared by an optimized synthetic approach and its complexing properties towards selected metal ions were studied by means of potentiometry. The ligand forms a very stable complex with copper(II) (log β(CuL) = 27.21), with a high selectivity over binding of other metal ions (e.g. log β(ZnL) = 20.16, log β(NiL) = 21.92). The crystal structures of two intermediates in the ligand synthesis and two forms of the nickel(II) complex (obtained by crystallization at different pH) were determined. From Acid solution, the crystals of trans-O,O-[Ni(H3L)]Cl·H2O were isolated. In such complex species, one phosphonate pendant arm is double- and the second arm is monoprotonated. The isolation of such species demonstrates a high kinetic inertness of the complex. The central metal ion is surrounded by four in-plane nitrogen atoms (in the ring configuration III) and two oxygen atoms of pendant moieties in the apical positions of octahedral coordination sphere. From neutral solution, the crystals of {trans-O,O-[Ni(H2L)]}3·5H2O were isolated. The molecular structures of the complex units found in this structure are analogous to that found in trans-O,O-[Ni(H3L)]Cl·H2O.
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thermodynamic kinetic and solid state study of divalent metal complexes of 1 4 8 11 tetraazacyclotetradecane cyclam bearing two trans 1 8 Methylphosphonic Acid pendant arms
Dalton Transactions, 2006Co-Authors: Ivona Svobodova, Jan Kotek, Petr Hermann, Přemysl Lubal, Jana Havlickova, Jan Plutnar, Ivan LukesAbstract:Divalent metal complexes of macrocyclic ligand 1,4,8,11-tetraazacyclotetradecane-1,8-bis(Methylphosphonic Acid)) (1,8-H4te2p, H4L) were investigated in solution and in the solid state. The majority of transition-metal ions form thermodynamically very stable complexes as a consequence of high affinity for the nitrogen atoms of the ring. On the other hand, complexes with Mn2+, Pb2+ and alkaline earth ions interacting mainly with phosphonate oxygen atoms are much weaker than those of transition-metal ions and are formed only at higher pH. The same tendency is seen in the solid state. Zinc(II) ion in the octahedral trans-O,O-[Zn(H2L)] complex is fully encapsulated within the macrocycle (N4O2 coordination mode with protonated phosphonate oxygen atoms). The polymeric {[Pb(H2L)(H2O)2]·6H2O}n complex has double-protonated secondary amino groups and the central atom is bound only to the phosphonate oxygen atoms. The phosphonate moieties bridge lead atoms creating a 3D-polymeric network. The [{(H2O)5Mn}2(µ-H2L)](H2L)·21H2O complex contains two pentaaquamanganese(II) moieties bridged by a ligand molecule protonated on two nitrogen atoms. In the complex cation, oxygen atoms of the phosphonate groups on the opposite sites of the ring occupy one coordination site of each metal ion. The second ligand molecule is diprotonated and balances the positive charge of the complex cation. Complexation of zinc(II) and cadmium(II) by the ligand shows large differences in reactivity of differently protonated ligand species similarly to other cyclam-like complexes. Acid-assisted dissociations of metal(II) complexes occur predominantly through triprotonated species [M(H3L)]+ and take place at pH < 5 (Zn2+) and pH < 6 (Cd2+).
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selective protection of 1 4 8 11 tetraazacyclotetradecane cyclam in position 1 4 with the phosphonothioyl group and synthesis of a cyclam 1 4 bis Methylphosphonic Acid crystal structures of several cyclic phosphonothioamides
Collection of Czechoslovak Chemical Communications, 2006Co-Authors: Tomas Vitha, Jan Kotek, Petr Hermann, Ivana Cisařova, Jakub Rudovský, Vojtěch Kubicek, Ivan LukesAbstract:A new cyclam-based ligand, 1,4,8,11-tetraazacyclotetradecane-1,4-bis(Methylphosphonic Acid) (1,4-H4te2p), was synthesized. Cyclam was protected by the reaction with PhP(S)Cl2 to form exclusively five-membered cyclic phenylphosphonothioic diamide 2 in a moderate yield. The solid-state structures of 2 and several by-products were determined. Compound 2 was isolated as two stable conformers differing in a mutual position of benzene ring and sulfur atom with respect to the cyclam ring. Compound 2 was used for the synthesis of 1,4-dibenzylcyclam. However, the deprotection of the thiophosphoryl-protected bis(methylphosphonate diester) with aqueous HCl under non-optimized conditions led to a mixture of cyclam derivatives differently substituted with Methylphosphonic Acid groups. The crystal structures of the target product, 1,4-H4te2p, and also 1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetrakis(Methylphosphonic Acid) (H8tetp) were determined. A similar reaction with cyclen (1,4,7,10-tetraazacyclododecane) led only to hardly purifiable mixtures.
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application of dipon 1 4 8 11 tetraazacyclotetradecane 4 11 bis Methylphosphonic Acid as selective complexing agent for determination of copper ii
Journal of Inclusion Phenomena and Macrocyclic Chemistry, 2004Co-Authors: Ivona Svobodova, Jan Kotek, Petr Hermann, Přemysl Lubal, Josef HavelAbstract:A new macrocyclic ligand, 1,4,8,11-tetraazacyclotetradecane-1,8-bis(Methylphosphonic Acid)(dipon), is selective complexing agent for copper(II) over other transition metal ions. The ligand was tested for analytical applications of copper(II) determination. Spectrophotometric determination under optimal experimental conditions (−log [H+]= 5.5, cL≈ 5 × 10−4 mol L−1, λ= 310 nm) is valid in dynamic range (5–200)× 10−6 mol L−1 with detection limit 2.2 × 10−6 mol L−1, i.e. 0.14 μg ml−1. Volumetric determination of copper(II) with standardized dipon solution was used for copper(II) determination at micromolar concentration level without any necessity to sequester interfering metal ions. A sharp end point of titration was detected by UV/VIS spectrophotometry. Both methods were tested on artificial and real samples (spiked mineral water, alloys) and gave satisfactory results without any systematic error. The advantage of both methods is their simplicity, rapidity and no sensitivity to the presence of other metal ions.
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high thermodynamic stability and extraordinary kinetic inertness of copper ii complexes with 1 4 8 11 tetraazacyclotetradecane 1 8 bis Methylphosphonic Acid example of a rare isomerism between kinetically inert penta and hexacoordinated copper ii complexes
Chemistry: A European Journal, 2003Co-Authors: Jan Kotek, Petr Hermann, Ivan Lukes, Ivana Cisařova, Ivona Svobodova, Přemysl Lubal, Tomas Godula, Petr Taborský, Josef HavelAbstract:In an aqueous solution at room temperature, 1,4,8,11-tetraazacyclotetradecane-1,8-bis(Methylphosphonic Acid) (H4L1) and CuII form a pentacoordinated (pc) complex, pc-[Cu(L1)]2-, exhibiting conformation I of the cyclam ring. At high temperature, the complex isomerises to a hexacoordinated isomer, trans-O,O-[Cu(L1)]2-, with a trans-III[Note ] conformation of the cyclam ring. In pc-[Cu(L1)]2-, four ring nitrogen atoms and one phosphonate oxygen atom are arranged around CuII in a structure that is half-way between a trigonal bipyramid and a tetragonal pyramid, with one phosphonic Acid group uncoordinated. In the trans-O,O-[Cu(L1)]2- isomer, the nitrogen atoms form a plane and the phosphonic Acid groups are in a mutually trans configuration. A structurally very similar ligand, 4-methyl-1,4,8,11-tetraazacyclotetradecane-1,8-bis(methylphosph onic Acid) (H4L2), forms an analogous pentacoordinated complex, pc-[Cu(L2)]2-, at room temperature. However, the complex does not isomerise to the octahedral complex analogous to trans-O,O-[Cu(L1)]2-. Because of the high thermodynamic stability of pc-[Cu(L1)]2-, (log =25.40(4), 25 degrees of Celsius, I=0.1 mol dm-3 KNO3) and the formation of protonated species, CuII is fully complexed in Acidic solution (-log [H+] ~ 3). Acid-assisted decomplexation of both of the isomers of [Cu(H2L1)] takes place only after protonation of both uncoordinated oxygen atoms of each phosphonate moiety and at least one nitrogen atom of the cycle. The exceptional kinetic inertness of both isomers is illustrated by their half-lives 1/2=19.7 min for pc-[Cu(H2L1)] and about seven months for trans-O,O-[Cu(H2L1)] for decomplexation in 5 M HClO4 at 25 degrees of Celsius. The mechanism of formation of pc-[Cu(L1)]2- is similar to those observed for other macrocyclic complexes.
Remi Metivier - One of the best experts on this subject based on the ideXlab platform.
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friedel crafts type reaction of pyrene with diethyl 1 isothiocyanato alkylphosphonates efficient synthesis of highly fluorescent diethyl 1 pyrene 1 carboxamido alkylphosphonates and 1 pyrene 1 carboxamido Methylphosphonic Acid
Beilstein Journal of Organic Chemistry, 2015Co-Authors: Anna Wronapiotrowicz, Janusz Zakrzewski, Anna Gajda, Tadeusz Gajda, Anna Makal, Arnaud Brosseau, Remi MetivierAbstract:Friedel-Crafts-type reaction of pyrene with diethyl 1-(isothiocyanato)alkylphosphonates promoted by trifluoromethanosulfonic Acid afforded diethyl 1-(pyrene-1-carbothioamido)alkylphosphonates in 83-94% yield. These compounds were transformed, in 87-94% yield, into the corresponding diethyl 1-(pyrene-1-carboxamido)alkylphosphonates by treatment with Oxone(®). 1-(Pyrene-1-carboxamido)Methylphosphonic Acid was obtained in a 87% yield by treating the corresponding diethyl phosphonate with Me3Si-Br in methanol. All of the synthesized amidophosphonates were emissive in solution and in the solid state. The presence of a phosphonato group brought about an approximately two-fold increase in solution fluorescence quantum yield in comparison with that of a model N-alkyl pyrene-1-carboxamide. This effect was tentatively explained by stiffening of the amidophosphonate lateral chain which was caused by the interaction (intramolecular hydrogen bond) of phosphonate and amide groups. The synthesized phosphonic Acid was soluble in a biological aqueous buffer (PBS, 0.01 M, pH 7.35) and was strongly emissive under these conditions (λem = 383, 400 nm, τ = 18.7 ns, ΦF > 0.98). Solid-state emission of diethyl 1-(pyrene-1-carboxamido)methylphosphonate (λmax = 485 nm; ΦF = 0.25) was assigned to π-π aggregates, the presence of which was revealed by single-crystal X-ray diffraction analysis.
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Friedel–Crafts-type reaction of pyrene with diethyl 1-(isothiocyanato)alkylphosphonates. Efficient synthesis of highly fluorescent diethyl 1-(pyrene-1-carboxamido)alkylphosphonates and 1-(pyrene-1-carboxamido)Methylphosphonic Acid
Beilstein-Institut, 2015Co-Authors: Anna Wrona-piotrowicz, Janusz Zakrzewski, Anna Gajda, Tadeusz Gajda, Anna Makal, Arnaud Brosseau, Remi MetivierAbstract:Friedel–Crafts-type reaction of pyrene with diethyl 1-(isothiocyanato)alkylphosphonates promoted by trifluoromethanosulfonic Acid afforded diethyl 1-(pyrene-1-carbothioamido)alkylphosphonates in 83–94% yield. These compounds were transformed, in 87–94% yield, into the corresponding diethyl 1-(pyrene-1-carboxamido)alkylphosphonates by treatment with Oxone®. 1-(Pyrene-1-carboxamido)Methylphosphonic Acid was obtained in a 87% yield by treating the corresponding diethyl phosphonate with Me3Si-Br in methanol. All of the synthesized amidophosphonates were emissive in solution and in the solid state. The presence of a phosphonato group brought about an approximately two-fold increase in solution fluorescence quantum yield in comparison with that of a model N-alkyl pyrene-1-carboxamide. This effect was tentatively explained by stiffening of the amidophosphonate lateral chain which was caused by the interaction (intramolecular hydrogen bond) of phosphonate and amide groups. The synthesized phosphonic Acid was soluble in a biological aqueous buffer (PBS, 0.01 M, pH 7.35) and was strongly emissive under these conditions (λem = 383, 400 nm, τ = 18.7 ns, ΦF > 0.98). Solid-state emission of diethyl 1-(pyrene-1-carboxamido)methylphosphonate (λmax = 485 nm; ΦF = 0.25) was assigned to π–π aggregates, the presence of which was revealed by single-crystal X-ray diffraction analysis
Přemysl Lubal - One of the best experts on this subject based on the ideXlab platform.
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chemical and biological evaluation of 153sm and 166ho complexes of 1 4 7 10 tetraazacyclododecane 1 4 7 10 tetrakis Methylphosphonic Acid monoethylester h4dotpoet
Journal of Inorganic Biochemistry, 2008Co-Authors: Michaela Forsterova, Petr Hermann, Přemysl Lubal, Zuzana Jandurova, Fernanda Marques, Lurdes Gano, Jakub Vaněk, Isabel SantosAbstract:The novel Methylphosphonic Acid monoethylester (H4dotpOEt) has been synthesized and characterized and their complexes with Sm(III) and Ho(III) ions were studied. Dissociation constants of the ligand are lower than those of H4dota. The stability constants of the Ln(III)-H4dotpOEt complexes are surprisingly much lower that those of H4dota probably due to a lower coordination ability of the phosphonate monoester groups. Acid-assisted decomplexation studies have shown that both complexes are less kinetically inert than the H4dota complexes, but still much more inert than complexes of open-chain ligands. Nevertheless, the synthesis of 153Sm and 166Ho complexes with this ligand led to stable complexes both in vitro and in vivo. A very low binding of these complexes to hydroxyapatite (HA) and calcified tissues was observed confirming the assumption that a fully ionized phosphonate group(s) is necessary for a strong bone affinity. Both complexes show similar behaviour in vivo.
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thermodynamic kinetic and solid state study of divalent metal complexes of 1 4 8 11 tetraazacyclotetradecane cyclam bearing two trans 1 8 Methylphosphonic Acid pendant arms
Dalton Transactions, 2006Co-Authors: Ivona Svobodova, Jan Kotek, Petr Hermann, Přemysl Lubal, Jana Havlickova, Jan Plutnar, Ivan LukesAbstract:Divalent metal complexes of macrocyclic ligand 1,4,8,11-tetraazacyclotetradecane-1,8-bis(Methylphosphonic Acid)) (1,8-H4te2p, H4L) were investigated in solution and in the solid state. The majority of transition-metal ions form thermodynamically very stable complexes as a consequence of high affinity for the nitrogen atoms of the ring. On the other hand, complexes with Mn2+, Pb2+ and alkaline earth ions interacting mainly with phosphonate oxygen atoms are much weaker than those of transition-metal ions and are formed only at higher pH. The same tendency is seen in the solid state. Zinc(II) ion in the octahedral trans-O,O-[Zn(H2L)] complex is fully encapsulated within the macrocycle (N4O2 coordination mode with protonated phosphonate oxygen atoms). The polymeric {[Pb(H2L)(H2O)2]·6H2O}n complex has double-protonated secondary amino groups and the central atom is bound only to the phosphonate oxygen atoms. The phosphonate moieties bridge lead atoms creating a 3D-polymeric network. The [{(H2O)5Mn}2(µ-H2L)](H2L)·21H2O complex contains two pentaaquamanganese(II) moieties bridged by a ligand molecule protonated on two nitrogen atoms. In the complex cation, oxygen atoms of the phosphonate groups on the opposite sites of the ring occupy one coordination site of each metal ion. The second ligand molecule is diprotonated and balances the positive charge of the complex cation. Complexation of zinc(II) and cadmium(II) by the ligand shows large differences in reactivity of differently protonated ligand species similarly to other cyclam-like complexes. Acid-assisted dissociations of metal(II) complexes occur predominantly through triprotonated species [M(H3L)]+ and take place at pH < 5 (Zn2+) and pH < 6 (Cd2+).
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application of dipon 1 4 8 11 tetraazacyclotetradecane 4 11 bis Methylphosphonic Acid as selective complexing agent for determination of copper ii
Journal of Inclusion Phenomena and Macrocyclic Chemistry, 2004Co-Authors: Ivona Svobodova, Jan Kotek, Petr Hermann, Přemysl Lubal, Josef HavelAbstract:A new macrocyclic ligand, 1,4,8,11-tetraazacyclotetradecane-1,8-bis(Methylphosphonic Acid)(dipon), is selective complexing agent for copper(II) over other transition metal ions. The ligand was tested for analytical applications of copper(II) determination. Spectrophotometric determination under optimal experimental conditions (−log [H+]= 5.5, cL≈ 5 × 10−4 mol L−1, λ= 310 nm) is valid in dynamic range (5–200)× 10−6 mol L−1 with detection limit 2.2 × 10−6 mol L−1, i.e. 0.14 μg ml−1. Volumetric determination of copper(II) with standardized dipon solution was used for copper(II) determination at micromolar concentration level without any necessity to sequester interfering metal ions. A sharp end point of titration was detected by UV/VIS spectrophotometry. Both methods were tested on artificial and real samples (spiked mineral water, alloys) and gave satisfactory results without any systematic error. The advantage of both methods is their simplicity, rapidity and no sensitivity to the presence of other metal ions.
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high thermodynamic stability and extraordinary kinetic inertness of copper ii complexes with 1 4 8 11 tetraazacyclotetradecane 1 8 bis Methylphosphonic Acid example of a rare isomerism between kinetically inert penta and hexacoordinated copper ii complexes
Chemistry: A European Journal, 2003Co-Authors: Jan Kotek, Petr Hermann, Ivan Lukes, Ivana Cisařova, Ivona Svobodova, Přemysl Lubal, Tomas Godula, Petr Taborský, Josef HavelAbstract:In an aqueous solution at room temperature, 1,4,8,11-tetraazacyclotetradecane-1,8-bis(Methylphosphonic Acid) (H4L1) and CuII form a pentacoordinated (pc) complex, pc-[Cu(L1)]2-, exhibiting conformation I of the cyclam ring. At high temperature, the complex isomerises to a hexacoordinated isomer, trans-O,O-[Cu(L1)]2-, with a trans-III[Note ] conformation of the cyclam ring. In pc-[Cu(L1)]2-, four ring nitrogen atoms and one phosphonate oxygen atom are arranged around CuII in a structure that is half-way between a trigonal bipyramid and a tetragonal pyramid, with one phosphonic Acid group uncoordinated. In the trans-O,O-[Cu(L1)]2- isomer, the nitrogen atoms form a plane and the phosphonic Acid groups are in a mutually trans configuration. A structurally very similar ligand, 4-methyl-1,4,8,11-tetraazacyclotetradecane-1,8-bis(methylphosph onic Acid) (H4L2), forms an analogous pentacoordinated complex, pc-[Cu(L2)]2-, at room temperature. However, the complex does not isomerise to the octahedral complex analogous to trans-O,O-[Cu(L1)]2-. Because of the high thermodynamic stability of pc-[Cu(L1)]2-, (log =25.40(4), 25 degrees of Celsius, I=0.1 mol dm-3 KNO3) and the formation of protonated species, CuII is fully complexed in Acidic solution (-log [H+] ~ 3). Acid-assisted decomplexation of both of the isomers of [Cu(H2L1)] takes place only after protonation of both uncoordinated oxygen atoms of each phosphonate moiety and at least one nitrogen atom of the cycle. The exceptional kinetic inertness of both isomers is illustrated by their half-lives 1/2=19.7 min for pc-[Cu(H2L1)] and about seven months for trans-O,O-[Cu(H2L1)] for decomplexation in 5 M HClO4 at 25 degrees of Celsius. The mechanism of formation of pc-[Cu(L1)]2- is similar to those observed for other macrocyclic complexes.