Synthesis of bifunctional chelating agents based on mono and diphosphonic derivatives of diethylenetriaminepentaacetic acid

Bifunctional chelating agents (BFCAs) are small molecules containing a chelating unit, able to strongly coordinate a metal ion, and a reactive functional group, devised to form a stable covalent bond with another molecule. BFCAs are widely employed since their conjugation to a suitable biomolecule (e.g., a peptide or an antibody) allows the synthesis of diagnostic or therapeutic agents that specifically target diseased tissue with metals or radiometals. For this reason, BFCAs find application in diagnostic imaging, molecular imaging, and radiotherapy of cancer. The synthesis of new BFCAs based on a diethylenetriaminepentaacetic acid (DTPA) structure in which one or two carboxylic groups are replaced with phosphonic units is described. The phosphonic group, aside from being a classical isostere of the carboxylic acid in coordination chemistry, allows to modulate the physico-chemical properties of the ligands and of the corresponding complexes.     

Efficient and tunable synthesis of new polydentate bifunctional chelating agents using click chemistry

Two novel bifunctional chelating agents, which are bistriazole-based polyaminocarboxylic acids, have been designed and synthesised in high yields. An elegant synthetic approach using the Cu-catalysed azide-alkyne cycloaddition has been developed. This convenient route could be employed for the synthesis of a variety of polydentate bifunctional chelators.     

New chelating agents for colorimetric determination of calcium

Two new calcium chromoionophores2 and3 are described and their potential application to colorimetric determination of calcium is assessed. Chromogenic compound2 bears two acetic acid chelating groups and a 4-(4-nitrophenyl)azophenol chromophore. Its complexation of Ca²⁺ at pH 9.0 is accompanied by a 109-nm bathochromic shift and increase in the absorptivity. Triaryl chromoionophore3 bears two phosphonic acid chelating groups and the same azophenol chromophore. Compound3 exhibits a 107-nm bathochromic shift of the absorption maximum, an increase in the absorptivity upon complexation with Ca²⁺, and good selectivity for Ca²⁺ over Mg²⁺ at pH 7.0. Both chromoionophores exhibit linear responses from 0 to 4×10^–3 M Ca²⁺.     

Synthesis of a tetrazine-based catecholamide derivative and its evaluation as a chelating agent for removal of Cd(II), Co(II), and Cu(II)

The synthesis and structural characterization of a tetrazine-based catecholamide (CAM) ligand, N,N′-bis(N″-(aminoethyl)-2,3-bis(hydroxy)benzamide)-1,2,4,5-tetrazine-3,6-diamine (5), were investigated. All compounds were characterized by ¹H NMR spectroscopy, ¹³C NMR spectroscopy, and FTIR spectroscopy. The protonation equilibria of 5 and complexation capacities (log β_pqr) of Cd²⁺, Co²⁺, and Cu²⁺ complexes of 5 were evaluated through potentiometric titration and spectrophotometric titration, respectively. Species independent pM value (=?log [M]_free) was used to compare metal affinities with the final sequence Cu²⁺ > Cd²⁺ > Co²⁺. Results show that 5 has potential for heavy metal removal.     

Electrosynthesis of a new selective chelating agent for solid phase extraction of Ni(II) from water samples: characterisation and analytical applications

A new polymer as a selective chelating agent for separation and preconcentration of nickel ions from water samples was prepared by electropolymerisation of 4-nitrophenol. Electrosynthesis was carried out on the lead cathode in aqueous sodium acetate solution. The electrode-product is a dark-brown powder, insoluble in water but soluble in methanol, N,N-dimethylformamide (DMF) and tetrahydrofuran (THF). The electrode-product was characterised by differential scanning calorimetry (DSC), gel permeation chromatography (GPC), FT-IR, ¹H-NMR, cyclic voltammetry (CV) and UV-Vis spectrometry. A proper mechanism and structure of the prepared polymer was suggested. A few drops of methanolic solution of electrode-product formed a blue complex with nickel ions in an aqueous medium in the pH range of 6 to 10. This new chelating reagent was used as a coating material on activated charcoal and applied for solid phase extraction of trace amounts of nickel ions from natural and waste waters. The effect of different parameters such as type of eluent, elution conditions, sample volume and sample flow rate and mass of coating material were studied. In the presence of co-existing ions, no significant interferences were observed. Under the optimal conditions, limits of detection (LOD) and quantification (LOQ) were 0.32 and 1 µg L^?1 Ni(II), respectively. The proposed method was used for determination of Ni(II) in some lagoons south of the Caspian Sea and waste waters of factories. The validity of this method was confirmed by the comparison of the obtained results with the results of ICP-OES.     

Design and synthesis of new ethylenediamine or propylenediamine diacetic acid derivatives for Re(I) organometallic chemistry

A general synthetic approach for a novel range of bifunctional chelating agent (BCA) for the ‘fac-[M(CO)₃]⁺‘ core (M=^99mTc, ⁹⁹Tc or Re) has been developed. The strategy includes the facile preparation of these tridentate ligands possessing a tertiary amine bearing two carboxylic acid functions as coordinating site and an aromatic amino group for coupling to a biovector. First complexation study has shown that these compounds act exclusively as tridentate ligands (via the two acids and the tertiary amine functions). The convenient synthesis of these new ligands coupled with their high affinity for Re(I) make them quite promising for biomedical applications.     

含羟肟酸侧基高分子重金属捕集剂处理含铅废水的研究

铅是有毒的重金属,其污染主要来源于颜料、铅蓄电池、矿冶、电镀及印刷电路版制作等作业.铅在人和动植物中具有蓄积稳定性,进入人体后很难排除;停留体内对人的中枢神经系统和骨骼造成伤害,早已引起医学界重视,被列为严格控制排放的第一类污染物.     

Synthesis, polymerization and Cu complexation studies of a new styrene derivative of 2-hydroxyacetophenone

A new 5-vinyl-2-hydroxyacetophenone monomer was synthesized using Heck reaction. The monomer was obtained by reacting 5-bromo-2-hydroxyacetophenone with ethylene in a palladium catalyzed reaction. Better yield was obtained at low concentration of the catalyst, high temperature and pressure of the ethylene gas. The monomer was homopolymerized and copolymerized with styrene using free radical solution polymerization techniques and investigated for reactivity ratio, retardation effect of the monomer on the polymerization of styrene. Homopolymer with average molecular weight of 40,391 was found to form binuclear complex with Cu²⁺. The complex was evident from shift in n-π^* transition from 332-378 nm in UV region and appearance of strong absorption at 1578 cm⁻¹ in the IR of the precipitated complex.     

Two novel polymorphic forms of iron‐chelating agent deferiprone

Thalassemia is a genetic blood disorder requiring life‐long blood transfusions. This process often results in iron overload and can be treated by an iron‐chelating agent, like deferiprone (3‐hydroxy‐1,2‐dimethylpyridin‐4‐one), C₇H₉NO₂, in an oral formulation. The first crystal structure of deferiprone, (Ia), was reported in 1988 [Nelson et al. (1988). Can. J. Chem. 66 , 123–131]. In the present study, two novel polymorphic forms, (Ib) and (Ic), of deferiprone were identified concomitantly with polymorph (Ia) during the crystallization experiments. Polymorph (Ia) was redetermined at low temperature for comparison of the structural features and lattice energy values with polymorphs (Ib) and (Ic). Polymorph (Ia) crystallized in the orthorhombic space group Pbca, whereas both polymorphs (Ib) and (Ic) crystallized in the monoclinic space group P2₁/c. The asymmetric units of (Ia) and (Ib) contain one deferiprone molecule, while polymorph (Ic) has three crystallographically independent molecules (A, B and C). All three polymorphs have similar hydrogen‐bonding features, such as an R₂²(10) dimer formed by O—H…O hydrogen bonds, an R₄³(20) tetramer formed by C—H…O hydrogen bonds and π–π interactions, but the polymorphs differ in their molecular arrangements in the solid state and are classified as packing polymorphs. O—H…O and C—H…O hydrogen bonds lead to the formation of two‐dimensional hydrogen‐bonded parallel sheets which are interlinked by π–π stacking interactions. In the three‐dimensional crystal packing, the deferiprone molecules were aggregated as corrugated sheets in polymorphs (Ia) and (Ic), whereas in polymorph (Ib), they were aggregated as a square‐grid network. The characteristic crystalline peaks of polymorphs (Ia), (Ib) and (Ic) were established through powder X‐ray diffraction analysis. The Rietveld analysis was also performed to estimate the contribution of the polymorphs to the bulk material.     

MHNAMT,a new locating and chelating agent in thin-layer chromatographic determination of Cu(II), Co(II), Ni(II), Pd(II), Pt(IV), and Rh(III)

Summary Synthesis of MHNAMT [3-methyl-4-(2-hydroxy-1 naphthalideneamino)-5-mercapto-1,2,4-triazole] and its IR and NMR spectral data are reported. The high stability of the characteristically coloured chelates with Cu(II), Co(II), Ni(II), Pd(II), Pt(IV) and Rh(III) has been made the basis for their efficient ascending TLC separations on silica gel G layers, when present together. Results of three different solvent systems are included to assess efficient resolution of the chelates.     

Synthesis and properties of a temperature-sensitive chelating hydrogel and its metal complexes

A temperature-sensitive chelating hydrogel was synthesized by the copolymerization of 1-(β-acrylamidoethyl)-3-hydroxy-2-methyl-4(1H)-pyridinone (AHMP) and N-isopropylacrylamide (NIPAA) in the presence of N,N' -ethylene-bis-acrylamide as a crosslinking agent. The AHMP-NIPAA hydrogel formed a red complex with iron(III) and a pale green complex with Cu(II), respectively. It was observed that the hydrogel and its metal complexes had a high swelling ratio below the temperature of 35°C, while above that temperature the swelling ratios were dramatically decreased. Furthermore, the swelling ratio of the metal complexes was much lower at the swelling temperature (below 35°C) than that of the hydrogel itself, which might be due to the lower flexibility of the complexes. The iron(III) chelating study showed that the hydrogel had a high chelating efficiency at its swelling temperature, while the chelating efficiency of the hydrogel was very low at its deswelling temperature (>35°C). It was found that the chelating efficiency depended on the swelling ratio of the hydrogel in water, which could be explained by the difference in contactable internal surfaces at different temperatures. The hydrogel and its metal complexes could be easily separated at their deswelling temperature. It was also convenient to regenerate the hydrogel with 1 M HCl for reuse.     

Synthesis of nano-pore samarium (III)-imprinted polymer for preconcentrative separation of samarium ions from other lanthanide ions via solid phase extraction

A batch process was developed to separate samarium ions from some lanthanide ions by a novel solid phase which was prepared via the ion-imprinting technique. The samarium (III) ion-imprinted polymer (IIP) particles were synthesized by preparing the ternary complex of samarium ions with 5,7-dichloroquinoline-8-ol (DCQ) and 4-vinylpyridine (VP). Then, thermally copolymerization with styrene (functional monomer, STY) and divinylbenzene (cross-linking monomer, DVB) followed in the presence of 2-methoxy ethanol (porogen) and 2,2′-azobisisobutyronitrile (initiator, AIBN). The imprinted ion was removed by stirring the above particles with 50% (v/v) HCl to obtain the leached IIP particles. Moreover, control polymer (CP) particles were similarly prepared without the samarium ions. The unleached and leached IIP particles were characterized by X-ray diffraction (XRD), infra-red spectroscopy (IR), thermo gravimetric analysis (TGA) and scanning electron microscopy (SEM). Finally, preconcentration and selectivity studies for samarium and the other lanthanide ions were carried out. The preconcentration of the samarium (III) traces was studied during rebinding with the leached IIP particles as a function of pH, the weight of the polymer material, the preconcentration and the elution times, the eluent volume and the aqueous phase volume. These studies indicated that the samarium (III) amount as low as 1 μg, present in 200 mL, could be preconcentrated into 25 mL of 1.0 M HCl.     

Synthesis of thiol chelating resins and their adsorption properties toward heavy metal ions

A series of chelating resins, derived from a macroreticular styrene-divinylbenzene (2%) copolymer beads grafted with various poly(ethylene glycols) HO? (? CH₂? CH₂? O? )_n? H(n = 0, 4, 9, 13) and containing thiol groups as chelating functions, have been synthesized in a three-step reaction sequence. The structure of the functionalized resins was confirmed by IR spectrophotometry, elemental analysis, and differential scanning calorimetry. The complexation behavior of these thiol resins was investigated towards Hg(II), Cu(II), and Pb(II) ions in aqueous solution by a batch equilibration technique. The influence of pH on adsorption capacity was also examined. The adsorption values for metal ions' intake followed the order Hg(II) > Cu(II) > Pb(II). The affinity of these polymers towards Hg(II) ions was so high that the total mercury level in the liquid decreased from 20 ppm to below 10 ppb after 2 h of treatment. Polymers can be regenerated by washing with a solution of hydrochloric acid (6N) and 10% by weight of an aqueous solution of thiourea. © 1994 John Wiley & Sons, Inc.     

Synthesis of 2-aminomethyl-1,10-phenanthroline. A new chelating agent and versatile synthon for other chelating compounds

The synthesis of 2-aminomethyl-1,10-phenanthroline ( 4 ) from 1,10-phenanthroline ( 1 ) is described. The reduction of 2-cyano-1,10-phenanthroline ( 3 ) to 4 in the presence of 10% palladium on carbon in acetic acid under mild reaction conditions also proved to be a very efficient method for conversion of cyanopyridines to methylaminopyridines.     

Synthesis and complexation properties towards metal ions of new tri-substituted thiacalix[4]arenes

New thiacalix[4]arenes appended with three amide functions have been prepared. Their conformations have been solved thanks to ¹H NMR 2D correlation spectroscopy (COSY) and nuclear overhauser and exchange spectroscopy (NOESY). The complexation ability of these ligands towards various metal ions (Cd^2 + , Pb^2 + , Pd^2 + , Ni^2 + , Hg^2 + , Hg⁺, Ag⁺, Zn^2 +  and Cu^2 + ) has been investigated by the UV–vis absorption and the stoichiometry of the metal–ligand complexes was determined.     

Synthesis of two new crown ethers containing selenium and the complexation of one of them with silver and lead

Two new macrocyclic crown ethers containing one or two selenium donor atoms have been prepared. Diselena-18-crown-6 (2) was found to transport silver ions through a methylene chloride bulk membrane at about the same rate as the analogous dithia- (3) and diaza-18-crown-6 (4) compounds and transported lead ions about the same as dithia-18-crown-6 but better than diaza-18-crown-6.     

新的偶氮酚型和酚兰型生色开链冠醚的合成和配位性质

用酚型开链冠醚1a和1b为原料, 在碱溶液中合成了两类生色开链冠醚: 一类是与对硝基苯重氮氟硼酸盐反应生成的偶氮酚型(2b和2b); 另一类是与N, N-二甲基对苯二胺和K~3[Fe(CN)~6]反应生成的酚兰型(3a和3b)。用紫外-可见光谱法研究了这些生色开链冠醚与碱金属和碱土金属离子的配位性质。发现在THF-H~2O中, 2a对LiClO~4和Ca(ClO~4)~2, 2b对LiClO~4、NaClO~4和Ca(ClO~4)~2, 有较显著的选择性变色作用; 而3a和3b在CH~3CN中, 则对LiClO~4、NaClO~4和各种碱土金属盐,均有不同程度的变色作用, 尤其以对Ca^2^+和Sr^2^+作用时的△λ~m~a~x为最大。这些结果表明, 2a和2b的配位性质分别与由邻苯二酚衍生的2'a和2'b相似, 而3a和3b的配位性质则分别与由邻苯二酚衍生的3'b相似。     

一种三元共聚物磷酸盐的合成及性能研究

由丙烯酰胺、丙烯酸、3-二甲胺基烯丙基磷酸在过硫酸铵-亚硫酸氢钠氧化还原引发体系下合成了一种新型的AM/AA/DMAAPA三元共聚物.确立了最佳反应条件:AM/AA= 3/1(wt％),引发剂用量0.5wt％,pH为7,反应温度为40℃;并通过红外光谱分析确认了AM/AA/DMAAPA三元共聚物结构.当Na+;Cab,...     

螯合剂对Co-Mo/Al_2O_3成型加氢脱硫催化剂性能的影响

以拟薄水铝石为原料,添加有机溶剂,经挤条成型、干煅、焙烧制备了比表面积大、孔分布宽的柱状γ-Al2O3载体;采用共浸渍法制备了系列Co-Mo/Al2O3催化剂(CoO和MoO3质量分数分别为2%和8%)。利用低温氮吸附、XRD和H2-TPR技术对催化剂进行了表征,考察了螯合剂柠檬酸(CA)、草酸(OA)和乙二胺四乙酸(EDTA)对成型催化剂粗苯加氢脱硫活性的影响。结果表明,添加螯合剂后,催化剂的前驱体主要沉积在载体的3~10 nm中孔内,活性组分以无定形态高度分散在载体上。添加CA可提高催化剂的还原性,显著降低Mo6+的还原温度。在300℃、3.0 MPa、液体空速(LHSV)为2 h-1和氢油体积比为600的条件下,噻吩硫的脱除率可达到99.9%以上。