A new chelating sorbent for metal ion extraction under high saline conditions

A new chelating polymeric sorbent was developed by functionalizing Amberlite XAD-16 with 1,3-dimethyl-3-aminopropan-1-ol via a simple condensation mechanism. The newly developed chelating matrix offered a high resin capacity and faster sorption kinetics for the metal ions such as Mn(II), Pb(II), Ni(II), Co(II), Cu(II), Cd(II) and Zn(II). Various physio-chemical parameters like pH-effect, kinetics, eluant volume and flow rate, sample breakthrough volume, matrix interference effect on the metal ion sorption have been studied. The optimum pH range for the sorption of the above mentioned metal ions were 6.0–7.5, 6.0–7.0, 8.0–8.5, 7.0–7.5, 6.5–7.5, 7.5–8.5 and 6.5–7.0, respectively. The resin capacities for Mn(II), Pb(II), Ni(II), Co(II), Cu(II), Cd(II) and Zn(II) were found to be 0.62, 0.23, 0.55, 0.27, 0.46, 0.21 and 0.25 mmol g⁻¹ of the resin, respectively. The lower limit of detection was 10 ng ml⁻¹ for Cd(II), 40 ng ml⁻¹ for Mn(II) and Zn(II), 32 ng ml⁻¹ for Ni(II), 25 ng ml⁻¹ for Cu(II) and Co(II) and 20 ng ml⁻¹ for Pb(II). A high preconcentration value of 300 in the case of Mn(II), Co(II), Ni(II), Cu(II),Cd(II) and a value of 500 and 250 for Pb(II) and Zn(II), respectively, were achieved. A recovery of >98% was obtained for all the metal ions with 4 M HCl as eluting agent except in the case of Cu(II) where in 6 M HCl was necessary. The chelating polymer showed low sorption behavior to alkali and alkaline earth metals and also to various inorganic anionic species present in saline matrix. The method was applied for metal ion determination from water samples like seawater, well water and tap water and also from green leafy vegetable, from certified multivitamin tablets and steel samples.     

Synthesis,spectral, structural characterization and biological activity of new palladium(II) complexes containing 3‐acetyl‐8‐methoxy‐2H‐chromen‐2‐one derived Schiff bases

Four different mononuclear palladium(II) complexes of 3‐acetyl‐8‐methoxycoumarin Schiff bases were synthesized and characterized by spectrochemical techniques. Further analysis through X‐ray crystallography confirmed the structures of the complexes. Their interactive ability with Calf Thymus DNA and protein (Bovine Serum Albumin and Human Serum Albumin) were investigated by means of absorption and emission methods. The intercalative mode of binding with DNA was supported by EB displacement studies and viscosity measurements. Configurational changes that occurred in the proteins have been analysed with the help of 3D fluorescence studies. The complexes were shown to have good antimicrobial activity against the tested bacterial and fungal pathogens. In addition, antiproliferative activity of the complexes was evaluated on A549 and MCF‐7 cell lines and the complexes were comparatively more active than the standard drug cisplatin. Among the compounds, complex 3 was the most effective against MCF‐7 (IC₅₀ value of 5.20 ± 0.15 μM) and A549 (5.09 ± 0.13 μM) compared with the other complexes 1 (6.48 ± 0.17 μM; 5.98 ± 0.09 μM), 2 (5.53 ± 0.12 μM; 5.85 ± 0.11 μM), 4 (6.73 ± 0.19 μM; 6.63 ± 0.16 μM) and cisplatin (16.79 ± 0.08 μM; 15.10 ± 0.05 μM) respectively. LDH and NO release assays confirmed the cytotoxic potential of the synthesized complexes.     

Synthesis,spectral, electrochemical and catalytic studies of new Ru(III) tetradentate Schiff base complexes

The synthesis and characterization of several hexa‐coordinated ruthenium(III) Schiff base complexes of the type [RuX(EPh₃)(L)] (X = Cl or Br; E = P or As; L = dianion of the tetradentate Schiff base) are reported. IR, EPR, electronic spectra and cyclic voltammetric data of the complexes are discussed. An octahedral geometry has been tentatively proposed for all of these complexes. The new complexes have been subjected to catalytic activity in the reaction of oxidation of alcohols in the presence of N‐methylmorpholine‐N‐oxide. Copyright © 2007 John Wiley & Sons, Ltd.     

Synthesis of Novel Receptors From 7-Deoxycholic Acid and Studies on Their Cation Binding Properties

The synthesis and cation binding properties of chiral crown ethers derived from 7-deoxycholic acid along with their application in asymmetric Michael reaction are described.     

Palladium(II) complexes of Schiff bases derived from 5-amino-2,4-(1H, 3H)pyrimidinedione (5-aminouracil) and 1,2-dihydro-1,5-dimethyl-2-phenyl-4-amino-3H-pyrazol-3-one

Summary New palladium(II) complexes of Schiff bases, obtained from 5-aminouracil, (AUH), and acetylacetone (AUAcAcH₂), benzaldehyde (AUBALH), furan-2-aldehyde (AUFALH), 2-hydroxynaphthaldehyde (AUNALH₂), pyridine-2-aldehyde (AUPyALH) or salicylaldehyde (AUSALH₂) and from 1,2-dihydro-1,5-dimethyl-2-phenyl-4-amino-3H-pyrazol-3-one (AAPy) and acetylacetone (AAPyAcAcH), 2-hydroxyacetophenone (AAPyAPH), furan-2-aldehyde (AAPyFAL), pytidine-2-aldehyde (AAPyPyAL), or salicylaldehyde (AAPySALH), have been prepared. The complexes, with formulae PdL₂Cl₂ (L=AUBALH, AUFALH or AUSALH₂); PdLCl₂ (L=AUAcAcH₂, AUNALH₂, AUPyALH, AAPyFAL or AAPyPyAL) and PdLCl (L=AAPyAcAc or AAPySAL) were characterized by elemental analysis, i.r. and electronic spectral studies, thermogravimetric analyses and magnetic and conductance measurements. The x-ray powder diffraction pattern of one of the complexes was also examined. The complexes were screened for their possible antitumour activityin vitro.     

Enhanced metal extractive behavior using dual mechanism bifunctional polymer: an effective metal chelatogen

A new class of chelating polymers using Amberlite XAD-16 (AXAD-16) modified with (N-(3,4-dihydroxy)benzyl)-4-amino,3-hydroxynapthalene-1-sulphonic acid has been developed based on dual mechanism bifunctional polymers, for the extraction of transition and post-transition metal ions. The optimum pH conditions for the quantitative sorption of metal ions were studied. The developed method showed superior extraction qualities with high metal loading capacities of 71, 85, 182, 130 and 46 mg g⁻¹ for Ni(II), Cd(II), Pb(II), Cu(II) and Co(II), respectively. The rate of metal ion uptake i.e. kinetics studies performed under optimum levels showed a time duration of <5 min except for Co(II) which required 20 min, for complete metal ion saturation. Desorption of metal ions were effective with 15 ml of 2 M HCl/HNO₃ prior to detection using flame atomic absorption spectrophotometer. The chelating polymer was highly ion-selective in nature even in the presence of large concentrations of alkali and alkaline earth metal ions, with a high preconcentrating ability for the metal ions of interest. The developed chelating matrix was tested on its utility with synthetic and real samples like river/sea/tap/well water samples and also with multivitamin/mineral tablets, showed R.S.D. values of <2.5% reflecting on the accuracy and reproducibility of data using the newly developed resin matrix.     

A column system for the selective extraction of U(VI) and Th(IV) using a new chelating sorbent

A new method has been developed using (bis-3,4-dihydroxy benzyl)p-phenylene diamine functionalized to XAD-16 (a polystyrene divinyl benzene copolymer) matrix, to preconcentrate mainly U(VI) and Th(IV) from synthetic and real samples. The developed method is free from matrix interference due to alkali and alkaline metal ions and preconcentrates the actinides with a high degree of selectivity, with consistent trace recoveries. The new chelating resin provides dramatic improvement in metal exchange rate, with half value saturation time (t_1/2) of less than 1.6 min. The developed method was superior in its metal loading capacity for U(VI) and Th(IV), with values of 0.666 and 0.664 mmol g⁻¹, respectively. Various physio-chemical properties like effect of solution pH, kinetic studies, resin loading capacity, sample breakthrough volume, matrix effects etc., on metal ion sorption to sorbent phase, were studied using both batch and column method. The new chelatogen was applied to extract U(VI) from near neutral real water samples. Preconcentration and separation of metal ions were possible through pH variation and also by varying the eluant concentration. A high preconcentration factor value of 350 with a lower limit of detection of 20 and 30 ng cm⁻³ was obtained for U(VI) and Th(IV), respectively. The practical applicability of the developed resin was examined using synthetic and real samples such as sea/well water samples. The method provides low relative standard deviation values of <3.5% for all analytical measurements, reflecting on the reproducibility and accuracy of the developed method. The new resin is quite durable with recycling time >35 cycles, without any major change in its quantitative metal uptake nature.     

Preparation,spectral characterization,electrochemistry, EXAFS,antibacterial and catalytic activity of new ruthenium (III) complexes containing ONS donor ligands with triphenylphosphine/arsine

New hexa‐coordinated ruthenium (III) complexes of the type [RuX(EPh₃)₂(L)] (X = Cl or Br; L = dibasic tridentate Schiff base ligand; E = P or As) have been synthesized by the reactions of [RuCl₃(PPh₃)₃], [RuCl₃(AsPh₃)₃] or [RuBr₃(AsPh₃)₃] with the appropriate Schiff base ligands derived by the condensation of salicylaldehyde and 2‐hydroxy‐1‐naphthaldehyde with N(4) substituted thiosemicarbazones. All the new complexes were characterized using various physico‐chemical methods such as elemental analyses, infrared, electron paramagnetic resonance (EPR) spectroscopy, magnetic moment and cyclic voltammetry. Based on the extended X‐ray absorption fine structure (EXAFS) analysis, an octahedral structure has been confirmed for the complexes. The new complexes have been subjected to the catalytic activity and antibacterial studies. Copyright © 2005 John Wiley & Sons, Ltd.     

Synthesis,spectral characterization,electrochemistry and catalytic activities of Cu(II) complexes of bifunctional tridentate Schiff bases containing O?N?O donors

Paramagnetic copper(II) complexes of the type [Cu(PPh₃)(L)] (where L = bifunctional tridentate Schiff bases) were synthesized from the reaction of anthranillic acid with salicylaldehyde (H₂L¹), 2‐hydroxy‐1‐naphthaldehyde (H₂L²), o‐hydroxyacetophenone (H₂L³) and o‐vanillin (H₂L⁴) with monomeric metal precursor [CuCl₂(PPh₃)₂]. The obtained complexes were characterized by elemental analysis, magnetic susceptility and spectroscopic methods (FT‐IR, UV–vis and EPR and cyclic voltammetry). EPR and redox potential studies have been carried out to elucidate the electronic structure, nature of metal–ligand bonding and electrochemical features. EPR spectra exhibit a four line pattern with nitrogen super‐hyperfine couplings originating from imine nitrogen atom. These planar complexes possess a significant amount of tetrahedral distortion leading to a pseudo‐square planar geometry, as is evidenced from EPR properties. Cyclic voltammograms of all the complexes display quasireversible oxidations, Cu(III)? Cu(II), in the range 0.31–0.45 V and reduction peaks, Cu(II)? Cu(I),in the range ?0.29 to ?0.36 V, involving a large geometrical change and irreversible. The observed redox potentials vary with respect to the size of the chelate ring of the Schiff base ligands. Further, the catalytic activity of all the complexes has been found to be high towards the oxidation of alcohols into aldehydes and ketones in the presence of N‐methylmorpholine‐N‐oxide as co‐oxidant. The formation of high valent Cu^IV?O oxo species as a catalytic intermediate is proposed for the catalytic process. Copyright © 2008 John Wiley & Sons, Ltd.