Synthesis,structural studies and biological activity of dioxomolybdenum(VI), dioxotungsten(VI), thorium(IV) and dioxouranium(VI) complexes with 2-hydroxy-5-methyl and 2-hydroxy-5-chloroacetophenone benzoylhydrazone

New complexes of MoO₂(VI), WO₂(VI), Th(IV) and UO₂(VI) with aroyl hydrazones have been prepared and characterized by various physicochemical methods. Elemental analysis suggested 1 : 1 metal : ligand stoichiometry for MoO₂(VI), WO₂(VI), and UO₂(VI) complexes whereas 1 : 2 for Th(VI) complexes. The physicochemical studies showed that MoO₂(VI), Th(IV) and UO₂(VI) complexes are octahedral. The electrical conductivity of these complexes lies in the range 1.00 × 10⁻⁷−3.37 × 10⁻¹¹Ω⁻¹ cm⁻¹ at 373 K. The complexes were found to be quite stable and decomposition of the complexes ended with respective metal oxide as a final product. The thermal dehydration and decomposition of these complexes were studied kinetically using both Coats-Redfern and Horowitz-Metzger methods. It was found that the thermal decomposition of the complexes follow first order kinetics. The thermodynamic parameters of the decomposition are also reported. The biological activities of ligands and their metal complexes were tested against various microorganisms.     

Ligational behavior of thiosemicarbazone,semicarbazone and thiocarbohydrazone ligands towards VO(IV), Ce(III), Th(IV) and UO2(VI) ions: Synthesis,structural characterization and biological studies

Mono- and binuclear VO(IV), Ce(III), Th(IV) and UO₂(VI) complexes of thiosemicarbazone, semicarbazone and thiocarbohydrazone ligands derived from 4,6-diacetylresorcinol were synthesized. The structures of these complexes were elucidated by elemental analyses, IR, UV–vis, ESR, ¹H NMR and mass spectra as well as conductivity and magnetic susceptibility measurements and thermal analyses. The thiosemicarbazone (H₄L¹) and the semicarbazone (H₄L²) ligands behave as dibasic pentadentate ligands in case of VO(IV) and UO₂(VI) complexes, tribasic pentadentate in case of Ce(III) complexes and monobasic pentadentate in case of Th(IV) complexes. However, the thiocarbohydrazone ligand (H₃L³) acts as a monobasic tridentate ligand in all complexes except the VO(IV) complex in which it acts as a dibasic tridentate ligand. The antibacterial and antifungal activities were also tested against Rhizobium bacteria and Fusarium-Oxysporium fungus. The metal complexes of H₄L¹ ligand showed a higher antibacterial effect than the free ligand while the other ligands (H₄L² and H₃L³) showed a higher effect than their metal complexes. The antifungal effect of all metal complexes is lower than the free ligands.     

Zirconium (IV), Thorium (IV) and Dioxouranium (VI) Complexes of Dibasic Tridentate Schiff Bases

Dibasic tridentate Schiff bases obtained by the condensation of O -aminobenzoic acid with salicyldehyde and its 5-chloro and 5-bromo derivatives were synthesised and used to pracipitate Zr(IV), Th(IV) and UO₂(VI) metals as complexes. The 1:1 (metal-ligand) stoichiometry of these complexes is shown by elemental analysis, gravimetric estimations and conductometric titrations while the structures of the complexes are proved by i.r. spectra and thermogravimetric analysis. The magnetic susceptibility measurements by Gouy method show, these complexes to be monormeic and diamagnetic. The molar conductance values in nitrobenzene indicate the nonelectrolytic behaviour of the complexes. The results show that the complexes of the type Zr(OH)²L.H²O, Th(OH)²L.H²O and UO²L.H²O are formed having solvent molecule in co-ordination with metal ion.     

Extraction of U(VI) and Th(IV) from nitric acid medium using tri(butoxyethyl) phosphate (TBEP) in <Emphasis Type="Italic">n</Emphasis>-paraffin

Extraction behavior of U(VI) and Th(IV) from nitric acid medium is investigated using organo-phosphorous extractant, tri(butoxyethyl) phosphate in n-paraffin at room temperature (27 ± 1 °C). The effect of diluents, nitric acid concentration as well as extractant concentration on extraction of U(VI) and Th(IV) are evaluated. Extraction of U(VI) and Th(IV) from nitric acid medium proceeds via solvation mechanism. Slope analysis technique showed the formation of neutral complexes of the type of UO₂(NO₃)₂·2TBEP and Th(NO₃)₄·3TBEP with U(VI) and Th(IV) respectively in the organic phase. The FTIR data showed shifting of P=O stretching frequency from 1,282 to 1,217 cm⁻¹ indicating the strong complexation of P=O group with UO₂ ²⁺ ions in the organic phase. Effect of stripping agents, other metal ions and their separation with respect to U(VI) extraction has also been investigated.     

Thermoanalytical studies of oxovanadium(IV)hydroxamate complexes

The thermal decomposition behavior of oxovanadium(IV)hydroxamate complexes of composition [VO(acac)(C₆H₅C(O)NHO)] (I), [VO(C₆H₅C(O)NHO)₂] (II), [VO(acac)(4-ClC₆H₄C(O)NHO)] (III), [VO(4-ClC₆H₄C(O)NHO)₂] (IV) (where acac = (CH₃COCHCOCH₃ ^–) synthesized from the reactions of VO(acac)₂ with equi- and bimolar amounts of potassium benzohydroxamate and potassium 4-chlorobenzohydroxamate in THF + MeOH solvent medium has been studied by TG and DTA techniques. TG curves indicated that complexes I, II, and IV undergo decomposition in single step to yield VO₂ as the final residue, while complex III decomposes in two steps to yield VO(acac) as the likely intermediate and VO₂ as the ultimate product of decomposition. The formation of VO₂ has been authenticated by IR and XRD studies. From the initial decomposition temperatures, the order of thermal stability for the complexes has been inferred as IV > I > III > II.     

Zirconium(IV) Thorium(IV) and Dioxouranium(VI) Complexes of Salicylidene o-Aminobenzothiol

Salicylidene-o-aminobenzothiol and its 5-chloro and 5-bromo derivatives, dibasic tridentate Schiff bases, dervied from the condensation of o-aminothiol and Salicylaldehyde, 5-chloro salicylaldehyde and 5-bromo salicylaldehyde, were used for coordination with Zr(IV), Th(IV) and UO₂(VI) metal inos. The I:I (metal-ligand) stoichiometry of these complexes is shown by elemental analysis and conductometric titrations. Molecular structure of these complexes are proved by Infra-red spectroscopy and thermogravimetric analysis. Magnetic susceptibility measurements of Zr(IV), Th(IV) and UO₂(VI) complexes show their diamagnetic and octahedral geometry. Results show that all the complexes have solvent molecules in coordination with metal ion.     

Zirconium (IV), Thorium (IV) and Dioxouranium (VI) Complexes of Dibasic Tridentate Schiff Bases

Dibasic tridentate Schiff bases obtained by the condensation of O -aminobenzoic acid with salicyldehyde and its 5-chloro and 5-bromo derivatives were synthesised and used to pracipitate Zr(IV), Th(IV) and UO₂(VI) metals as complexes. The 1: 1 (metal-ligand) stoichiometry of these complexes is shown by elemental analysis, gravimetric estimations and conductometric titrations while the structures of the complexes are proved by i.r. spectra and thermogravimetric analysis. The magnetic susceptibility measurements by Gouy method show, these complexes to be monormeic and diamagnetic. The molar conductance values in nitrobenzene indicate the nonelectrolytic behaviour of the complexes. The results show that the complexes of the type Zr(OH)₃L.H₂O₂ Th(OH)₂ L.H₂O and UO₂L.H₂O are formed having solvent molecule in co-ordination with metal ion.     

New Transition and Actinide Metal Complexes of 2‐Carboxy‐phenylhydrazo‐Benzoylacetone Ligand: Synthesis,Characterization and Biological Study

A new series of binary mononuclear complexes were prepared from the reaction of the hydrazone ligand, 2-carboxyphenylhydrazo-benzoylacetone (H2L), with the metal ions, Cd(II), Cu(II), Ni(II), Co(II), Th(IV) and UO2(VI). The binary Cu(II) complex of H2L was reacted with the ligands 1,10-phenanthroline or 2-aminopyridine to form mixed-ligand complexes. The binary complexes of Cu(II) and Ni(II) are suggested to have octahedral configurations. The Cd(II) and Co(II) complexes are suggested to have tetrahedral and/or square-planar geometries, respectively. The Th(IV) and UO2(VI) complexes are suggested to have octahedral and dodecahedral geometries, respectively. The mixed-ligand complexes have octahedral configurations. The structures of all complexes and the corresponding thermal products were elucidated by elemental analyses, conductance, IR and electronic absorption spectra, magnetic moments, 1H NMR and TG-DSC measurements as well as by mass spectroscopy. The ligand and some of the metal complexes were found to activate the enzyme pectinlyase.     

Removal of uranyl ions from wastewaters using cellulose and modified cellulose materials</p> </p>

Summary Three silylcellulosic derivatives with different substitution degree were examined as sorbents for uranyl ions. The adsorption rate and capacity of cellulose and modified cellulose were investigated in aqueous media, at various pH and temperature values. The polymer - metal complexes of UO₂²⁺ were characterized by infrared and electronic spectra, and thermogravimetry. The thermal behavior of cellulose (C), trimethylsilyl - cellulose (tmsc, SD= 2.85) and triphenylsilyl - cellulose (TPSC1, SD=2.89 and TPSC2, SD =2.70) and their complexes with uranyl ions in atmospheric air has been studied between room temperature and 600 °C. The Coats-Redfern method was applied to estimate the kinetic parameters. The results revealed that the complexation of C and TMSC with UO₂²⁺ increases the thermal stability.</p> </p>     

Synthesis and characterization of di- and triorganotin(IV) complexes of 2-tert-butyl-4-methyl phenol

The di- and trialkyltin(IV) complexes of composition R₂SnCl_2−x (OAr), and n-Bu₃Sn(OAr) (R = n-Bu and Me; x = 1 and 2; OAr = OC₆H₃Bu ^t -2-Me-4) have been synthesized by the reactions of di-n-butyl and dimethyltin dichlorides and tri-n-butyltin(IV) chloride with 2-tert-butyl-4-methylphenol and triethylamine in tetrahydrofuran. The reaction of triphenyltin chloride with trimethylsilyl-2-t-butyl-4-methylphenoxide in the same solvent however, gives a complex of composition Ph₃Sn(OAr). The complexes have been characterized by microanalyses, molar conductance measurements, molecular weight determinations and IR and ¹H, ¹³C and ¹¹⁹Sn NMR and mass spectral studies. Thermal behaviour of the complexes has been studied by TGA and DTA techniques. From the non-isothermal TG data, the kinetic and thermodynamic parameters have been calculated employing Coats-Redfern equation and the mechanism of decomposition has been computed using non-isothermal kinetic method. Thermal investigations on the blends of poly(methylmethacrylate). PMMA, with organotin(IV)-2-tert-butyl-4-methylphenoxides have shown increased thermal stability compared to pure PMMA suggesting thereby their potential as additives towards PMMA.     

Thermal studies on some organotin(IV) complexes with piperidine and 2-aminopyridine dithiocarbamates

The complexes of piperidine dithiocarbamate, 2-aminopyridine dithiocarbamate and organotin(IV) of the type R₃Sn(L¹), R₂Sn(L¹)₂, R₃Sn(L²), R₂Sn(L²)₂, [R=C₆H₅CH₂ (benzyl), p-ClC₆H₄CH₂ (p-chlorobenzyl), L ¹=sodium piperidine dithiocarbamate and L ²=sodium 2-aminopyridine dithiocarbamate] have been synthesised and characterised by spectral studies (IR, UV, ¹H NMR). Thermogravimetric (TG) and differential thermal analytical (DTA) studies have beeen carried out for these complexes and from the TG curves, the order and apparent activation energy for the thermal decomposition reactions have been elucidated. The various thermal studies have been correlated with some structural aspects of the complexes concerned. From DTA curves, the heat of reaction has been calculated.     

Extraction of U(VI), Zr(IV) and Th(IV) from perchlorate media, by PC-88A

Extraction of U(VI), Zr(IV) and Th(IV) has been investigated from perchlorate media using 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (PC-88A) dissolved in toluene. The extraction of U(VI), Zr(IV) and Th(IV) was found to be quantitative in the pH range 1.6 to 3.2, 2.0 to 4.7 and 2.3 to 3.8, respectively, with 3.0^.10^-3, 5.6^.10^-4 and 1.0^.10^-2M PC-88A dissolved in toluene. U(VI) was stripped with 4.0M HCl, Zr(IV) with 2.5M NaF and Th(IV) with 8.0M HCl from the metal loaded organic phase containing PC-88A dissolved in toluene. The probable extracted species have been ascertained by plotting log D vs. log [HR] as UO₂R₂ ^.2HR, ZrR₄ ^.2HR and ThR₄ ^.4HR, respectively. U(VI) was separated from Zr(IV) and Th(IV) and from other associated metals. This method was proved by the determination of U(VI) in some real samples.     

Ligational behaviour of lomefloxacin drug towards Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Th(IV) and UO(2)(VI) ions: synthesis, structural characterization and biological activity studies

Nine new mononuclear Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Th(IV) and UO₂(VI) complexes of lomefloxacin drug were synthesized. The structures of these complexes were elucidated by elemental analyses, IR, XRD, UV–vis, ¹H NMR as well as conductivity and magnetic susceptibility measurements and thermal analyses. The dissociation constants of lomefloxacin and stability constants of its binary complexes have been determined spectrophotometrically in aqueous solution at 25 ± 1 °C and at 0.1 M KNO₃ ionic strength. The discussion of the outcome data of the prepared complexes indicate that the lomefloxacin ligand behaves as a neutral bidentate ligand through OO coordination sites and coordinated to the metal ions via the carbonyl oxygen and protonated carboxylic oxygen with 1:1 (metal:ligand) stoichiometry for all complexes. The molar conductance measurements proved that the complexes are electrolytes. The powder XRD study reflects the crystalline nature for the investigated ligand and its complexes except Mn(II), Zn(II) and UO₂(II). The geometrical structures of these complexes are found to be octahedral. The thermal behaviour of these chelates is studied where the hydrated complexes lose water molecules of hydration in the first steps followed by decomposition of the anions, coordinated water and ligand molecules in the subsequent steps. The activation thermodynamic parameters are calculated using Coats–Redfern and Horowitz–Metzger methods. A comparative study of the inhibition zones of the ligand and its metal complexes indicates that metal complexes exhibit higher antibacterial effect against one or more bacterial species than the free LFX ligand. The antifungal and anticancer activities were also tested. The antifungal effect of almost metal complexes is higher than the free ligand. LFX, [Co(LFX)(H₂O)₄]·Cl₂ and [Zn(LFX)(H₂O)₄]·Cl₂ were found to be very active with IC50 values 14, 11.2 and 43.1, respectively. While, other complexes had been found to be inactive at lower concentration than 100 μg/ml.     

Synergistic effect of HBMPPT with PSO, DOSO and TBP on the extraction of U(VI) and on the separation of U(VI) and Th(IV)

Some popular neutral extractants (PSO-petroleum sulfoxide, DOSO-di-n-octyl sulfoxide, TBP-tributylphosphate etc.) were chosen as synergist to study the synergistic effect on the extraction reaction with HBMPPT (4-benzoyl-2,4-dihydro-5-methyl-2-phenyl-3H-pyrazol-3-thione) for U(VI), and the synergistic separation ability of HBMPPT for U(VI) and Th(IV). The synergistic extraction ability shown by the studied systems for U(VI) is as follows: PSO>DOSO>TBP, and the same sequence was also verified for the separation coefficient of U(VI) and Th(IV). The synergistic complexes may be presented as: UO₂NO₃·BMPPT·S and UO₂(BMPPT)₂·S for U(VI) (S is PSO, DOSO or TBP).     

Synergistic extraction of U(VI) and Th(IV) from nitric acid with 4-benzoyl-2,4-dihydro-5-methyl-2-phenyl-3H-pyrazol-3-thione (HBMPPT) and tri-n-octylphosphine oxide (TOPO) in toluene

The extractant HBMPPT (4-benzoyl-2,4-dihydro-5-methyl-2-phenyl-3H-pyrazol-3-thione) was synthesized from HBMPP. Its m.p. was 106–108°C. The synergistic extraction of U(VI) and Th(IV) from nitric acid solution by HBMPPT and TOPO in toluene was studied. The extraction ability of HBMPPT was not so high as that of its parent (HBMPP), but when a little tri-n-octylphosphine oxide (TOPO) was added the ability to extract U(VI) and Th(IV) was seriously improved. The synergistic extracted complexes may be presented as UO₂NO₃·BMPPT·TOPO and UO₂(BMPPT)₂·TOPO for U(VI), and Th(NO₃)₃·BMPPT·TOPO and Th(NO₃)₂(BMPPT)₂·TOPO for Th(IV) respectively.     

Syntheses and spectrothermal studies of triethanolamine complexes of Co(II), Ni(II), Cu(II) and Cd(II) squarates

The triethanolamine complexes, [M(tea)₂]sq·nH₂O, (n=2 for Co(II), n=0 for Ni(II), Cu(II) and n=1 for Cd(II), tea=triethanolamine, sq²⁻=squarate), have been synthesized and characterized by elemental analyses, magnetic susceptibility and conductivity measurements, UV-Vis and IR spectra, and thermal analyses techniques (TG, DTG and DTA). The Co(II), Ni(II) and Cu(II) complexes possess octahedral geometry, while the Cd(II) complex is monocapped trigonal prismatic geometry. Dianionic squarate behaves as a counter ion in the complexes. The thermal decomposition of these complexes takes place in three stages: (i) dehydration, (ii) release of the tea ligands and (iii) burning of organic residue. On the basis of the first DTG_max of the decomposition, the thermal stability of the anhydrous complexes follows the order: Ni(II), 289°C>Co(II), 230°C>Cu(II), 226°C>Cu(II), 170°C in static air atmosphere. The final decomposition products — the respective metal oxides — were identified by FTIR spectroscopy.     

A thermal behaviour and structural study of bis(hydroxamato)oxovanadium(IV) complexes

The bis(hydroxamato)oxovanadium(IV) complexes of composition [VO(IAH)₂)] (I), [VO(IBH)₂)] (II) and [VO(ICH)₂)] (III) (where IAH = indole-3-acetohydroxamate; (C₉H₈NCONHO^?); IBH = indole-3-butyrohydroxamate; (C₁₁H₁₂NCONHO^?); ICH = indole-2-carbohydroxamate; (C₈H₆NCONHO^?)) synthesized form the reactions of VOSO₄·5H₂O with bi-molar amounts of potassium salts of the respective hydroxamic acids in methanol have been characterised by elemental analyses, magnetic moment measurements and IR spectral studies. The thermal behaviour of complexes has been studied by TG and DTA techniques. Thermograms indicated that all complexes decompose in two steps yielding [VO(IAH)], [VO(IBH)] and [VO(ICH)] as intermediate of respective complexes and VO₂ as the final product of decomposition in each case. From the initial decomposition temperatures (IDT), the order of thermal stability for the complexes has been inferred as II > I > III.     

Formation Constant of Dialkyltin(IV)-N-(Alkyl)-2/3-mercaptoacetamide Systems

The thermodynamic formation constants of N-(alkyl)-2- and/or 3-mercaptoacetamides complexes with dimethyl-, diethyl-, and n-dibutyltin(IV) cations have been determined potentiometrically in a dioxane-water mixture (75% v/v) at 30 ± 0.1°C in μ = 0.1 M NaCl using the Irving-Rossotti method and refined by the least-squares method. The basicity of the ligands follows the order C₂H₅NHCOCH₂SH > n-C₃H₇NHCOCH₂SH > n-C₄H_gNHCOCH₂SH > C₂H₅NHCOCH₂CH₂SH > n-C₃H₇NHCOCH₂CH₂SH > n-C₄H_g- NHCOCH CH SH. For each ligand the stability order of dialkytin(IV) complexes decreases as follows: [Me₂Sn(IV)]²⁺ >[Et Sn(IV)]²⁺ > [n-Bu₂Sn(IV)]^2+. This order is consistent with the group electronegativities of [R₂Sn(IV)]²⁺ cations calculated from Sanderson's electronegativity scale.     

Synthesis,structural studies and bio-activity of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) complexes with p -amino acetophenone salicyloyl hydrazone

Complexes of the type [M(pash)Cl] and [M(Hpash)(H₂O)SO₄] (M=Mn(II), Co(II), Ni(II), Cu(II) and Zn(II); Hpash = p-amino acetophenone salicyloyl hydrazone) have been synthesized and characterized by elemental analyses, molar electrical conductance, magnetic moments, electronic, ESR and IR spectra, thermal studies and X-ray powder diffraction. All the complexes are insoluble in common organic solvents and are non-electrolytes. The magnetic moment values and electronic spectra indicate a square-planar geometry for Co(II), Ni(II) and Cu(II) chloride complexes and spin-free octahedral geometry for the sulfato complexes. The ligand coordinates through >C=N–,–NH₂ and a deprotonated enolate group in all the chloro complexes, and through >C=N–, >C=O and–NH₂ in the sulfato complexes. Thermal analyses (TGA and DTA) of [Cu(pash)Cl] show a multi-step exothermic decomposition pattern. ESR spectral parameters of Cu(II) complexes in solid state at room temperature suggest the presence of the unpaired electron in d _{x ² ? y ²} . X-ray powder diffraction parameters for [Cu(pash)Cl] and [Ni(Hpash)(H₂O)SO₄] correspond to tetragonal and orthorhombic crystal lattices, respectively. The complexes show a fair degree of antifungal activity against Aspergillus sp., Stemphylium sp. and Trichoderma sp. and moderate antibacterial activity against E. coli and Clostridium sp.     

Thermal Studies on Some Ionic Chelates of Hafnium(IV)

Ionic chelate complexes of kojic acid(I) and hafnium(IV) of the type [(η⁵-C₅H₅)₂HfL]⁺[MCl₃]^– (II)[HL=kojic acid; M=Zn(II), Cd(II), Hg(II), Cu(II)] have been synthesised and characterised by spectral studies (IR, UV, ¹H NMR and ¹³CNMR). Thermogravimetric (TG) and differential thermal analytical (DTA) studies have been carried out for these complexes and from the TG curves, the order and apparent activation energy for the thermal decomposition reactions have been elucidated. The various thermal studies have been correlated with some structural aspects of the complexes concerned. From DTA curves, the heat of reaction has been calculated. This revised version was published online in July 2006 with corrections to the Cover Date.