Adsorption of antimony(III) and antimony(V) on bentonite: Kinetics, thermodynamics and anion competition

This research attempted to study the adsorption of Sb(III) and Sb(V) on bentonite using batch experiments. The effects of reaction time, temperature, initial Sb concentration, and competitive anions at different concentrations on the adsorption of Sb(III) and Sb(V) were investigated. Kinetic studies suggested that the adsorption equilibriums for both Sb(III) and Sb(V) were reached within 24 h. The desorption of Sb adsorbate on the bentonite was observed following Sb(III) adsorption, probably due to the oxidation of Sb(III) on the bentonite surface and subsequent desorption of Sb(V). In addition, oxidation of Sb(III) can occur in the solution medium also, which decreases the concentration of Sb(III) in the solution thereby driving the equilibrium in the direction of desorption from the surface. The adsorption data at three temperatures were successfully modeled using Langmuir (r² > 0.82) and Freundlich (r² > 0.99) isotherms. The thermodynamic parameters (ΔG⁰, ΔH⁰, and ΔS⁰) were calculated from the temperature dependence, suggesting that the adsorption process of Sb(III) is spontaneously exothermic, while the adsorption process of Sb(V) is spontaneously endothermic. Competitive anions such as , , and hardly affected the Sb(III) adsorption on bentonite, while and could compete with for adsorption sites. The competition between and on adsorption sites was presumably due to the formation of surface complexes and the surface accumulation or precipitation of on bentonite surface.     

Synthesis,characterizations and crystal structures of new antimony (III) complexes with dithiocarbamate ligands

Eight new antimony (III) complexes containing dithiocarbamate ligands (R₂NCS₂)₂SbBr [R₂NCS₂ = OC₄H₈NCS₂ (1), C₂H₅NC₄H₈NCS₂ (2), Me₂NCS₂ (3), C₄H₈NCS₂ (4)] and (R₂NCS₂)₃Sb[R₂NCS₂ = C₅H₁₀NCS₂ (5), Bz₂NCS₂ (6), Et₂NCS₂ (7), (HOCH₂CH₂)₂NCS₂ (8)] have been synthesized by the reactions of antimony (III) halides with dithiocarbamate ligands in 1:2 or 1:3 stoichiometries. All the complexes have been characterized by elemental analysis, melting point as well as spectral [IR and NMR (¹H and ¹³C)] studies. The crystal structures of complexes 1, 5 and 8 have been determined by X-ray single crystal diffraction, and their electrochemical character has also been studied.     

Synthesis and characterization of β-diketiminato complexes of antimony (III) halides

Treatment of SbX₃ (X = Br, Cl) with DippnacnacLi (Dippnacnac = [{N(C₆H₃ⁱPr₂2,6)C(Me)}₂CH]⁻) or Mesnacnac (Mesnacnac = [{N(Mes)C(Me)}₂CH]⁻, Mes = 2,4,6, trimethyl benzene) affords different products that are dependent on the stoichiometry of the reaction and the halide precursor. When DippnacnacLi is reacted with SbBr₃, C-H activation of the ligand backbone is observed and an asymmetric, bridged bromide dimer is isolated. In comparison, the reaction of SbCl₃ with MesnacnacLi affords monomeric MesnacnacSbCl₂. The solid-state structures were determined using X-ray crystallography.     

2-Acetylpyridine- and 2-benzoylpyridine-derived thiosemicarbazones and their antimony(III) complexes exhibit high anti-trypanosomal activity

Complexes [Sb(2Ac4oClPh)Cl₂] (1), [Sb(2Ac4oFPh)Cl₂] (2), [Sb(2Ac4oNO₂Ph)Cl₂] (3), [Sb(2Bz4oClPh)Cl₂] (4), [Sb(2Bz4oFPh)Cl₂] (5) and [Sb(2Bz4oNO₂Ph)Cl₂] (6) were obtained with 2-acetylpyridine-N(4)-ortho-chlorophenyl thiosemicarbazone (H2Ac4oClPh) and its N(4)-ortho-fluor (H2Ac4oFPh) and N(4)-ortho-nitro (H2Ac4oNO₂Ph) analogues, and with the corresponding 2-benzoylpyridine-derived thiosemicarbazones (H2Bz4oClPh, H2Bz4oFPh, H2Bz4oNO₂Ph). The studied compounds are excellent inhibitors of Trypanosoma cruzi growth. H2Bz4oClPh and complexes (4) and (1) were the most trypanosomicidal.Upon coordination of H2Ac4oClPh to antimony(III) in 1, the therapeutic index (TI) goes from 10.58 to 14.35. However, the best values of TI were found for H2Bz4oClPh (TI = 1240) and H2Ac4oNO₂Ph (TI = 773). Structure-activity relationship (SAR) studies did not allow the establishment of correlations between the anti-trypanosomal activity and physico-chemical parameters, but correlations were found between the cytotoxicities and physico-chemical properties.     

Molecular complexation of free base meso-tetraarylporphyrins with antimony(III) chloride in free solvent media

The reaction of meso-tetraarylporphyrins (H₂t(Xp)p) with SbCl₃ under free solvent conditions affords green complexes with a 1:1 H₂t(X)pp:SbCl₃ ratio. These complexes have dimeric structures with a (μ-Cl)₂bridge. UV–VIS, ¹H NMR and ¹³C NMR spectra data show that the porphyrin core of [(H₂t(Xp)p)₂Sb₂Cl₆], similar to 1:2 (donor:acceptor) molecular complexes of meso-tetraarylporphyrins and porphyrin diacid, is distorted, thus two nitrogen atoms of pyrrolenine in a side of the porphyrin plane act as electron donors to an antimony atom of SbCl₃. Molecular complexation of meso-tetraarylporphyrins with SbCl₃ produces a large downfield shift for the NH signal, although there is no hydrogen bonding present.     

Thermodynamic studies of sitting-atop complexation between free base meso-tetraarylporphyrins and antimony(III) chloride in chloroform

Interaction of para, meta and ortho-substituted meso-tetraarylporphyrins, (H₂t(X)pp, X: OMe, Me, H and Cl) with SbCl₃ in chloroform solution afforded 1 : 1 sitting-atop (SAT) complexes ([(SbCl₃)(H₂t(X)pp)]). The formation constants were calculated by KINFIT and found to decrease with increasing temperature. The thermodynamic parameters, ΔH°, ΔS° and ΔG°, were obtained. Formation constants of these complexes change with changing substituent (X) on the aryl rings of H₂t(X)pp in the following order: (SbCl₃)H₂t(4-OMe)pp >?(SbCl₃)H₂t(4-Me)pp >?(SbCl₃)H₂tpp >?(SbCl₃)H₂t(4-Cl)pp >?(SbCl₃)H₂t(3-OMe)pp >?(SbCl₃)H₂t(3-Me)pp> (SbCl₃)H₂t(2-OMe)pp >?(SbCl₃)H₂t(2-Me)pp.     

Thermochemistry of Heteroatomic Compounds. Part 16*. Hydrolysis and Formation Enthalpies of P(III) and As (III) Halides

Abstract

The enthalpies of hydrolysis and formation of P(III) and As(III) halides of acyclic structure have been determined and discussed.     

Antimon(III)-butoxo-Verbindungen

Antimony(III)-butoxo Compounds Tri(tert.-butoxo)stiban 1 reacts with antimony(III) chloride dependent from the molar ratio to yield Sb(O^tBu)₂Cl 2 and Sb₄Cl₇O(O^tBu)₃ 3 resp ‥ 3 are discrete molecules with a cage structure. 2 is associated by oxygen bridges. The vibrational spectra of 1–3 are assigned.     

Neutrale Thiolate und ein Iodidthiolat von Antimon(III). Die Kristallstrukturen von Sb(SC6H5)3, Sb(SC6H2Me3-2,4,6)3 und SbI(SC6H2Me3-2,4,6)2

Neutral Thiolates and a Iodothiolate of Antimony(III). Crystal Structures of Sb(SC₆H₅)₃, Sb(SC₆H₂Me₃-2,4,6)₃, and SbI(SC₆H₂Me₃-2,4,6)₂ The crystal structures of Sb(SC₆H₅)₃ ( 1 ), Sb(SC₆ · H₂Me₃-2,4,6)₃ ( 2 ), and the novel compound SbI(SC₆H₂Me₃-2,4,6)₂ ( 3 ) have been determined by X-ray crystallography. In addition to the expected trigonal pyramidal coordination of antimony intermolecular interactions are observed for 1 (Sb … O: 363.3 pm) and 3 (Sb … S: 2 × 369.4 pm) but not for 2 . The reasons for these differences are discussed.     

Osmium (VIII)-mediated oxidation of arsenic (III)/antimony (III) by 1-equivalent oxidants

Os(VIII) catalysis of oxidation of As(III)/Sb(III) by 1-equivalent oxidants like Ce(IV) and Mn(III) in acid medium is studied. A multistep mechanism involving the intervention of the intermediate oxidation states of osmium is found to apply. Specific rates of different steps in the mechanism are estimated and used to calculate reaction rates which are in reasonable agreement with those of experiment.     

Determination of antimony content in natural water by graphite furnace atomic absorption spectrometry after collection as antimony(III)-pyrogallol complex on activated carbon

Antimony(III) was preconcentrated on activated carbon (AC) as the antimony(III)–pyrogallol complex. Prior to the preconcentration, antimony(V) was reduced to antimony(III) with potassium iodide and ascorbic acid. The antimony adsorbed on the AC was determined by graphite furnace atomic absorption spectrometry as an AC suspension. The method was applied to differential determination of trace amounts of antimony in natural water.     

Antimony(III) complexes with pyridine-derived thiosemicarbazones: Structural studies and investigation on the antitrypanosomal activity

The antimony(III) complexes [Sb(2Fo4Ph)Cl₂] (1), [Sb(2Ac4Ph)Cl₂] (2) and [Sb(2Bz4Ph)Cl₂] (3) were prepared with N(4)-phenyl-2-formyl- (H2Fo4Ph), 2-acetyl- (H2Ac4Ph) and 2-benzoylpyridine (H2Bz4Ph) thiosemicarbazones. The antimony(III) complexes presented antitrypanosomal activity against the epimastigote and trypomastigote forms of Trypanosoma cruzi. Complexes (1) and (2) exhibited higher activity than the reference drugs benznidazole and nifurtimox.     

Synthesis,characterization, structural elucidation and biological screening of some bis(diisobutyldithiophosphato)antimony(III) complexes

Abstract

Seven complexes of type [(C₄H₉ⁱ-O)₂PS₂]₂SbR have been synthesized by the reaction of chlorobis(diisobutyldithiophosphato)antimony(III) with mixed thio and/or oxo donor ligands in 1:1?M stoichiometry, where R?=?SC₆H₅, OOCC₆H₅, SCH₂COOH, SOCCH₃, OOCCH₃, SC₆H₄COOH and OOC(OH)C₆H₄. These newly synthesized derivatives have been characterized by different physicochemical (elemental analysis (C, H, S, Sb), melting point, molecular weight determination), spectral (UV, IR, NMR (¹H, ¹³C and ³¹P)) studies, as well as ESI mass, thermal, powder XRD and biological studies. In the final step of weight loss in thermogravimetric analysis, occurring in the range of 245–505?°C, the degradation of the C₆H₃CO moieties takes place and antimony sulfide (1/2?Sb₂S₃) is obtained as remaining material, which is useful in various aspects. Bonded to antimony the diisobutyldithiophosphato substituent behaves as an anisobidentate ligand, which is confirmed through spectral analysis. Powder XRD studies indicate that these compounds crystallize in a monoclinic crystal system with an unit cell volume of ～7074–7162 ų forming nano ranged (9.69–15.69?nm) crystallites. From the antimicrobial screening tests, bis(diisobutyldithiophosphato)antimony(III) thioglycolate (compound 3) has shown a maximum zone of inhibition (19?mm) against E. coli at 200?μg mL^?1 concentration.     

The Affinity of Gallium(III) and Indium(III) for Nitrogen Donor Ligands

Abstract

Dedicated to Professor Arthur Martell on the occasion of his seventy fifth birthday.

The complexes of In(III) and Ga(III) with a variety of nitrogen donor ligands were studied in aqueous solution by glass electrode potentiometry at 25°C in 0.1 M NaNO₃. The ligands were 2-aminomethylpyri-dine (AMPY), ethylenediamine (EN), N,N,N',N'-tetrakis(2-hydroxypropyl)ethylenediamine (THPED), and N,N-bis(2-hydroxyethyl)glycine (BICIN). A variety of mixed ligand complexes of the MLOH type were detected with many of the above ligands as L. The logK₁ values obtained were with Ga(III) 8.40 (AMPY), 7.94 (THPED) 12.72 (EN), and In(III) 7.6 (AMPY), 8.20 (THPED), and 7.06 (BICIN). These formation constants are discussed in relation to previous predictions that In(III) and Ga(III) would have a substantial chemistry with nitrogen donor ligands. Of particular interest is the Ga(III) system with EN, where a very stable Ga(EN)³⁺ complex is formed, but no higher complexes except for hydrolyzed species such as Ga(EN)OH²⁺ and Ga(EN)(OH)₂ ⁺.     

Spectrophotometry Determination of Arsenic(III) and Antimony(III) by Means of Isonicotinoylhydrazones of 4-Dimethylaminobezaldehyde (4-Dbih) and 2-Hydroxynaphthaldehyde (2-Hnih)

Abstract

4-DBIH and 2-HNIH react with As(III) and Sb(III) respectively, in CH₃COOH medium to form colored complexes stable in presence of EDTA. As(III) and Sb(III) do not react with 2-HNIH and 4-DBIH respectively, and the Sb(III)-2-HNIH complex is extractable into isoamyl alcohol. These behaviours were used for the spectrophotometry determination of As (III) and Sb(III) in presence of several cations.     

Preconcentration of inorganic antimony(III) in environmental samples by PSTH-Dowex microcolumn and determination by FI-ETAAS

A flow injection on-line sorption preconcentration system has been synchronously coupled to an electrothermal atomic absorption spectrometry (ETAAS) system for the selective determination of trace amounts of Sb(III) in water, soil and plant. The determination was achieved by selective complexation and sorption of Sb(III) with [1,5-bis(2-pyridyl)-3-sulphophenyl methylene thiocarbonohydarzide (PSTH) immobilized on an anion-exchange resin (Dowex 1× 8-200)] at a wide range of pH, quantitative elution with 50 μl of 2 M HNO₃ and subsequent ETAAS detection. ETAAS determination of the analyte was performed in parallel with the preconcentration of the next sample. Using a preconcentration time of 60 s and a sample loading flow rate of 2.8 ml min⁻¹, an enhancement factor of 12 was obtained in comparison with direct injection of 50 μl aqueous solution, resulting in a sampling frequency of 31 samples h⁻¹. The detection limit (3 s) was 2 μg l⁻¹ and the precision was 3.1% (R.S.D.) for 11 replicate determinations at 10 μg l⁻¹. The accuracy of the proposed method was demonstrated by analyzing one certified sample and different spiked samples.     

Complex formation constants and thermodynamic parameters for La(III) and Y(III)L-serine complexes

Summary The stoichiometric stability constants for La(III) and Y(III)L-serine complexes were determined by potentiometric methods at different ionic strengths adjusted with NaClO₄ and at different temperatures. The overall changes in free energy (G ^o), enthalpy (H ^o), and entropy (S ^o) during the protonation ofL-serine and that accompanying the complex formation with the metal ions have been evaluated.

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Komplexbildungskonstanten und thermodynamische Parameter für La(III)- und Y(III)-L-Serin-Komplexe

Zusammenfassung Die stöchiometrischen Komplexbildungskonstanten für La(III)- und Y(III)-L-Serin-Komplexe wurden mittels potentiometrischer Methoden bei verschiedenen Ionenstärken (mit NaClO₄ adjustiert) und bei verschiedenen Temperaturen bestimmt. Die Änderungen in der freien Energie (G ^o), Enthalpie (H ^o) und Entropie (S ^o) während der Protonierung und der Komplexbildung mit den Metallionen wurden ermittelt.

     

Chemoselective conversion of aromatic epoxide and 1,2-diol to 1,3-dioxane derivatives with phenyltrimethylammonium tribromide in the presence of a catalytic amount of antimony(III) bromide

trans-Stilbene oxide was oxidatively converted to 2-phenyl-1,3-dioxanes with phenyltrimethylammonium tribromide in the presence of various 1,3-diols and a catalytic amount of SbBr₃ in DMSO at room temperature. Aromatic 1,2-diol, such as hydrobenzoin, was similarly converted to 2-aryl-1,3-dioxane derivatives under the same reaction conditions.     

Interaction of antimony(III) chloride with thiourea, 2-mercapto-5-methyl-benzimidazole, 3-methyl-2-mercaptobenzothiazole, 2-mercaptopyrimidine,and 2-mercaptopyridine

New antimony(III) chloride complexes with heterocyclic thioamides, thiourea (TU), 2-mercapto-5-methyl-benzimidazole (MMBZIM), 3-methyl-2-mercaptobenzothiazole (MMBZT), 2-mercaptopyrimidine (PMT), 2-mercaptopyridine (PYT) of formulae [SbCl₃(TU)₂] (1), [SbCl₃(MMBZIM)₂] (2), [SbCl₃(MMBZT)₂] (3), [SbCl₃(PMT)₂] (4), [SbCl₃(μ ₂-S)(PYT)₂] (5) were synthesized and characterized by elemental analysis, FT-IR and FT-Raman spectroscopies, and TG-DTA analysis. The crystal structure of 5 was also determined by X-ray diffraction. [C₁₀H₁₀Cl₃N₂S₂Sb] (5) crystallizes in space group C2/c, with a?=?25.0169(10)?Å, b?=?9.7952(3)?Å, c?=?12.9329(5)?Å, β?=?109.702(4)°, and Z?=?8. Crystals of 5 grown from acetonitrile solutions adopt a square-pyramidal geometry. The equatorial plane is formed by three chlorides and one sulfur atom from the thione ligand while the second sulfur is axial. The complexes were evaluated for their biological activities and compared with [SbCl₃(MMI)₂] (6) (MMI?=?2-mercapto-1-methylimidazole) and other isostructural ones. The complexes showed moderate cytostatic activity against murine leukemia cells (L1210), murine mammary carcinoma cells (FM3A), human T-lymphocyte (Molt4/C8, CEM), and human cervix carcinoma (HeLa) cells. The chloro and iodo derivatives show better cytostatic activity than the bromo ones.     

Synthesis and Characterization of Some New Organoantimony(III) Derivatives of N,S Donor Bifunctional Tetradentate Schiff Bases

Reactions of triphenylantimony(III) with the corresponding Schiff bases in equimolar ratios yield the phenylantimony(III) derivatives, PhSb[RC(NC 6 H 4 S)CH 2 (NC 6 H 4 S)CCOOCH 3 ] (R = C 6 H 5 , 4-ClC 6 H 4 , 4-BrC 6 H 4 , and 4-CH 3 C 6 H 4 ). These derivatives have been characterized by elemental analyses, molecular weight measurements, and IR as well as NMR ( 1 H and 13 C) spectral studies which reveal a five coordination around the central antimony atom.