An unexpected influence of the nature of the amine on the crystal structure of some Co(III)-Bi(III) heterobimetallic complexes

Two novel cobalt(III)-bismuth(III) heterometallic compounds [Co(NxH)₂(An)₂]₂[Bi(EDTA)(H₂O)]₂ · 7H₂O (1) and [Co(NxH)₂(p-Tol)₂][Bi(EDTA)] · 4H₂O (2) [An-aniline, p-Tol-para-toluidine, NxH-1,2-cyclohexanedionedioximate-ion, EDTA-ethylenediaminetetraacetate-ion] have been synthesized and characterized by NMR, thermogravimetry and single X-ray crystallography. Substitution of the aniline by para-toluidine molecules leads to radical changes in the anionic sub-lattice: from monomeric form to polymeric one. The coordination number of bismuth is 7+1 in 1, and 8 in 2; Bi coordination polyhedron in 1 can be described as a two-capped trigonal prism, while in 2 as a dodecahedron. The Co atoms in 1 and 2 have an octahedral coordination. NMR spectroscopy in DMSO solution confirms the trans-configuration of the complex cations in 1 and 2 by observation of a broad singlet of two symmetric hydrogen bonds. The NCH₂CH₂N component of EDTA ligand is in the domain of the fast exchange and the signal from this group is a singlet, while four acetate methylene protons give rise to an AB quartet system. It was shown that thermolysis of 1 and 2 occurs in three successive stages, via the dehydration, pyrolysis of the ligands and, finally, the formation of a sillenite-type phase Bi_26−xCo_xO_40−δ and small quantities of Co₃O₄.     

Cobalt(III) complexes of some aromatic thiohydrazides - Synthesis, characterization and structure

[Co(NH₃)₅Cl]Cl₂ forms neutral 1:3 complex by reaction with aromatic thiohydrazides, i.e. thiobenzhydrazide, o-hydroxythiobenzhydrazide, thiophen-2-thiohydrazide and furan-2-thiohydrazide. All these complexes are diamagnetic and have been characterized by elemental analysis and combination of spectroscopic methods. Cyclic voltammometry of the complexes shows irreversible metal centered and ligand centered electron transfer reactions. One complex, tris-o-hydroxythiobenzhydrazidocobalt(III), has been crystallized from DMSO solution to produce solvated crystals and its structure has been established by X-ray crystallography. Cobalt(III) ion is linked through three hydrazinic nitrogen and three sulfur atoms of three identical deprotonated ligand molecules in a distorted octahedral environment. Involvement of -OH group in intramolecular and intermolecular hydrogen bonding is crucial for crystal formation.     

Octahedral Co(III) complexes of 2-(phenylimino)pyrrolyl ligands: Synthesis and structural characterisation

The reactions of CoCl₂ with three equivalents of 2-(phenylimino)pyrrolyl sodium salts, performed under a nitrogen atmosphere, lead to the formation of the Co(III) complexes [Co(κ²N,N′-NC₄H₃C(H)N-C₆H₅)₃] (2a), [Co(κ²N,N′-NC₄H₃C(CH₃)N-C₆H₅)₃] (2b) and [Co(κ²N,N′-NC₁₆H₉C(H)N-C₆H₅)₃] (2c), accommodating three chelating iminopyrrolyl ligands. Complexes 2a-c were obtained in moderate yields, and their characterisation by ¹H, ¹³C NMR and X-ray diffraction show they are diamagnetic and have an octahedral geometry about the cobalt centre, respectively. Uncharacterised products were obtained in the same reaction involving ligand precursors such as 2-(2,6-dimethylphenylimino)pyrrolyl sodium salts, which is attributed to a greater steric hindrance in the coordination of three of these bulkier ligands. The redox behaviour of complexes 2a-c shows an irreversible reduction wave with a peak potential in the range −3.2 to −3.7 V. Upon reduction, the complexes decompose giving rise, in the case of 2a, to a redox pattern compatible with the formation of [Co(κ²N,N′-NC₄H₃C(H)N-C₆H₅)₂].     

High-coordinated lanthanum(III) complexes with new mono- and bidentate phosphoryl donors; spectroscopic and structural aspects

Monodentate and bidentate ligands PhNHP(O)(NC₄H₈O)₂ (1) and PhC(O)NHP(O)(NH(tert-C₄H₉))₂ (2) were used to prepare new 7, 9 and 10-coordinated lanthanum(III) complexes; La(1)₂Cl₃(H₂O)₂ (3), La(1)₂(NO₃)₃H₂O.La(1)₂(NO₃)₃CH₃CN (4) and La(2)₂(NO₃)₃ (5), respectively. Crystallization of compound 2 in CH₃OH:CH₃CN leads to one conformer in contrast to the crystallization result from CHCl₃:n-C₇H₁₆ (two conformers). Compound 4 contains two independent nine-coordinated La(III) complexes that are different in the solvated molecules (H₂O and CH₃CN). Some structural and electronic perturbations in coordinated ligand were occurred upon complexation, that are confirmed by increase of ²J_PH, ³J_PH and ⁶J_PH coupling constants from the free ligand 1 to complexes 3 and 4. The steric repulsions in the first coordination sphere of La³⁺ ion, metal-ligand (M-L) binding strength and PO stretching frequency are very influenced by changing the counter ion from Cl⁻ to . Comparing the X-ray crystallography data of free ligand 2 with bis-chelated complex 5, it is found that the phosphoryl group is more reactive than carbonyl counterpart. A blue shift of the ν(N-H) vibration is observed in line with the weakening of the hydrogen bond from N-H···O_Phosphoryl in 1 to N-H···Cl in 3. Three dimensional butterfly-shape structures are seen in the unit cell of complex 3, which are produced by O_Water-H···O_Morpholine hydrogen bonds.     

Synthesis and structural determination of new octaethylporphyrin iron(III) complexes containing cyanamide derivatives as axial ligand

The reactions of heme, [OEPFeCl] where OEP is the dianion of octaethylporphyrin, with phenylcyanamide (pcyd) ligands have been studied. Four new porphyrin complexes, [OEPFe(L)] (L = pcyd (2), 2-Clpcyd (3), 2-Mepcyd (4), 2,4-Me₂pcyd (5)), have been isolated and characterized by spectroscopic methods. ¹H NMR spectroscopy reveals that the species [OEPFe(L)] are paramagnetic and iron is five-coordinate. The structure of [OEPFe(pcyd)] (2) has been determined by X-ray diffraction analysis. The four Fe-N, bond distances have average values of 2.062 Å. The average displacement of the iron(III) atom from the mean porphinato core is 0.45 Å. Electrochemical of [OEPFe(L)] (L = pcyd (2), 2-Clpcyd (3), 2-Mepcyd (4), 2,4-Me₂pcyd (5)) have been studied by cyclic voltammetry.     

Polymerization study of o-Si(OH)4 and complexation with Am(III), Eu(III) and Cm(III)

The stability constants of Am⁺³, Cm³⁺ and Eu³⁺ with ortho silicate, were measured at pH 3.50 and in ionic strengths of 0.20-1.00 M (NaClO₄) by the solvent extraction method. The Am⁺³, Cm³⁺ and Eu³⁺ forms 1:1 complex with ortho silicate ion at pH 3.60 with the stability constant (log β₁) value of 8.02 ± 0.10, 7.78 ± 0.08 and 7.81 ± 0.11, respectively. The stability of these metal ions decrease with increased ionic strength from 0.20 to 1.00 M (NaClO₄) for silicic acid concentrations of 0.002-0.020 M. Increasing silicic acid concentration above 0.02 M increased the amount of M³⁺ extracted into the organic phase, contrary to the trend usually observed for increased ligand concentration in solvent extraction. This reversed trend is likely due to the extraction of cationic species of silicic acid by HDEHP. Aging time (60-300 min) had no effect on the stability constant of these metal ions for 0.002-0.020 M silicic acid at pH 3.50 and I = 0.20 M (NaClO₄).The fraction of polymeric silicic acid present in solutions of 0.20-4.50 M NaClO₄ solutions at pH 3.0-10.0, T = 0-60 °C and aging time = 5-300 min was measured for determination of the silicomolybdate reaction to ascertain the proper conditions to study metal-silicate complexation.     

Secondary ligand-metal interactions in rhodium(III) and iridium(III) phosphoramidite complexes

The synthesis, characterization, and application in asymmetric catalytic cyclopropanation of Rh(III) and Ir(III) complexes containing (S_a,R_C,R_C)-O,O′-[1,1′-binaphthyl-2,2′-diyl]-N,N′-bis[1-phenyl-ethyl]phosphoramidite (1) are reported. The X-ray structures of the half-sandwich complexes [MCl₂(C₅Me₅)(1,κP)] (M = Rh, 2a; M = Ir, 2b) show that the metal-phosphoramidite bond is significantly shorter in the Ir(III) analog. Chloride abstraction from 2a (with CF₃SO₃SiMe₃ or with CF₃SO₃Me) and from 2b (with AgSbF₆) gives the cationic species [MCl(C₅Me₅)(1,2-η-1,κP)]⁺ (M = Rh, 3a; M = Ir, 3b), which display a secondary interaction between the metal and a dangling phenethyl group (NCH(CH₃)Ph) of the phosphoramidite ligand, as indicated by NMR spectroscopic studies. Complexes 3a and 3b slowly decompose in solution. In the case of 3b, the binuclear species [Ir₂Cl₃(C₅Me₅)₂]⁺ is slowly formed, as indicated by an X-ray study. Preliminary catalytic tests showed that 3a cyclopropanates styrene with moderate yield (35%) and diastereoselectivity (70:30 trans:cis ratio) and with 32% ee (for the trans isomer).     

Stepwise selective oxidation of tris(2-(diphenylphosphino)ethyl)phosphine on thiolato palladium(II) complexes

One of the equatorially coordinated terminal phosphorus atoms of tris(2-(diphenylphosphino)ethyl)phosphine (pp₃) ligand on the five-coordinate trigonal-bipyramidal palladium(II) complex, [Pd(4-Cltp)(pp₃)](BF₄) (4-Cltp = 4-chlorothiophenolate), was selectively oxidized by photolysis to form the four-coordinate square-planar complex. Further selective oxidation of another coordinated terminal phosphorus atom proceeded quantitatively by the substitution reaction with 4-chlorothiophenolate. The solid state structures of these stepwise-oxidized square-planar complexes were determined by X-ray crystal structure analyses, and the structures of the starting trigonal-bipyramidal and the oxidized complexes in solution have been characterized by ³¹P NMR spectroscopy.     

Anti-Leishmanial activity of homo- and heteroleptic bismuth(III) carboxylates

Bismuth(III) complexes of NSAIDs (Non-Steroidal Anti Inflammatory Drugs) and substituted benzoic acids (o-methoxybenzoic acid, m-methoxybenzoic acid, o-nitrobenzoic acid, 3,5-diacetamidobenzoic acid, and 5-[(R/S)-2,3-dihydroxypropyl carbamoyl]-2-pyridine carboxylic acid) have been synthesised and fully characterised. Two new bis-carboxylato bismuth complexes have been characterised by single crystal X-ray diffraction, namely [PhBi(o-MeOC₆H₄CO₂)₂(bipy)]·0.5EtOH (bipy = 2,2'-bipyridine) and [PhBi(C₉H₁₁N₂O₃CO₂)₂(H₂O)]·6H₂O. All compounds were tested against the parasite Leishmania major promastigotes for their anti-Leishmanial activity and were further assessed for their toxicity to mammalian cells. The NSAID free acids and their bismuth derivatives show negligible anti-Leishmanial activity at concentrations 1.95 to 250 μg/mL against the promastigotes of L. major whereas in the case of mammalian cells only bismuth complexes of naproxen and mefenamic acid have significant effect at concentration ≥ 250 μg/mL. The bismuth(III) complexes of substituted benzoic acids show significant anti-Leishmanial activity against the promastigotes of L. major V121 at very low concentrations while their respective free carboxylic acids show no effective activity. However, the bismuth compounds inhibit the growth of the mammalian cells at all concentrations studied (1.95 to 500 μg/mL) following 48 h incubation. The comparatively low toxicity of BiCl₃ and Bi(NO₃)₃, suggests that overall toxicity of bismuth complexes towards the parasite is both ligand and metal dependent.     

The photolysis of octachlorodirhenate(III) in chloroform

Under 254 nm irradiation in chloroform, [Re₂Cl₈]²⁻ is converted cleanly to [Re₂Cl₉]⁻. The reaction is initiated primarily through light absorbed by the chloroform. The experimental rate expression is , where I₀ is the incident light intensity and f_S is the fraction of light absorbed by the solvent. The rate law is consistent with mechanisms involving either [Re₂Cl₈]⁻ or [Re₂Cl₉]²⁻ as an intermediate.     

Mononuclear single helices of lanthanum(III) and europium(III). Metal dependent diastereomeric excess

Using the 1:2 condensate of benzildihydrazone and 2-acetylpyridine as a tetradentate N donor ligand L, LaL(NO₃)₃ (1) and EuL(NO₃)₃ (2), which are pale yellow in colour, are synthesized. While single crystals of 1 could not be obtained, 2 crystallises as a monodichloromethane solvate, 2·CH₂Cl₂ in the space group Cc with a = 11.7099(5) Å, b = 16.4872(5) Å, c = 17.9224(6) Å and β = 104.048(4)°. From the X-ray crystal structure, 2 is found to be a rare example of monohelical complex of Eu(III). Complex 1 is diamagnetic. The magnetic moment of 2 at room temperature is 3.32 BM. Comparing the FT-IR spectra of 1 and 2, it is concluded that 1 also is a mononuclear single helix. ¹H NMR reveals that both 1 and 2 are mixtures of two diastereomers. In the case of the La(III) complex (1), the diastereomeric excess is only 10% but in the Eu(III) complex 2 it is 80%. The occurrence of diastereomerism is explained by the chiralities of the helical motif and the type of pentakis chelates present in 1 and 2.     

Synthesis and structural characterization of mixed-ligand silver(I) complexes containing diphosphazanes and bidentate N-donor ligands

The reactions of a self-assembled silver(I) coordination polymer, [Ag₂{μ-PrⁱN(PPh₂)₂}(μ-NO₃)₂]_n (1) with various bidentate N-donor ligands such as DABCO, 2,2′-bipyridyl and 1,10-phenanthroline yield 1-D helices or π-π stacked polymers, depending on the chelate vector of the N-donor ligand. The molecular structures of the resultant complexes, [Ag₂{μ-PrⁱN(PPh₂)₂}(DABCO)(NO₃)₂]_n (2), [Ag₂{μ-PrⁱN(PPh₂)₂}(2,2′-bipy)₂(NO₃)₂] (3) and [Ag₂{μ-PrⁱN(PPh₂)₂}(1,10-phen)₂](NO₃)₂ (4) have been confirmed by single-crystal X-ray diffraction. Complex 2 exists as an infinite helical polymer because of the exo-bidentate nature of DABCO. Complex 3 assumes a 2D grid motif as a result of intermolecular π-π stacking among adjacent bipyridine moieties. The phenanthroline complex 4 exhibits strong inter- and intramolecular π-π stacking interactions.     

The synthesis and characterisation of Rh(III) complexes with pyridyl triazole ligands

A series of Rh(III) mixed ligand polypyridine type complexes have been prepared. Complexes of the form [Rh(L)₂(L^′)]ⁿ⁺, where n=2/3, L=2,2^′-bipyridine (bpy)/1,10-phenanthroline (phen) and L^′=3-(pyridin-2-yl)-1,2,4-triazole (Hpytr), 1-methyl-3-(pyridin-2-yl)-1,2,4-triazole (1M3pytr), 4-methyl-3-(pyridin-2-yl)-1,2,4-triazole (4Mpytr), 3,5-bis(pyridin-2-yl)-1,2,4-triazole (Hbpt), 4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole (NH₂bpt) and 3-(pyridin-2-yl)-5-phenyl-1,2,4-triazole (HPhpytr), have been prepared and their synthesis and characterisation are reported. Crystals of [Rh(bpy)₂(Phpytr)](PF₆)₂ and [Rh(phen)₂(NHbpt)](PF₆)₂ were obtained and their structures determined. Analysis of X-ray crystallographic data showed that coordination of the metal centre in [Rh(phen)₂(NHbpt)](PF₆)₂ occurs via the amine moiety and a nitrogen of the pyridine ring. NMR studies illustrated that coordination to the NH₂bpt ligand was also possible via a nitrogen of the triazole ring and the pyridine ring forming the complex [Rh(phen)₂(NH₂bpt)](PF₆)₃. The absorption and emission properties of the complexes studied were found to be π-π^* in nature and preliminary evidence suggests that all complexes with the exception of [Rh(phen)₂(NHbpt)](PF₆)₂ and [Rh(bpy)₂(NHbpt)](PF₆)₂ are dual emitting at 77 K.     

Probing the antibacterial and anticancer potential of tryptamine based mixed ligand Schiff base Ruthenium(III) complexes

Development of new chemotherapeutic agents to treat microbial infections and recurrent cancers is of pivotal importance. Metal based drugs particularly ruthenium complexes have the uniqueness and desired properties that make them suitable candidates for the search of potential chemotherapeutic agents. In this study, two mixed ligand Ru(III) complexes [Ru(Cl)₂(SB)(Phen] (RC-1) and [Ru(Cl)₂(SB)(Bipy)] (RC-2) were synthesised and characterized by elemental analysis, IR, UV–Vis, ¹H, ¹³C NMR spectroscopic techniques and their molecular structure was confirmed by X-ray crystallography. Antibacterial activity evaluation against two Gram-positive (S. pneumonia and E. faecalis) and four Gram-negative strains (P. aurogenosa, K. pneumoniae, S. enterica, and E. coli) revealed their moderate antibacterial activity with MIC value of ≥250 μg/mL. Anticancer activity evaluation against a non-small lung cancer cell line (H1299) revealed the tremendous anticancer activity of these complexes which was further validated by DNA binding and docking results. DNA binding profile of the complexes studied by UV–Visible and fluorescence spectroscopy showed an intercalative binding mode with CT-DNA and an intrinsic binding constant in the range of 3.481–1.015× 10⁵ M⁻¹. Both the complexes were also found to exert weak toxicity to human erythrocytes by haemolytic assay compared to cisplatin. Potential of these complexes as anticancer agents will be further delineated by in vivo studies.     

Iron(III), chromium(III) and cobalt(II) complexes with squarate: Synthesis, crystal structure and magnetic properties

The preparation and variable temperature-magnetic investigation of three squarate-containing complexes of formula [Fe₂(OH)₂(C₄O₄)₂(H₂O)₄]·2H₂O (1) [Cr₂(OH)₂(C₄O₄)₂(H₂O)₄]·2H₂O (2) and [Co(C₄O₄)(H₂O)₄]_n (3) [H₂C₄O₄ = 3.4-dihydroxycyclobutene-1,2-dione (squaric acid)] together with the crystal structures of 1 and 3 are reported. Complex 1 contains discrete centrosymmetric [Fe₂(OH)₂(C₄O₄)₂(H₂O)₄] diiron(II) units where the iron pairs are joined by a di-μ-hydroxo bridge and two squarate ligands acting as bridging groups through adjacent oxygen atoms. Two coordinated water molecules in cis position complete the octahedral environment at each iron atom in 1. The iron-iron distance with the dinuclear unit is 3.0722(6) Å and the angle at the hydroxo bridge is 99.99(7)°, values which compare well with the corresponding ones in the isostructural compound 2 (2.998 Å and 99.47°) whose structure was reported previously. The crystal structure of 3 contains neutral chains of squarato-O¹,O³-bridged cobalt(II) ions where four coordinated water molecules complete the six-coordination at each cobalt atom. The cobalt-cobalt separation across the squarate bridge is 8.0595(4) Å. A relatively important intramolecular antiferromagnetic coupling occurs in 1 whereas it is very weak in 2, the exchange pathway being the same [J = −14.4 (1) and −0.07 cm⁻¹ (2), the spin Hamiltonian being defined as ]. A weak intrachain antiferromagnetic interaction between the high-spin cobalt(II) ions occurs in 3 (J = −0.30 cm⁻¹). The magnitude and nature of these magnetic interactions are discussed in the light of their respective structures and they are compared with those reported for related systems.     

Triclinic structural and magnetic properties of praseodymium(III) picrate triethylene glycol complex

A study on the structure and magnetic properties of [Pr(NO₃)(Pic)(H₂O)₂(EO3)](Pic) complex, where EO3 = triethylene glycol and Pic = picrate anion was conducted and characterized by single crystal X-ray structure analysis. Magnetic susceptibility (χ_M) was carried out from 2 to 300 K under both field-cooled (FC) and zero-field-cooled (ZFC) measurements with an applied magnetic field of 2000 Oe. The complex is crystallized in triclinic with space group . The coordination geometry around the Pr(III) ion was a tetradecahedron with a ten-coordination number. In the crystal, the molecular structure was stabilized by moderate and weak hydrogen bonding interactions between the cation [Pr(NO₃)(Pic)(H₂O)₂(EO3)]⁺ moiety and [Pic]⁻ as counter-anion that led to the formation of a one-dimensional network. The temperature dependence of the magnetic susceptibility of [Pr(NO₃)(Pic)(H₂O)₂(EO3)](Pic) shows the presence of weak antiferromagnetic interactions between the Pr(III) centers. The magnetic susceptibility for complex also obeys the Curie-Weiss law and is effective at high temperatures. Some factors that influence the photoluminescence intensity were also reported.     

Complexation study of europium(III) and curium(III) with urea in aqueous solution investigated by time-resolved laser-induced fluorescence spectroscopy

The complex formation of europium(III) and curium(III) with urea in aqueous solution has been studied at I = 0.1 M (NaClO₄), room temperature and trace metal concentrations in the pH-range of 1-8 at various ligand concentrations using time-resolved laser-fluorescence spectroscopy. While for curium(III) the luminescence maximum is red shifted upon complexation, in case of europium(III) emission wavelengths remain unaltered but a significant change in peak splitting occurs. Both heavy metals form weak complexes of the formulae ML³⁺ and MLOH²⁺ with urea. Stability constants were determined to be log β₁₁₀ = −0.12 ± 0.05 and log β_11-1 = −6.86 ± 0.15 for europium(III) and log β₁₁₀ = −0.28 ± 0.12 and log β_11-1 = −7.01 ± 0.15 for curium(III).     

Overcoming cisplatin resistance using gold(III) mimics: anticancer activity of novel gold(III) polypyridyl complexes

Gold(III) compounds have been recognized as anticancer agents due to their structural and electronic similarities with currently employed platinum(II) species. An added benefit to gold(III) agents is the ability to overcome cisplatin resistance. This work identified four gold(III) compounds, [Au(Phen)Cl₂]PF₆, [Au(DPQ)Cl₂]PF₆, [Au(DPPZ)Cl₂]PF₆, and [Au(DPQC)Cl₂]PF₆, (Phen = 1,10-phenanthroline, DPQ = dipyrido[3,2-d:2′,3′-f]quinoxaline, DPPZ = dipyrido[3,2-a:2′,3′-c] phenazine, DPQC = dipyrido[3,2-d:2′,3′-f] cyclohexyl quinoxaline) that exhibited anticancer activity in both cisplatin sensitive and cisplatin resistant ovarian cancer cells. Two of these compounds, [Au(DPQ)Cl₂]PF₆ (AQ) and [Au(DPPZ)Cl₂]PF₆ (AZ), displayed exceptional anticancer activity and were the focus of more intensive mechanistic study. At the molecular level, AQ and AZ formed DNA adducts, generated free radicals, and upregulated pro-apoptotic signaling molecules (p53, caspases, PARP, death effectors). Taken together, these two novel gold(III) polypyridyl complexes exhibit potent antitumor activity in cisplatin resistant cancer cells. These activities may be mediated, in part, by the activation of apoptotic signaling.     

Simultaneous determination of Fe(III) and Al(III) by first-derivative spectrophotometry and partial least-squares (PLS-2) method – Application to post-haemodialysis fluids

Derivative spectrophotometry (graphical method) and partial least-squares regression (numerical method) methods were developed for the spectrophotometric multi-component analysis of post-haemodialysis fluids and synthetic mixtures containing Al(III) and Fe(III) without any chemical separation. The complexes of these metal ions with chrome azurol S were formed immediately at pH 5.5 and were stable for at least 3h. The graphical method is based on the use of first-derivative spectra for evaluation because working wavelength determination was more precise and spectral overlap was less than in the ordinary spectra. Two wavelengths at which the complexes exhibited maximum absorption values for Fe(III) and Al(III) were selected as analytical wavelengths, i.e., 675 and 623.5nm, respectively. Lambert-Beer's law is obeyed between 0.0896-8.064mug/mL Fe(III) and 0.054-0.486mug/mL Al(III). Limits of detection for Fe(III) and Al(III) were 0.056 and 0.044mug/mL, respectively. The reproducibility, expressed as variation coefficients, for two sets of 10 standard mixtures containing 3.584mug/mL Fe(III) and 0.27mug/mL Al(III) were 1.9% and 2% for iron and aluminium, respectively. In the numerical method, a training set was randomly prepared by using 14 samples. The concentration of each component has been varied in the linear range of the analytical signal. The spectral regions between 510 and 720nm were selected for the analysis of the binary mixture of Fe(III)/Al(III). The proposed methods were validated by using synthetic binary mixtures and applied to the simultaneous determination of Fe(III) and Al(III) in post-haemodialysis samples. The obtained results were compared with each other; in general, both multi-component methods gave rise to similar recovery results for laboratory-prepared mixtures and real samples.