Lead Cations Research Articles

Benzoaza-15-crown-5 ethers: synthesis, structure, and complex formation with metal and ethylammonium ions

Benzoaza-15-crown-5 ethers containing one or two nitrogen atoms in different positions of the macrocycle and bearing different substituents at these atoms were synthesized. The structures of azacrown ethers and their metal complexes were studied by X-ray diffraction. The stability constants of the complexes of azacrown ethers with Na+, Ca2+, Ba2+, Ag+, Pb2+, and EtNH3+ ions were determined by 1H NMR titration in MeCN-d3. In free benzoazacrown ethers containing secondary nitrogen atoms bound to the benzene ring, as well as in N-acetyl derivatives, the N atoms are sp2-hybridized and have a planar geometry. The nitrogen lone pairs on the p orbitals are efficiently conjugated to the benzene ring or the carbonyl fragment of the acetyl group, which is unfavorable for the complex formation. In addition, the formation of complexes with benzoazacrown ethers containing secondary nitrogen atoms is hindered because the hydrogen atoms of the NH groups are directed to the center of the macrocyclic cavity. In benzoazacrown ethers bearing N-alkyl substituents or secondary nitrogen atoms distant from the benzene ring, the N atoms show a substantial contribution of the sp3-hybridized state and have a pronounced pyramidal configuration, which promotes the complex formation. The lead and calcium cations form the most stable complexes due to the high affinity of Pb2+ ions for O,N-containing ligands, a high charge density on these ions, and the better correspondence of the cavity size of the 15-membered macrocycles to the diameter of the Ca2+ ion. An increase in the stability of the complexes is observed mainly in going from monoazacrown ethers to diazacrown ethers containing identical substituents at the N atoms and in the following series of substituents: C(O)Me < H < Me < CH2CO2Et. In the case of the CH2CO2Et substituents, the carbonyl oxygen atom is also involved in the coordination to the cation. The characteristic features of the complexing ability of N-alkylbenzomonoaza-15-crown-5 ethers bearing the nitrogen atom conjugated to the benzene ring show that macro-cyclic ligands having this structure are promising as selective and efficient complexing agents for metal cations.

Different natural biomasses for lead cation removal

It is believed that some wastes play an important role on the pollution prevention. In this paper, three different natural biomasses were investigated as biosorbent. Salsola green plant which grown at Jubail (industrial area) in KSA, it is phyto remediation plant. Salsola is metal hyper accumulation plant, it adsorbed (23.5, 25.7 mg lead per gram stem or leaf) from soil. Also it can be reused as ion exchanger for pb 2+ from solution. Shrimp shell’s used for extraction of chitosan in laboratory with degree of substitution 81%. Chitosan and crosslinked carboxymethyl chitosan were investigated for pb 2+ adsorption and compared with crosslinked carboxymethyl corn cob. The adsorption experiments demonstrated that the three biomasses have high adsorption capacity for pb 2+, good reusability and stability for three cycles.

Tb-doped Aluminosilicate Oxyfluoride Scintillating Glass and Glass-ceramic

AbstractTwo aluminosilicate oxyfluoride glass systems, a lead-cadmium-aluminosilicate oxyfluoride and a lithium-lanthanum-aluminosilicate oxyfluoride, doped with different TbF3 concentrations, have been fabricated and investigated. By appropriate heat treatment of the as-prepared glasses above, transparent glass-ceramics (TGC) were obtained. The glass-ceramics contain Tb:Pb(Cd)F2 or Tb:LaF3 nano-crystals in the glass-matrix. Differential scanning calorimetry, Raman scattering, and luminescence under both UV and β-particle excitation have been investigated on as-prepared glasses and glass-ceramics. It has been found that the terbium-doped lithium-lanthanum-aluminosilicate oxyfluoride glass exhibits good UV excited luminescence and β-induced luminescence. The luminescence yield increases for glass-ceramic compared to that of the as-prepared glass. The including of LaF3 in the glass-matrix is beneficial for a higher Tb-doping concentration and a high light yield. The light yield of lithium-lanthanum-aluminosilicate oxyfluoride glass and glass-ceramic is comparable to that of Schott IQI-301 product. However, the terbium-doped lead-cadmium-aluminosilicate oxyfluoride glass and glass-ceramic have a detrimental luminescence performance. The lead cations in the glass-matrix may create non-bridging oxygen defects, which are a strong source of charge traps, and correlated to a strong Raman “Boson” peak.

Lead cation exchange and alumina columns for concentration of 99mTc-pertechnetate

Large columns containing aluminum oxide (Al2O3) or gel (e.g. zirconium molybdate) are needed to prepare 98Mo(n,γ)99Mo→99mTc column chromatographic generators that results in large elution volumes containing relatively high 99Mo impurity and low concentrations of 99mTc. The decrease in radioactive concentration or specific volume concentration of 99mTc places a limitation on some pharmaceutical kits (DTPA, MIBI, ECD, etc.) or clinical procedures. We report on the post elution concentration of 99mTc using in house prepared lead cation-exchange and alumina columns. Using these columns high bolus volumes (10–60 mL 0.02M sodium sulfate) of 99mTc can conveniently be concentrated in 1 mL of physiological saline. This approach also works very effectively to prepare high specific volume solutions of 99mTc-pertechnetate from a fission based 99Mo/99mTc generator in the second week of its normal working life.

Raman and infrared structural investigation of (PbO)x(ZnO)(0.6−x)(P2O5)0.4 glasses

AbstractThe structure of ternary (PbO)x(ZnO)(0.6−x)(P2O5)0.4glasses was investigated using Raman scattering and infrared spectroscopy over the compositional range x = 0–0.6. No significant change of the average chain length composed by PO4 tetrahedral units with the substitution of zinc for the lead cation was observed. The linewidth and wavenumber variations of the Raman high‐wavenumber bands reflect the Zn/Pb substitution in these glasses and are correlated with the metal–oxygen force constant and local disorder. The infrared reflectivity spectra have been fitted with the four‐parameter dielectric function model. The variation in the 1000–1200 cm−1wavenumber range has been attributed to an increase of the oscillator damping ΓLO(PO3)2− as with PbO content vibrations rather than a variation of the chain length. Copyright © 2008 John Wiley &amp; Sons, Ltd.

Goethite surface reactivity: A macroscopic investigation unifying proton, chromate, carbonate, and lead(II) adsorption

The goethite surface structure has been extensively studied, but no convincing quantitative description of its highly variable surface reactivity as inversely related to its specific surface area (SSA) has been found. The present study adds experimental evidence and provides a unified macroscopic explanation to this anomalous behavior from differences in average adsorption capacities, and not in average adsorption affinities. We investigated the chromate anion and lead(II) cation adsorption behavior onto three different goethites with SSA varying from 50 to 94 m 2/g, and analyzed an extensive set of published anion adsorption and proton charging data for variable SSA goethites. Maximum chromate adsorption was found to occupy on average from 3.1 to 9.7 sites/nm 2, inversely related to SSA. Congruency of oxyanion and Pb(II) adsorption behavior based on fractional site occupancy using these values, and a site density analysis suggest that: (i) ion binding occurs to singly and doubly coordinated sites, (ii) proton binding occurs to singly and triply coordinated sites (ranging from 6.2 to 8 total sites/nm 2, in most cases), and (iii) a predominance of (210) and/or (010) faces explains the high reactivity of low SSA goethites. The results imply that the macroscopic goethite adsorption behavior may be predicted without a need to investigate extensive structural details of each specific goethite of interest.

Metal-Catalyzed Cleavage of tRNAPhe

This laboratory project is one component of a semester-long advanced biochemistry laboratory course that uses several complementary techniques to study tRNAPhe conformational changes induced by ligand binding. In this article we describe a set of experiments in which students assay metal-catalyzed hydrolysis of tRNAPhe using gel electrophoresis. tRNAPhe cleavage patterns are monitored in the presence of lead(II) and other metals cations. Small molecule ligands are also studied to determine their ability to enhance or inhibit lead(II)-catalyzed cleavage of tRNAPhe. Gel bands are quantified to determine ligand-binding equilibrium constants for the small molecule ligand–tRNAPhe adducts. By pooling class data from the metal and small molecule ligand experiments, students draw conclusions regarding how metal-catalyzed hydrolysis is affected by various parameters such as tRNAPhe structure, ligand charge, and inorganic chemistry of the metal ion complexes.

Supramolecular Organization in Lead Bromide Salts of Imidazolium-Based Ionic Liquids

By heating imidazolium bromide-based ionic liquids with lead(II) salts under ionothermal conditions, we have been able to obtain two imidazolium bromoplumbates, (EMIm)PbBr3, I, and (BMIm)2PbBr4, II, where EMIm and BMIm stand for 1-ethyl-3-methyl and 1-butyl-3-methyl imidazolium cations respectively. Interestingly, both these compounds exhibit unusual supramolecular organization wherein dialkylimidazolium cations arrange themselves in a cylindrical fashion giving rise to channel structures. The bromoplumbate anions reside in the channels. The lead(II) cation exhibits either hemi- or holodirected coordination geometry.

Thermodynamic approach for the evaluation of the reactivity of mercaptobenzothiazole reagents with Pb and Zn cations; correlation with results of flotation

The aim of this work is to demonstrate the possibility of forecasting the efficiency and selectivity of chelating reagents in flotation of metallic minerals through a theoretical study of the reactivity of specific chelating reagents towards Zn and Pb cations. The theoretical method is based on calculation of conditional constants. The work reported here is concerned with the thermodynamic calculation of conditional constants of metal–ligand compounds of some mercaptobenzothiazole (MBT) reagents with lead and zinc cations, applied to evaluate the collecting action of MBT reagents on Pb and Zn minerals. From the comparison of the results of thermodynamic calculation with the flotation results previously obtained on oxidised and sulphidised minerals of Pb and Zn, it is evidenced that these reagents are optimum selective collectors of Pb with respect to Zn minerals and that the introduction of a methyl group increases efficacy. Therefore, the calculation results and the hypotheses on which they are based have been confirmed. Infrared and X-ray photoelectron spectroscopy studies have also shown that the formation of surface chelate complexes is responsible for the collecting action of these reagents.

Hybrid structures formed by homo- and heteroleptic aliphatic dicarboxylates of lead with 2-D inorganic connectivity

Three-dimensional homoleptic (single type of ligand) lead dicarboxylates with hybrid structures involving Pb–O–Pb linkages of the compositions, Pb(C 5H 6O 4), I, and Pb(C 6H 8O 4), II and III, have been synthesized and characterized. Three-dimensional heteroleptic (mixed ligands) lead dicarboxylates of the formulae, Pb 2(C 2O 4)(C 4H 4O 4), IV and Pb 2(C 2O 4)(C 6H 8O 4), V, with hybrid structures involving Pb–O–Pb linkages have also been prepared and characterized along with a novel two-dimensional lead nitrate-oxalate of the composition, (OPb 2) 2(C 2O 4)(NO 3) 2, VI. In all these dicarboxylates, there is two-dimensional inorganic connectivity and the lead (II) cation has hemi- or holo-directed coordination geometry. Depending upon the torsional angle and the coordination mode of the dicarboxylate anions as well as the geometry of the lead (II) cations, these hybrid compounds exhibit two types of two-dimensional inorganic connectivities.

Mechanisms of heavy metal sorption on alkaline clays from Tundulu in Malawi as determined by EXAFS

Chromium(III), copper(II), zinc(II), cadmium(II), mercury(II) and lead(II) cations are among the most common heavy metal pollutants in industrial waste waters. In our continued work on cost effective wastewater heavy metal removal agents and methods using local material, this study examines the interactions of chromium(III), copper(II), zinc(II), cadmium(II), mercury(II) and lead(II) cations with natural mixed clay minerals from Tundulu in Malawi using extended X-ray absorption fine structure (EXAFS) spectroscopy. The mixed clays were previously characterised and found to contain illite, low ordered kaolinite, mixed layer minerals and the non-clay mineral carbonate fluoroapatite with a mean pH PZC of 9.63. The EXAFS analyses provided qualitative evidence that oxygen atoms occupy the first coordination shells in all the studied central atoms. The metal species on the clay mineral surfaces seem to be adsorbates and/or precipitates of hydrolysis products. Chromium(III) forms a polynuclear hydrolysis complex on the mineral surface with Cr–O bond and Cr⋯Cr distances of 2.00 and 3.03 Å, respectively, which is indicative of a chain structure with edge sharing CrO 6 octahedra. Copper(II) is bound to phosphate groups on the surface at low pH and has a first shell of coordinated oxygen atoms with Jahn–Teller distortion as revealed by different Cu–O bonds of 1.96 Å for the equatorial ones, at 2.30 and 2.65 Å for the axial oxygens, and a Cu–P distance at 3.29 Å is distinguished as well. Upon treatment at neutral pH copper(I) oxide seems to be the main precipitation product on the clay surface. At neutral pH zinc(II) forms also polynuclear hydrolysis complexes with Zn–O bond and Zn⋯Zn distances of 2.01 and 3.11 Å, respectively, which shows the presence of edge sharing ZnO 4 tetrahedra. Cadmium(II) is adsorbed to the clay surfaces as a six-coordinated CdO 6 complex in octahedral fashion, but it is not possible to distinguish if cadmium is hydrated or partly hydrolysed. Mercury(II) is present as linear O–Hg–O units but without any observable Hg⋯Hg distance at high pH showing that mercury(II) is hydrolysed but not present as mercury(II) oxide. At low pH, linear O–Hg–Hg–O units are present showing that mercury(II) is reduced to mercury(I). No precise chemical environment around the lead(II) could be obtained for the lead(II) treated clays due to formation of different hydrolysis structures with multiple coordination numbers by lead(II) salts on the mixed clays.

Immobilization of Heavy Metals and Phenol on Altered Bituminous Coals

This article evaluates adsorption ability of the altered bituminous coals to remove heavy metals and/or phenol from aqueous solutions. As for heavy metals, copper (II), cadmium (II) and lead (II) cations were used. In addition to phenol, cyclohexanol and 2-cyclohexen-1-ol were also examined. Adsorption experiments were conducted in the batch mode at room temperature and at pH 3 and 5. To characterize the texture of coal samples, adsorption isotherms of nitrogen at −196°C, enthalpies of the immersion in water, and pH values in aqueous dispersions were measured. Coal hydrogen aromaticities were evaluated from the infrared spectrometric examinations (DRIFTS). Based on the investigations performed, cation exchange was confirmed as the principal mechanism to immobilize heavy metallic ions on coals. However, apart from carboxylic groups, other functionalities (hydroxyl groups) were found to be involved in the adsorption process. During adsorption of phenol, π-π interactions between π-electrons of phenol and aromatic rings of coal proved to play the important role; however, no distinct correlation between adsorption capacities for phenol and hydrogen aromaticities of the coal was found. Probable involvement of oxygenated surface groups in the immobilization of phenol on coal was deduced. As a result, for waste water treatment, oxidative altered bituminous coal can be recommended as a suitable precursor, with the largest immobilization capacities both for metallic ions and phenol, as found in the studied samples.

Pectin extraction from pumpkin with the aid of microbial enzymes

An optimised procedure is reported for extraction of pectin from pumpkin pulp, using an enzyme preparation from Aspergillus awamori. In contrast to pumpkin pectin obtained previously by digestion with cell-free culture medium from Bacillus polymyxa, the material prepared in the present work forms gels with 60 wt% sucrose at pH 3, although the yield is somewhat lower (14% in comparison with 22%). The main action of the enzyme complex from A. awamori is to degrade cellulose and other insoluble constituents of the plant tissue, but it also has some pectinesterase activity, which could allow degree of esterification (DE) to be manipulated by varying digestion time. The time used in this investigation (3 h) gave a DE of 53%; reduction in DE at longer times should yield pectin with a higher content of unesterified galacturonate residues, capable of binding lead and other heavy-metal cations. Some possible medicinal and food uses are suggested.

A COMPREHENSIVE APPROACH FOR MODELING SORPTION OF LEAD AND COBALT IONS THROUGH FISH SCALES AS AN ADSORBENT

ABSTRACT Removal of lead and cobalt cations from both industrial and municipal water is of extreme importance for waste water disposal standards. Using fish scales as an adsorbent, 95% of the lead cations and 70% of the cobalt ions can be removed. The processes related to the removal of the cations include adsorption and precipitation. The effect of precipitation of the cations in a neutral medium (pH 7) is studied and is found to be insignificant. Although the effect of precipitation is negligible in the studied experimental runs, it may assume significance in a highly nonporous medium. As sorption dictates the interactions between the bulk and adsorbed phases, it is the most important factor influencing the transport of the chemical species through the medium. Mobility of the cations has extreme importance to overall sorption characteristics because of high adsorption coefficients of the fish scales. It can be further concluded that even at cation concentration levels of 1000 ppm, sorption behavior is insensitive to change. To investigate the nature of the sorption mechanism, a series of experimental runs was conducted using fish scales of the Gadus Morhua (Atlantic cod) and Lethrinus nebulosus (spangled emperor or shouairi) species as substrates. A simulation model based on the theory of surface excess with mechanical entrapment is developed in this study. Numerical simulation results demonstrate reasonable agreements with the experimental results. This study illustrates that variations of flow rates of the cations did have a considerable effect on breakthrough time intervals. An increase in flow rate led to earlier contaminant breakthrough. However, variance of the cation concentrations did not have a dominant effect on the corresponding breakthrough values. The effect of porosity of the adsorbents is observed, and it is determined it has a profound impact on adsorption phenomena. The dispersion parameter is found to be a function of porosity, and its effect was studied in relation to the flow rate of the bulk phase. A decrease in porosity of the adsorbent results in an increase of the retardation factor of the contaminant in bulk phase and an equivalent delay in the breakthrough interval. In order to study the adsorption characteristics by surface excess model, the pH parameter was maintained at a constant pH value of 7 for all the experimental runs. The adsorption coefficient (K) was coupled into the numerical model as a parameter independent of the pH values. The numerical simulations did fit reasonably well with the experimental data. The surface excess theory has been tested in the past only for anionic solutions. The significance of this research is that this model has been applied for the first time with respect to a bio-adsorbent in relation to heavy metal cations. It is found to be suitable for describing adsorption behavior of metallic contaminants at neutral pH. For studying adsorption with respect to the pH variable, a different adsorption model based on, the Langmuir isotherm is proposed.

Structure and lattice dynamics of binary lead silicate glasses investigated by infrared spectroscopy

The polar lattices dynamics of seven binary lead silicate glasses have been studied by infrared spectroscopy. The analysis of the reflectivity spectra with a dielectric function model, based on a modified Gaussian profile, allows a quantitative evaluation of the presence of lead cations within different structural sites. From the role of the lead cations versus the degree of polymerization of the silicate network and the comparison with literature results, we may to give a scenario for explaining the observed structural evolution of the glass matrix and more particularly the drastic change occurring around 45% of lead content. Below this threshold, lead cations act only as modifiers of the silicate network. Above, the glass structure is deeply modified; a lead network involving around 10% of the lead content appears in glasses whose composition is just above the threshold and progressively grows at the expense of the silicate network with the increase of lead content. For high lead content, lead cations can act as modifiers of the silicate network or as network formers. Results also show that the analysis of far infrared measurements combined with the knowledge of the UV edge optical response is very promising to characterize the local disorder around cations in glasses.

Characterization of an unusual folding pattern in a catalytically active guanine quadruplex structure

In the presence of certain metal ions, DNA and RNA can form guanine quadruplex structures, which have been proposed to play a functional role in a variety of biological processes. An 18-nucleotide DNA oligomer, PS2.M, d(GTG3TAG3CG3T2G2), was previously reported to bind hemin and the resulting complex exhibited peroxidase activity. It was proposed that PS2.M folds unimolecularly into an antiparallel quadruplex with unusual, single-base loops and terminal guanines positioned in adjacent quartets. Here we describe structural and stability properties of PS2.M alone in different buffers and metal ions, using gel electrophoresis, circular dichroism (CD), ultraviolet (UV)-visible spectroscopies, and one-dimensional 1H nuclear magnetic resonance (NMR). Native gel behavior of PS2.M in the presence of either Na+ or Pb2+ suggests the formation of unimolecular structures but, in the presence of K+, both unimolecular and multistranded structures are observed. In the presence of Pb2+ ions, PS2.M forms a unimolecular quadruplex containing three guanine quartets. CD titrations reveal that binding of Pb2+ ions to PS2.M is stoichiometric, and a single lead cation suffices to fully fold PS2.M. The PS2.M-Na+ system also forms a similar unimolecular quadruplex. In the presence of K+, the PS2.M-K+ system forms mixed species. With increasing time and PS2.M concentration, the contribution of unimolecular species decreases while that of multimolecular species increases, and this behavior is independent of buffer media. These results suggest that the catalytically active form, studied in the presence of K+, may be a parallel, multistranded quadruplex rather than an antiparallel, unimolecular quadruplex.

Vermiculite as a useful host for guest cyclic aliphatic amine intercalation, followed by cation adsorption

Two vermiculite hybrids containing aliphatic amines intercalated were synthesized. The amount of guest molecules intercalated resulted in 0.60 and 0.52 mmol g −1 for pyperidine and pyperazine, respectively, which reflect the effectiveness of such kind of reactions. The processes were confirmed by elemental analysis and infrared spectroscopy. X-ray diffraction patterns suggested that the original crystallinity of matrix was maintained, however, the intercalation process is associated with the conformation of the guest molecule and the presence of the compensate cation inside the interlayer cavity. The intercalated inorganic hosts adsorb divalent lead, nickel, copper and cobalt cations, more effectively at basic pH value, from aqueous solution, which content of adsorption is higher than the precursor native vermiculite.

Dielectric response near the permittivity maximum in (Sr0.8Pb0.2)TiO3 ceramic solid solution

It is well known that the weak-field relative dielectric permittivity maximum ϵw(max) achieved at the paraelectric-ferroelectric phase transition in ceramic ferroelectric solid solutions in the perovskite structure family is a strong function of the processing conditions used in fabrications. Heretofore, the height and sharpness of the dielectric peak have often been regarded as good qualitative indicators of the quality and homogeneity of the solid solutions. In the SrTiO3–PbTiO3 solid solution system at low PbTiO3 concentrations, this sensitivity is again strongly evident. Now, however, even for samples with a very sharp ϵw(max) giving values &amp;gt;45000 at weak-field dielectric maximum temperature Tmax above the peak temperature, 1∕ϵw (ϵw: weak-field relative dielectric permittivity) departs from Curie-Weiss behavior more than 15°C above the Curie-Weiss temperature θ which now occurs above Tmax. The unusual condition Tmax&amp;lt;θ appears to occur for quite a wide range of processing conditions. Measurements of thermal contraction also show departure from linearity for more than 15°C above θ when measured over the same temperature range, suggesting the development of micro- or nanopolar regions as in a relaxor ferroelectric and this polar character has been confirmed by recent Raman spectroscopy. There is, however, no evidence of dielectric relaxation in the radio-frequency range as in the classic relaxors; however, earlier studies on similar compositions have shown strong dispersion in the gigahertz frequency range at temperatures near to but above Tmax. Preliminary studies of x-ray-diffraction linewidth also suggest that the highest permittivity peak samples are less homogenous, perhaps indicating that micropolarity may be associated with inhomogeneity in the lead cation distribution.

Potentiodynamic electrochemical impedance spectroscopy of lead upd on polycrystalline gold and on selenium atomic underlayer

Pb upd on polycrystalline Au and on Au coated with Se atomic layer was investigated by potentiodynamic electrochemical impedance spectroscopy. Faradaic and double layer responses have disclosed two distinct stages in Pb upd on Au: a partly irreversible stage, attributed to formation and growth of Pb 2D islands, and a reversible phase transition in the final stage of a monolayer deposition. The completion of a continuous monolayer formation in the potential scan was signalised by a sharp minimum in double layer pseudocapacitance Q dl. Pb 2+ reduction, which was monitored concurrently by parameters of Faradaic response, continued shortly after the Q dl minimum and showed sharp maxima of adsorption capacitance and inverse Warburg constant at 40 mV below Q dl minimum. This was explained by surface free energy minimisation that forced continuous atomic layer formation with inclusion of some lead cations into Pb monolayer. The two-stage Pb upd transformed into a single-stage strongly irreversible upd as a result of Se atomic underlayer deposition on Au.

Synthesis, crystal structure and magnetic properties of Fe2Pb3−xBax(PO4)4 (0≤x&lt;3)

Abstract The new solid solution Fe 2 Pb 3− x Ba x (PO 4 ) 4 has been synthesized by the solid reactions. In the whole experimental range (0≤ x T =850 °C), this solid solution is isotypic to the pure phase Fe 2 Pb 3 (PO 4 ) 4 . This compound crystallizes in the monoclinic space group P 2 1 / c , with a =9.0106(6) A, b =9.0632(7) A, c =9.3101(7) A, β =116.867(3)° and Z =2. The structure has been determined from a single crystal and refined to R =0.075. The Fe 2 Pb 3 (PO 4 ) 4 structure can be described as a three-dimensional array containing isolated [Fe 3+ O 6 ] octahedra connected through PO 4 tetrahedra, enclosing a network of cavities where the lead cations reside. Fe 2 Pb 3 (PO 4 ) 4 is antiferromagnetic below T N =30 K; this is consistent with the fact that the main magnetic interactions are Fe–O–P–O–Fe superexchange. The room temperature Mossbauer spectrum exhibits a common place Fe 3+ signal ( δ =0.45 mm/s, Δ =0.32 mm/s). The substitution of the Pb 2+ by Ba 2+ cations increases the cell volume in good agreement with the variation of their ionic radius.