Light Trivalent Lanthanides Research Articles

Efficient Separation of Light Lanthanides(III) by Using Bis-Lactam Phenanthroline Ligands.

Due to the ever-increasing demand for high-purity individual rare-earth elements, novel and highly selective separation processes are increasingly sought after. Herein, we report a separation protocol that employs shape-persistent 2,9-bis-lactam-1,10-phenanthroline (BLPhen) ligands exhibiting unparalleled selectivity for light trivalent lanthanides. The highly preorganised binding pockets of the ligands allowed for the separation of lanthanides with high fidelity, even in the presence of competing transition metals, in a biphasic separation system. Notably, the selectivity trends of the BLPhen ligands towards metal ions across the lanthanide series can be chemically modulated by altering the molecular rigidity of the extractant.

Thermal analysis (TG–DSC, DSC–microscopy and EGA) and characterization of heavy trivalent lanthanides and yttrium isonicotinates

The trivalent lanthanide isonicotinates were synthesized to obtain stoichiometry Lu(IN)3 and Ln(IN)3·2H2O (Ln = Tb to Lu, and Y; IN = isonicotinate). A deep study of the thermal behavior in oxidant (air) and inert (N2) atmospheres was carried out using the following thermoanalytical techniques: simultaneous thermogravimetry and differential scanning calorimetry (TG–DSC), differential scanning calorimetry (DSC) and evolved gas analysis (EGA by TG–DSC–FTIR). From these results, it was possible to determine that dehydration occurs in a single step and the thermal decomposition of the anhydrous compounds occurs in one or two (air), and two or three steps (N2). The final residues of thermal decomposition were Tb4O7 and Ln2O3 (Ln = Dy to Lu, and Y) in air atmosphere, while in N2 atmosphere the mass loss is still being observed up to 1000 °C. The identified gaseous products evolved during the thermal decomposition in dynamic dry air and nitrogen atmospheres were water, CO2, pyridine and CO. From these thermoanalytical data, it was possible to propose a general equation of thermal decomposition of these compounds in the N2 atmosphere. DSC curves of Tb and Ho compounds presented endothermic peaks corresponding to a reversible phase transition, confirmed by powder X-ray diffractometry (XRD), not previously reported. In addition, infrared vibrational spectroscopy (IR) suggests the coordination through carboxylate as bridging bidentate ligand toward the heavy trivalent lanthanides metals. This paper is complementary to our previous study involving the series of light trivalent lanthanides isonicotinates.

Synthesis, thermal behavior, and spectroscopic study of the solid nalidixate of selected light trivalent lanthanides

Solid-state [Ln(nal)3]·nH2O compounds, where Ln represents light trivalent lanthanide (La to Sm, except Pm), nal is nalidixate (C12H11N2O3), and n is the number of water molecules, were synthesized. Characterization and investigation were made by means of complexometry, elemental analysis, powder X-ray diffraction, Fourier transform infrared, near infrared (NIR) and diffuse reflectance spectroscopies, simultaneous thermogravimetry and differential thermal analysis, and differential scanning calorimetry. The dehydration process occurs in a single step up to 453 K. The final temperature of dehydration decreases from Pr(III) to Sm(III), and the thermal stability of anhydrous compounds increases from La(III) to Sm(III) (except Ce), and these behaviors are related to the decrease in the ionic radius of the lanthanide ion. The thermal decomposition of the anhydrous compounds occurs in three, four, or five consecutive steps, with formation of the respective oxides CeO2, Pr6O11, and Ln2O3 (Ln = La, Nd, and Sm) as final residues. The results also provide information concerning the composition and thermal behavior of these compounds. Spectroscopic studies in the UV–Vis and NIR regions provide information about the characteristics 4f–4f transitions for the Pr(III), Nd(III), and Sm(III) compounds, as well as the NIR region characteristic overtone and combination bands of the compounds.

A comparative study on thermal behavior of solid-state light trivalent lanthanide isonicotinates in dynamic dry air and nitrogen atmospheres

Characterization, thermal stability, and thermal decomposition of light trivalent lanthanide isonicotinates Ln(L)3·2H2O (Ln = La to Gd, except Pm; L = isonicotinate) were investigated employing simultaneous thermogravimetry and differential scanning calorimetry (TG–DSC), DSC, infrared spectroscopy (FTIR), evolved gas analysis by TG–DSC coupled to FTIR, elemental analysis, and complexometry. The dehydration of these compounds occurs in a single step, and the thermal decomposition of the anhydrous compounds occurs in one or two (air) and two or three steps (N2). The final residues of thermal decomposition were CeO2, Pr6O11, and Ln2O3 (Ln = La, Nd to Gd) in air atmosphere, while in N2 atmosphere the mass loss is still being observed up to 1000 °C. The results also provided information concerning the gaseous products evolved during the thermal decomposition in dynamic dry air and nitrogen atmospheres.

Thermal behavior, spectroscopic study and evolved gas analysis (EGA) during pyrolysis of picolinic acid, sodium picolinate and its light trivalent lanthanide complexes in solid state

Synthesis, characterization, and thermal behavior of light trivalent lanthanide picolinate (La–Gd, except Pm) as well as the thermal behavior of picolinic acid and its sodium salt were investigated employing elemental analysis, complexometry, differential scanning calorimetry (DSC), simultaneous thermogravimetry and differential scanning calorimetry (TG-DSC), infrared spectroscopy (FTIR), X-ray power diffractometry, and evolved gas analysis (EGA) for TG-DSC coupled to FTIR. All the synthesized compounds were obtained in the anhydrous state and the thermal decomposition in dynamic dry air atmosphere occured in a single step or two consecutive steps with formation of the respective oxides, CeO2, Pr6O11 and Ln2O3 (Ln=La, Nd to Gd). In dynamic dry nitrogen atmosphere the thermal decomposition occured in two or three consecutive steps and mass loss was observed up to 1000°C. The EGA data allowed the identification of gaseous products evolved during pyrolysis and oxidative decomposition. The results of density functional theory (DFT) and FTIR also provided information on the ligand’s denticity.

Synthesis, evolved gas analysis (EGA) during pyrolysis and spectroscopic study of light lanthanide nicotinate in solid state

Solid-state Ln(C9H5NO2)3·2H2O, where Ln stands for light trivalent lanthanides (La to Gd, except Pm) and C9H5NO2 is nicotinate, were synthesized. The methods of simultaneous thermogravimetry and differential scanning calorimetry (TG–DSC), elemental analysis, and complexometry were used to establish the stoichiometry and evolved gas analysis (EGA) for TG–DSC coupled to Fourier transform infrared spectroscopy (FTIR) in order to study the thermal behavior of these compounds in CO2 and N2 atmospheres. The use of density functional theory (DFT) and FTIR were performed in order to propose the structure and the type of existing coordination of the synthesized compounds. All the compounds were obtained in a dehydrated form, and in both the atmospheres dehydration occurred in two consecutive stages, with losses of 1.5 and 0.5 H2O respectively. The final residues of thermal decomposition in CO2 atmosphere were: CeO2 and Ln2O3 (Ln=La, Pr, Nd, Sm, Eu, Gd). In N2 atmosphere, the mass losses were still being observed up to 1000°C for all the compounds.

Synthesis, thermal and spectroscopic study of light lanthanide nicotinate, in the solid state

Abstract Characterization, thermal stability and thermal decomposition of light trivalent lanthanide nicotinates, Ln(C 6 H 4 NO 2 ) 3 ·nH 2 O (Ln = La to Gd, except Pm) were synthesized and investigated employing simultaneous thermogravimetry and differential scanning calorimetry (TG–DSC), Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry, complexometry and TG–DSC coupled to FTIR. In all the compounds the dehydration occurs in two consecutive steps and the thermal decomposition of the anhydrous compounds occurs in single, two, three or four consecutive steps, with the formation of the respective oxides CeO 2 , Pr 6 O 11 and Ln 2 O 3 (Ln = La, Nd, Sm, Eu, Gd), as final residue. The results also provided information about the composition, thermal behavior, identification of gaseous products evolved during the thermal decomposition of these compounds. Furthermore, the theoretical and experimental spectroscopic data suggest the possible modes of coordination of the ligand with the metals.

Synthesis, Characterization and Thermal Behavior of Solid-State Compounds of Light Trivalent Lanthanide Malonates

In this study, compounds of hydrated lanthanide malonates were synthesized by precipitation of sodium malonates ion. Quantitative studies of the compounds obtained in the solid state, as well as the thermal behavior of these compounds were performed by thermal analysis (TG-DTA and DSC). Additional complementary studies were also performed using X-ray diffraction by the powder method (XRD), Evolved Gas Analysis (EGA) and complexometric titration with EDTA. Thus, the compounds synthesized in this work, ranging from lanthanum to gadolinium, were studied mainly in relation to their thermal properties, enabling to establish the stoichiometry, the decomposition steps and identify by EGA the main volatile products released during the decomposition. The qualitative study by XRD and FT-IR showed that the compounds were obtained in the crystalline state and metal-ligand coordination occurs by bidentate bonding and /or bridge, respectively. The interest in these compounds is due to the several applications of malonate ion, such as industrial and biological, not to mention that the coordination of the lanthanide ions to the malonate ligand can provide them new properties which could be studied and explored forward.

Synthesis, characterization, thermal and spectroscopic studies of solid glycolate of light trivalent lanthanides, except promethium

Abstract Solid-state Ln–L compounds, where Ln stands for light trivalent lanthanide (La to Gd, except Pm) and L is glycolate (C2H3O3) have been synthesized. Characterization and investigation were made by means of complexometry, X-ray diffractometry, Fourier transform infrared spectroscopy (FTIR), simultaneous thermogravimetry and differential scanning calorimetry (TG–DSC), and TG–DSC coupled to FTIR. All the compounds were obtained in the anhydrous state. The thermal decomposition of the anhydrous compounds occurs in a single, three, four or five steps and the final residue was CeO2, Pr6O11 and Ln2O3 (Ln = La, Nd to Gd). The results also provide information concerning thermal behavior and identifications of the gaseous products evolved during the thermal decomposition of these compounds. Furthermore, the theoretical and experimental spectroscopic data suggest the possible modes of coordination of the ligand with the metals.

Thermal and spectroscopic studies of solid oxamate of light trivalent lanthanides

Solid-state LnL3·1.25H2O compounds, where L is oxamate and Ln is light trivalent lanthanides, have been synthesized. Simultaneous thermogravimetry and differential scanning calorimetry (TG–DSC), experimental and theoretical infrared spectroscopy, TG–DSC coupled to FTIR, elemental analysis, complexometry, and X-ray powder diffractometry were used to characterize and to study the thermal behavior of these compounds. The results led to information about the composition, dehydration, thermal stability, thermal decomposition, and gaseous products evolved during the thermal decomposition of these compounds in dynamic air atmosphere. The dehydration occurs in a single step and through a slow process. The thermal decomposition of the anhydrous compounds occur in a single (Ce), two (Pr), and three (La, Nd to Gd) steps with the formation of the respective oxides, CeO2, Pr6O11, and Ln2O3 (Ln = La, Nd to Gd). The theoretical and experimental spectroscopic study suggests that the carboxylate group and amide carbonyl group of oxamate are coordinate to the metals in a bidentate chelating mode.

Synthesis, thermal properties and spectroscopic study of solid mandelate of light trivalent lanthanides

Characterization, thermal stability and thermal decomposition of light trivalent lanthanide mandelates Ln(C6H5CH(OH)CO2)3·nH2O (Ln = La to Gd, except Pm) were investigated employing simultaneous thermogravimetry and differential thermal analysis (TG–DTA), differential scanning calorimetry (DSC), experimental and theoretical infrared spectroscopy, elemental analysis, X-ray diffractometry, complexometry and TG–DSC coupled to FTIR. The dehydration of the lanthanum, samarium, europium and gadolinium compounds occurs in a single step while for praseodymium and neodymium ones it occurs in two consecutive steps. The thermal decomposition of the anhydrous compounds occurs in three, four or five consecutive steps, with formation of the respective oxides CeO2, Pr6O11 and Ln2O3 (Ln = La, Nd to Gd) as final residues. The results also provide information concerning the composition, thermal behavior and gaseous products evolved during the thermal decomposition of these compounds. The theoretical and experimental spectroscopic data suggest the possible modes of coordination of the ligand with the lanthanum.

Thermal behaviour of fumaric acid, sodium fumarate and its compounds with light trivalent lanthanides in air atmosphere

Abstract Characterization, thermal stability and thermal decomposition of light trivalent lanthanide fumarates, as well as, the thermal behaviour of fumaric acid and its sodium salt were investigated employing simultaneous thermogravimetry and differential thermal analysis, differential scanning calorimetry, Fourier transform infrared spectroscopy (FTIR), TG–FTIR techniques, elemental analysis and complexometry. On heating, sublimation of fumaric acid is observed, while the thermal decomposition of the sodium fumarate occurs with the formation of a mixture of sodium carbonate and carbonaceous residue. The thermal decomposition of light trivalent lanthanide fumarates occurs in consecutive and/or overlapping steps with the formation of the respective oxides: CeO2, Pr6O11, and Ln2O3 (Ln = La, Nd, Sm, Eu, Gd).

Synthesis, characterization and thermal behaviour of light trivalent lanthanides folates on solid state

Solid state Ln2-L3 compounds, where Ln stands for light trivalent lanthanides (lanthanum to gado- linium), except promethium, and L is folate (C19H17N7O6), have been synthesized. Simultaneous thermogravimetry and differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC), X-ray powder diffractometry, infrared spectroscopy (FTIR), TG coupled to FTIR, ele- mental analysis and complexometry were used to charac- terize and to study the thermal behaviour of these compounds. The results provided information concerning the stoichiometry, crystallinity, ligand's denticity, thermal stability, thermal behaviour and identification of the gaseous products evolved during the thermal decomposition of these compounds.

Synthesis, characterization and thermal behaviour of solid-state compounds of light trivalent lanthanide succinates

Characterization, thermal stability and thermal decomposition of light trivalent lanthanide succinates, Ln 2(C 4H 4O 4) 3· nH 2O (Ln = La to Gd, except Pm) were investigated employing simultaneous thermogravimetry and differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC), infrared spectroscopy, TG-FTIR system, elemental analysis and complexometry. The dehydration of the lanthanum and cerium compounds occurs in a single step, while for the praseodymium to gadolinium compounds the dehydration occurs in two consecutive steps. The thermal decomposition of the anhydrous compounds occurs in consecutive and/or overlapping steps, except for the cerium compound, with formation of the respective oxides, CeO 2, Pr 6O 11 and Ln 2O 3 (Ln = La, Nd to Gd), as final residue. The results also provided information concerning the denticity of the ligand and thermal behaviour of these compounds.

Synthesis, characterization and thermal behavior on solid tartrates of light trivalent lanthanides

Solid state Ln–L compounds, where Ln stands for light trivalent lanthanides (L–Gd) and L is tartrate, have been synthesized. Thermogravimetry and differential thermal analysis (TG/DTA), differential scanning calorimetry (DSC), X-ray powder diffractometry, elemental analysis and complexometry were used to characterize and to study the thermal behaviour of these compounds. The results led to information about the composition, dehydration and thermal decomposition of the isolated compounds.

Synthesis, characterization and thermal behaviour of solid 2-methoxycinnamylidenepyruvate of light trivalent lanthanides

Solid state Ln-2-MeO-CP compounds, where Ln stands for light trivalent lanthanides (La, Ce, Pr, Nd, Sm, Eu, Gd) and 2-MeO-CP is 2-methoxycinnamylidenepyruvate, were synthesized in this work. Simultaneous thermogravimetry and differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC), X-ray powder diffractometry, experimental and theoretical infrared spectroscopy and complexometry were used to characterize and to study the thermal behaviour of these compounds. The results led to information regarding the composition and stability of the isolated complexes.

Solid-state 2-methoxybenzoates of light trivalent lanthanides

Solid-state LnL3 compounds, where L is 2-methoxybenzoate and Ln is light trivalent lanthanides, have been synthesized. Thermogravimetry (TG), differential scanning calorimetry (DSC), X-ray powder diffractometry, infrared spectroscopy and elementary analysis were used to characterize and to study the thermal behaviour of these compounds. The results led to information on the composition, dehydration, thermal stability and thermal decomposition of the isolated compounds. On heating these complexes decompose in three (Ce, Pr) or five (La, Nd, Sm) steps with the formation of the respective oxide: CeO2, Pr6O11 and Ln2O3 (Ln=La, Nd, Sm) as final residues. The theoretical and experimental spectroscopic study suggests predominantly the ionic bond between the ligand and metallic center.

Synthesis, characterization and thermal behaviour on solid pyruvates of light trivalent lanthanides

Solid State Ln-L compounds, where Ln stands for light trivalent lanthanides(La – Gd) and L is pyruvate, have been synthesized. Thermogravimetry and derivative thermo-gravimetry (TG/DTG), differential scanning calorimetry (DSC), X-Ray powder diffractometry,infrared spectroscopy, elemental analysis, and complexometry were used to characterize and to studythe thermal behaviour of these compounds. The results led to information about the composition, dehy-dration, ligand denticity, thermal behaviour and thermal decomposition of the isolated compounds.

Microscopic Analysis of 5d States Splitting and Charge Transfer Energies Dependence on Interionic Distance in Alkaline Earth Fluorides Doped with Light Trivalent Lanthanides

A first principles fully relativistic analysis (K. Ogasawara et al., Phys. Rev. B 2001, 64, 115413) of the dependence of 5d orbitals splitting (10Dq) and charge transfer (CT) energies on interionic distance has been performed for light lanthanides (Ce3+, Pr3+, Nd3+) in CaF2, SrF2, BaF2 crystals. The salient feature of the method is that four‐component molecular orbitals (MO) composed of atomic wave functions are used as the basis set. Without any fitting parameter, the power dependencies for 10Dq and linear dependencies for the CT energies on the distance between rare‐earth (RE) ions and ligands were obtained. A comparison with experimental values is discussed.

Synthesis, characterization and thermal behaviour on solid pyruvates of light trivalent lanthanides

Solid State Ln-L compounds, where Ln stands for light trivalent lanthanides (La - Gd) and L is pyruvate, have been synthesized. Thermogravimetry and derivative thermogravimetry (TG/DTG), differential scanning calorimetry (DSC), X-Ray powder diffractometry, infrared spectroscopy, elemental analysis, and complexometry were used to characterize and to study the thermal behaviour of these compounds. The results led to information about the composition, dehydration, ligand denticity, thermal behaviour and thermal decomposition of the isolated compounds.