Computer Simulation of Insoluble Pr(III) Speciation in Human Interstitial Fluid

Due to the wide application of rare earths, more and more rare earths enter into environment, and human body via food chain etc1,2. It becomes very urgent to study the biological effect of rare earths. It is well known that biological effects of metal ions depend on their speciation in biological systems. Therefore, the research on rare earth speciation is a key to understand their distribution, metabolism and biological effects. Previous researches were devoted to rare earth speciation in…     

Lanthanum(III) and praseodymium(III) derivatives with dithiocarbamates derived from alpha-amino acids

Lanthanum(III) and praseodymium(III) complexes with dithiocarbamates have been synthesized by the reactions of lanthanum(III) and praseodymium(III) chloride with barium dithiocarbamate and complexes of type [LnCl(L)H2O]n have been obtained (where Ln=La(III) or Pr(III); L=barium salt of dithiocarbamate derived from glycine, L-leucine, L-valine, DL-alanine). The complexes have been characterized by elemental analysis, molar conductance, electronic absorption and fluorescence, infrared, far infrared, 1H NMR spectral studies. The presence of coordinated water molecule is inferred from thermogravimetric analysis which indicates the loss of one water molecule at 150-170 degrees C. The oscillator strength, Judd-Ofelt intensity parameter, stimulated emission cross-section, etc. have been obtained for different transitions of Pr3+.     

Lanthanide complexes of chiral 3 + 3 macrocycles derived from (1R,2R)-1,2-diaminocyclohexane and 2,6-diformyl-4-methylphenol

The enantiopure amine macrocycle H(3)L, as well as the parent macrocyclic Schiff base H(3)L1, the 3 + 3 condensation product of (1R,2R)-1,2-diaminocyclohexane and 2,6-diformyl-4-methylphenol, are able to form mononuclear complexes with lanthanide(III) ions. The lanthanide(III) complexes of H(3)L have been studied in solution using NMR spectroscopy and electrospray mass spectrometry. The NMR spectra indicate the presence of complexes of low C(1) and C(2) symmetry. The (1)H and (13)C NMR signals of the Lu(III) complex obtained from H(3)L have been assigned on the basis of COSY, TOCSY, NOESY, ROESY and HMQC spectra. The NMR data reveal unsymmetrical binding of lanthanide(III) ion and the presence of a dynamic process corresponding to rotation of Lu(III) within the macrocycle. The [Ln(H(4)L)(NO(3))(2)](NO(3))(2)(Ln = Sm(III), Eu(III), Dy(III), Yb(III) and Lu(III)) complexes of the cationic ligand H(4)L(+) have been isolated in pure form. The X-ray analysis of the [Eu(H(4)L)(NO(3))(2)](NO(3))(2) complex confirms the coordination mode of the macrocycle determined on the basis of NMR results. In this complex the europium(III) ion is bound to three phenolate oxygen atoms and two amine nitrogen atoms of the monoprotonated macrocycle H(4)L(+), as well as to two axial bidendate nitrate anions. In the presence of a base, mononuclear La(III), Ce(III) and Pr(III) complexes of the deprotonated form of the ligand L(3-) can be obtained. When 2 equivalents of Pr(III) are used in this synthesis Na(3)[Pr(2)L(NO(3))(2)(OH)(2)](2)NO(3).5H(2)O is obtained. The NMR, ES MS and an X-ray crystal model of this complex show coordination of two Pr(III) ions by the macrocycle L. The X-ray crystal structure of the free macrocycle H(3)L1 has also been determined. In contrast to macrocyclic amine H(3)L, the Schiff base H(3)L1 adopts a cone-type conformation resembling calixarenes.     

Extraction and separation of thorium(IV) and praseodymium (III) with CYANEX 301 and CYANEX 302 from nitrate medium

Solvent extraction of Pr(III) and Th(IV) has been investigated with commercial extractants of CYANEX 301 (bis(2,4,4-trimethylpentyl) dithiophosphinic acid) and CYANEX 302 (bis(2,4,4-trimethylpentyl) monothiophosphinic acid) in kerosene from nitrate medium. The effects of various parameters affecting the extraction equilibrium of Th(IV) and Pr(III), including temperature, were studied and the stoichiometry of the extracted Th(IV) and Pr(III) species was elucidated. The separation of Th(IV) from Pr(III) depending on the difference in the extraction behavior of the two extractants towards these metals is given and discussed.This revised version was published online in November 2005 with corrections to the Cover Date.     

Absorption spectroscopic study of synergistic extraction of praseodymium with benzoyl acetone in presence of crown ether

The extraction behaviour of Pr(III) from aqueous nitric acid medium employing benzoylacetone has been studied in presence of two crown ethers, viz., 15-crown-5 and benzo-15-crown-5 in chloroform medium using UV-vis absorption spectroscopy. The binary equilibrium constant (logk(ex)) for the complex [Pr(benzoylacetonate)(NO3(-))2(H(2)O)] in organic phase was found to be 1.170. The overall equilibrium constants (logK) for the ternary species [Pr(benzoylacetonate)(crown ether)(NO3(-))(2)] were estimated to be 4.01 and 4.41 for 15-crown-5 and benzo-15-crown-5, respectively. The trend in the equilibrium constant values were very much in accordance with the nature of substitution of the donor moiety. The extraction of Pr(III) by the benzoylacetone-crown ether combination was maximum at pH 3.0 and extraction decreases with increase in pH. It has been found that the extent of extraction of Pr(III) in organic phase as the binary as well as ternary complex [Pr(benzoylacetonate)(NO3(-))(2)(H(2)O)] and [Pr(benzoylacetonate)(crown ether)(NO3(-))(2)] increases with increase in concentration of the ligand. Similar trend is observed in the extraction by only donors. Enthalpies and entropies of formation for the ternary extraction process have been estimated. In addition, the effect of NaNO(3) as foreign salt was also studied and it was observed that with increase in ionic strength, percentage extraction increases.     

Fluorescence and DNA-binding properties of neodymium(III) and praseodymium(III) complexes containing 1,10-phenanthroline

The binding of neodymium(III) and praseodymium(III) complexes containing 1,10-phenanthroline, [M(phen)2Cl3·OH2] (M=Nd (1), Pr (2)), to DNA has been investigated by absorption, emission, and viscosity measurements. The complexes show absorption decreasing in charge transfer band, fluorescence decrement when bound to DNA. The binding constant Kb has been determined by absorption measurement for both complexes and found to be (6.76±0.12)×10(4) for 1 and (1.83±0.15)×10(4)M(-1), for 2. The fluorescence of [M(phen)2Cl3·OH2] (M=Nd (1), Pr (2)) has been studied in detail. The results of fluorescence titration reveal that DNA has the strong ability to quenching the intrinsic fluorescence of Nd(III) and Pr(III) complexes through the static quenching procedure. The binding site number n, apparent binding constant Kb and the Stern-Volmer constant kSV are determined. Thermodynamic parameters, enthalpy change (ΔH°) and entropy change (ΔS°), are calculated according to relevant fluorescent data and Van't Hoff equation. The experimental data suggest that the complexes bind to DNA by non-intercalative mode. Major groove binding is the preferred mode of interaction for [M(phen)2Cl3·OH2] (M=Nd (1), Pr (2)) with DNA.     

Preparation and properties of uniform praseodymium-doped ceria colloidal particles

 A procedure to prepare submicrometre spherical particles of Pr(III), Ce(III) or Pr(III)-doped C(III) hydroxycarbonates with narrow size distribution is reported. The particles were obtained by aging aqueous solutions of Pr(III) chloride and/or Ce(III) nitrate in the presence of urea at 100 °C for 2 h. The effect of Pr and/or Ce salt concentrations in the starting solutions on the size, shape and composition of the precipitated particles is reported. The thermal behaviour of the basic carbonates up to decomposition into the metal oxides was followed by differential thermal and thermogravimetric analyses, X-ray diffraction, IR spectroscopy and transmission electron microscopy. All the systems were also characterized by their electrokinetic behaviour (determination of isoelectric point) and specific surface areas. The colour of the powders was also evaluated as a function of the Pr content and temperature and was compared with previous results on red pigments of similar composition. Received: 30 May 2001 Revised: 17 September 2001 Accepted: 20 September 2001     

Hydrated structures and dehydration processes of lanthanoid(III) chloranilates studied by EXAFS

The local structures of lanthanoid(III) chloranilate complexes of Pr(III), Nd(III), Tb(III) and Er(III) have been studied by EXAFS (extended X-ray absorption fine structure). Hydrated structures of the lanthanoid(III) ions in these complexes have been investigated with respect to their coordination numbers and interatomic distances. Six or four water molecules coordinate to the lanthanoid(III) ion of Pr(III) or Nd(III), respectively, just after preparation of the complexes. The temperature dependence of the first coordinated structures has been studied in order to reveal the behavior of the coordinated water molecules in dehydration process. The coordination number around the central lanthanoid(III) ion decreases stepwise as temperature increases, depending on the type of central lanthanoid(III) ion present. The interatomic distance between the central lanthanoid(III) ion and oxygen atoms in the first shell decreases, accompanying the decrease of the coordination numbers. A parameter representing proportion shows the reduction of interatomic distance as one coordinated water molecule removes from the central ion, depending on the type of lanthanoid(III) ions.     

Speciation of Cr(III) and Cr(VI) in environmental samples by using coprecipitation with praseodymium(III) hydroxide and determination by flame atomic absorption spectrometry

A speciation procedure has been established for the flame atomic absorption spectrometric determination of Cr(III) and Cr(VI) based on coprecipitation of Cr(III) by using praseodymium(III) hydroxide (Pr(OH)₃) precipitate. In the presented system, Cr(III) was quantitatively (>95%) recovered at the pH range of 10.0?C12.0 on Pr(III) hydroxide, while the recoveries of Cr(VI) were below 10%. The method was applied to the determination of the total chromium after reduction of Cr(VI) to Cr(III) by using hydroxylamine hydrochloride. The concentration of Cr(VI) is calculated by difference of total chromium and Cr(III) levels. The analytical parameters including pH of the aqueous medium, amount of Pr(III), centrifugation speed, sample volume were optimized. The influences of matrix ions were also investigated. The method was validated by the analysis of TMDA 70 fortified lake water certified reference material. The method was applied to the speciation of chromium in water samples.     

Application of Novel Praseodymium (III) PVC‐Membrane Electrode for Determination of Pr(III) Ions in Soil and Sediment Samples

Abstract

A novel Pr(III) ion‐selective polyvinyl chloride (PVC) membrane sensor, based on N,N‐bis(α‐methylsalicylidene)diethylenetriamine (BMT) as a new ionophore, has been prepared and studied. The electrode showed good selectivity for Pr(III) ion with respect to most common cations, including alkali, alkaline earth, transition, and heavy metal ions. This electrode has a wide linear dynamic range from 1.0×10^?6 to 1.0×10^?2 M with a Nernstian slope of 19.8±0.2 mV per decade and a low detection limit of 6.5×10^?7 M, in the pH range of 3.0–8.4, while response time was rapid (<15 s). As far as applications of the recommended sensor are concerned, first it was employed as an indicator electrode in the potentiometric titration of Pr(III) ions with EDTA. Second, it was effectively applied to the determination of concentration of Pr(III) ions in soil and sediment samples, and validation with CRMs.     

Variation of far order in aqueous solutions of lanthanides trichlorides as function of concentration

X-ray diffraction studies of aqueous solutions of La(III), Pr(III), Nd(III), Sm(III), Gd(III), Dy(III), Er(III), and Lu(III) chlorides have been carried out in a wide range of concentrations. The small-angle maxima at the experimental scattering functions have been assigned; it has been shown that a far order exists in all the studied systems. The changes of scattering functions are discussed; average distances of particles interaction have been estimated. It has been shown that the structure of the concentrated solutions differs significantly from that of the diluted solutions.     

Synthesis,spectral characterization,crystal structures of lanthanide(III) pyrrolidine dithiocarbamate complexes and their catalytic activity

A series of lanthanide(III) pyrrolidine dithiocarbamate complexes [Ln(Pyrrol-Dtc)₃(Phen)] {Pyrrol-Dtc = pyrrolidine dithiocarbamate; Phen = 1,10-phenanthroline; Ln = La(III), Ce(III), Pr(III), Nd(III), Sm(III), Gd(III), Tb(III), Dy(III), Er(III)} have been synthesized and structurally characterized. The molecular structures of [La(Pyrrol-Dtc)₃(Phen)], [Pr(Pyrrol-Dtc)₃(Phen)], [Sm(Pyrrol-Dtc)₃(Phen)], and [Dy(Pyrrol-Dtc)₃(Phen)] have been confirmed using single crystal XRD studies. The results reveal that in these complexes, the central Ln(III) ion is coordinated to three Pyrrol-Dtc and one Phen and possesses a distorted dodecahedron geometry. Catalytic activity of these complexes in trimethylsilylcyanation reaction has been studied.     

Spectrophotometric Study of the Complexation of Some Lanthanide (III) Ions with a Series of 18-Crowns-6 in DMSO Solution Using Murexide as a Metallochromic Indicator

The complexation of La(III), Ce(III), Pr(III) and Er(III) with 18-crown-6(18C6), dibenzo-18-crown-6 (DB18C6), dicyclohexano-18-crown-6 (DCY18C6) anddibenzopyridino-18-crown-6 (DBPY18C6) has been studied in dimethylsulfoxide(DMSO) by means of a competitive spectrophotometric method using murexide asa metal ion indicator. The formation constants of the 1 : 1 complexeswere found tovary in the order La(III) > Ce(III) > Pr(III) > Er(III). It was foundthat the structure influences the formation and stability of the resultingcomplexes. The effects ofvarious parameters on complexation are discussed. The order of the stabilityconstants of each lanthanide ion with these macrocycles are18C6 > DC18C6 > DB18C6 > DBPY18C6.     

A family of 13 tetranuclear zinc(II)-lanthanide(III) complexes of a [3+3] Schiff-base macrocycle derived from 1,4-diformyl-2,3-dihydroxybenzene

A family of thirteen tetranuclear heterometallic zinc(II)-lanthanide(III) complexes of the hexa-imine macrocycle (L(Pr))(6-), with general formula Zn(II)(3)Ln(III)(L(Pr))(NO(3))(3)·xsolvents (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm or Yb), were prepared in a one-pot synthesis using a 3:1:3:3 reaction of zinc(II) acetate, the appropriate lanthanide(III) nitrate, the dialdehyde 1,4-diformyl-2,3-dihydroxybenzene (H(2)L(1)) and 1,3-diaminopropane. A hexanuclear homometallic zinc(II) macrocyclic complex [Zn(6)(L(Pr))(OAc)(5)(OH)(H(2)O)]·3H(2)O was obtained using a 2:0:1:1 ratio of the same reagents. A control experiment using a 1:0:1:1 ratio failed to generate the lanthanide-free [Zn(3)(L(Pr))] macrocyclic complex. The reaction of H(2)L(1) and zinc(II) acetate in a 1:1 ratio yielded the pentanuclear homometallic complex of the dialdehyde H(2)L(1), [Zn(5)(L(1))(5)(H(2)O)(6)]·3H(2)O. An X-ray crystal structure determination revealed [Zn(3)(II)Pr(III)(L(Pr))(NO(3))(2)(DMF)(3)](NO(3))·0.9DMF has the large ten-coordinate lanthanide(III) ion bound in the central O(6) site with two bidentate nitrate anions completing the O(10) coordination sphere. The three square pyramidal zinc(II) ions are in the outer N(2)O(2) sites with a fifth donor from DMF. Measurement of the magnetic properties of [Zn(II)(3)Dy(III)(L(Pr))(NO(3))(3)(MeOH)(3)]·4H(2)O with a weak external dc field showed that it has a frequency-dependent out-of-phase component of ac susceptibility, indicative of slow relaxation of the magnetization (SMM behaviour). Likewise, the Er and Yb analogues are field-induced SMMs; the latter is only the second example of a Yb-based SMM. The neodymium, ytterbium and erbium complexes are luminescent in the solid phase, but only the ytterbium and neodymium complexes show strong lanthanide-centred luminescence in DMF solution.     

Solvent extraction of trivalent lanthanide Pr(III), Ho(III) and Er(III) with N-benzoyl-N-phenylhydroxylamine

Extraction of Pr(III), Ho(III) and Er(III) has been studied in the pH range of 1–10 with N-benzoyl-N-phenylhydroxylamine (BPHA) in benzene. The separation was found to be quantitative in borate media from pH 7 to 10, at an ionic strength of 0.1M (H⁺, BO₃ ^3–). The stoichiometric composition of the complexes under the optimal conditions of shaking time, pH and reagent concentration was formulated using slope analysis and found to be M(BPHA)₃, where M=Pr(III), Ho(III) and Er(III). The effect of various masking agents shows that citrate, ascorbate, EDTA, oxalate, fluoride and phosphate form stable complexes with these rare earths as compared to BPHA. The decontamination factors for different cations with respect to these rare earths under the optimum conditions have been evaluated.     

Chelation behaviour of lanthanons witho-arsonodibenzoylmethanephenylhydrazone

Summary The chelate formation reaction of La(III), Pr(III), Nd(III), Gd(III), Ho(III), and Er(III) witho-arsonodibenzoylmethanephenylhydrazone has been investigated potentiometrically and conductometrically in 40% (v/v) aqueous ethanol, ionic strength 0.1M. The order of stability constants was found to be La < Pr < Nd > Gd < Ho < Er. The chelates formed have 1:1 and 1:2 stoichiometries (M ³⁺:L). The complexes have been isolated in solid state and have been characterized on the basis of elemental analysis and IR data. Coordination occurs through -NH of the hydrazo and-OH of the arsonic groups.

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Chelierungsverhalten von Lanthaniden mito-Arsonodibenzoylmethanphenylhydrazon

Zusammenfassung Die Reaktion der Chelatbildung von La(III), Pr(III), Nd(III), Gd(III), Ho(III) und Er(III) mito-Arsonodibenzoylmethanphenylhydrazon wurde potentiometrisch und konduktometrisch in 40% (v/v) wäßrigem Ethanol bei einer Ionenstärke von 0.1M untersucht. Die Reihung der Stabilitätskonstanten war La < Pr < Nd > Gd < Ho < Er. Die Chelate haben 1:1 und 1:2 Stöchiometrien (M ³⁺:L). Die Komplexe wurden im Festzustand isoliert und mittels Elementaranalyse und IR-Spektroskopie charakterisiert. Die Koordinierung erfolgt über -NH der Hydrazo- und -OH der Arsongruppe.

     

Lanthanide complexes of the heterochiral nonaaza macrocycle: switching the orientation of the helix axis

The La(III), Ce(III), Pr(III), Nd(III), Sm(III), and Eu(III) complexes of the racemic heterochiral nonaaza macrocyclic amine L have been synthesized and characterized by spectroscopic methods. The X-ray crystal structures of the [PrL][Pr(NO(3))(6)].CH(3)OH and the isomorphic [NdL][Nd(NO(3))(6)].CH(3)OH complexes show that all nine nitrogen atoms of the macrocycle coordinate to the Ln(3+) ion, completing its coordination sphere. The macrocycle wraps tightly around the metal ion in double-helical fashion. The structures reveal the RRRRSS/SSSSRR configuration at the stereogenic carbon atoms of the three cyclohexane rings, confirming the heterochiral nature of the parent 3 + 3 macrocycle obtained in the condensation of racemic trans-1,2-diaminocyclohexane and 2,6-diformylpyridine. The NMR spectra of the isolated complexes indicate the presence of low C(1) symmetry [LnL](3+) complexes. The same symmetry is indicated by the X-ray crystal structures of Pr(III) and Nd(III) complexes, which show that for the RRRRSS enantiomer of the macrocycle L, the helix axis passes through the cyclohexane ring of RR chirality and the opposite pyridine ring. The NMR studies of complex formation in solution by the paramagnetic Pr(3+) and Eu(3+) ions indicate that the initially formed [LnL](3+) complexes are of C(2) symmetry. For the RRRRSS enantiomer of the macrocycle L in the C(2)-symmetric species, the helix axis passes through the cyclohexane ring of SS chirality and the opposite pyridine ring. The C(1)-symmetric and C(2)-symmetric forms of the [LnL](3+) complexes constitute a new kind of isomers and the conversion of the kinetic complexation product of C(2) symmetry into the thermodynamic product of C(1) symmetry corresponds to an unprecedented switching of the orientation of the helix axis within the macrocycle framework.     

Separation of Rare-Earth Elements from Nitrate Solutions by Solvent Extraction Using Mixtures of Methyltri-n-octylammonium Nitrate and Tri-n-butyl Phosphate

The article presents data on the solvent extraction separation of rare-earth elements (REEs), such as La(III), Ce(III), Pr(III), and Nd(III), using synergic mixtures of methyltrioctylammonium nitrate (TOMANO₃) with tri-n-butyl phosphate (TBP) from weakly acidic nitrate solutions. Specifically, experimental results on separation of REEs, for the pair Ce(III)/Pr(III) for quaternary mixtures of REEs (La(III), Ce(III), Pr(III), Nd(III)) and for the pair La(III)/Pr(III) for solutions containing La(III), Pr(III), and Nd(III), are presented. It was shown that effective separation for the pair Ce(III)/Pr(III) from a solution containing 219 g Ce(III)/L, 106 g La(III)/L, 20 g Pr(III)/L, 55 g Nd(III)/L, and 0.1 mol/L HNO₃, was achieved using 56 steps of a multistage, counter-current solvent extraction cascade with scrubbing, at an organic-to-aqueous phase volume ratio (O/A) equal to 2/1 on the extraction section and O/A equal to 4/1 on the scrubbing section, using 3.3 mol/L solutions of the mixture TOMANO₃-TBP with molar ratio 0.15:0.85 in dodecane. Separation for the pair La(III)/Pr(III) could be achieved using a solvent extraction cascade with scrubbing in 32 steps at O/A equal to 2/1 on the extraction section and O/A equal to 2.8/1 on the scrubbing section of the solvent extraction cascade from a solution containing 258 g La(III)/L, 58 g Pr(III)/L, 141 g Nd(III)/L, and 0.1 mol/L HNO₃ with 3.0 mol/L solution of the mixture TOMANO₃-TBP with molar ratio 0.2:0.8 in dodecane.     

Determination of neptunium using high resolution sequential ICP-AES

In view to separate La(III), Pr(III) and U(VI) ions, from aqueous solutions, batch experiments are carried out for the sorption and desorption of these ions onto and from a novel functionalized resin. The sorption capacities varied from 1.06 to 47.30 mg/g and increased in the following order La(III), Pr(III) and U(VI), while yields desorption ranged from 73.0 to 94.3% and increased in the following order Pr(III), La(III) and U(VI). Considering the largest difference in sorption capacity and desorption yield of these three elements, at different operates conditions, this material can be potential candidate for the separation of U(VI), Pr(III) and La(III) ions from nuclear and other industrial wastewater.     

Praseodymium(III)-substituted bismuth titanate thin-film generation using metallo-organic precursors with an M-O-C skeleton and sol-gel technique and employing 4f-4f transition spectra as a probe to explore kinetic performance

A hetero-trimetallic lanthanide-substituted bismuth titanate (BLT, where lanthanide is praseodymium) with stoichiometry Pr(0.75)Bi(3.25) Ti(3)O(12) has been obtained as both highly homogenized crystalline and amorphous thin films using three different BLT precursors: (i). precursor A-(Pr(OC(3)H(7)(i))(3),Bi(OOCCH(3))(3),Ti(OC(3)H(7)(i))(4)); (ii). precursor B-(Pr(OC(3)H(7)(i))(2)(acac),Bi(OOCCH(3))(3),Ti(OC(3)H(7)(i))(3)(acac)); and (iii). precursor C-(Pr(OC(3)H(7)(i))(2)(acac),Bi(OOCCH(3))(3),Ti(OC(3)H(7)(i))(2)(acac))(2). These three BLT precursors (A, B, C) are prepared by reacting constituent monometallic precursors in the desired stoichiometry and by employing controlled acidic hydrolysis via the sol-gel method. Paramagnetic Pr(III), being a f(2) ion, gives characteristic 4f-4f transition bands (3H(4)-->3P(2), 3H(4)-->3P(1), 3H(4)-->3P(0), and 3H(4)-->1D(2)) in the visible region, the intensities of which have been found to be highly sensitive to even minor changes in the immediate coordination around Pr(III), occurring as a result of the progress of polycondensation reactions of three multicomponent BLT sols. We have used the changes with time in the intensities (represented by oscillator strengths of these four 4f-4f bands) and the magnitude and variation of the spectral parameters evaluated from the observed spectra with a view toward monitoring the sol-gel reactions of BLT precursors A, B, and C. 4f-4f transition spectra of the aliquots, withdrawn from the hydrolyzing A, B, and C sols at different time intervals, represent the changes occurring in the Pr(III) environment with the progress of sol-gel hydrolysis of BLT, and are used to investigate the kinetic performance in hydrolysis of the three precursors. Kinetics of hydrolysis of precursors A, B, and C indicate that all four f-f transition bands of Pr are almost equally sensitive to precursor hydrolysis in the order A>B>C.