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Barium yttrium phosphate (BYP) phosphor doped with trivalent praseodymium ions (BaY(1-x) (PO4 )3 :Pr3+ (x = 0, 0.01, 0.05, 0.1, 0.15, and 0.2 wt%) was synthesized using a high temperature solid-state reaction method. Structural properties were analyzed through X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. XRD patterns confirmed the structure of the synthesized phosphor and average crystalline size was estimated (approximately 63.8 A). Vibrational functional groups were identified using FTIR spectroscopy. The emission spectrum was recorded under an 444 nm excitation wavelength, which showed various emission transitions of Pr3+ ions. Commission Internationale de l'eclairage coordinates, colour purity, and colour correlated temperature values were calculated for the BYP:Pr3+ phosphors and these coordinate values fell in the yellow region of the visible spectrum.

Targeting the synthesis of rare-earth-metal pentadienyl half-sandwich tetramethylaluminate complexes, homoleptic [Ln(AlMe4 )3 ] (Ln=Y, La, Ce, Pr, Nd, Lu) were treated with equimolar amounts of the potassium salts K(2,4-dmp) (2,4-dmp=2,4-dimethylpentadienyl), K(2,4-dipp) (2,4-dipp=2,4-diisopropylpentadienyl), and K(2,4-dtbp) (2,4-dtbp=2,4-di-tert-butylpentadienyl). The reactions involving the larger rare-earth-metal centers lanthanum, cerium, praseodymium, and neodymium gave selectively the desired half-sandwich complexes [(2,4-dmp)La(AlMe4 )2 ], [(2,4-dipp)La(AlMe4 )2 ], and [(2,4-dtbp)Ln(AlMe4 )2 ] (Ln=La, Ce, Pr, Nd) in high crystalline yields. Smaller rare-earth-metal centers yielded preferentially the sandwich complexes [(2,4-dmp)2 Ln(AlMe4 )] (Ln=Y, Lu) and [(2,4-dipp)2 Y(AlMe4 )]. Activation with fluorinated borate/borane co-catalysts gave highly active catalyst systems for the fabrication of polyisoprene, displaying molecular weight distributions as low as Mw /Mn =1.09 and a maximum cis-1,4 selectivity of 90.4 %. The equimolar reaction of half-sandwich complex [(2,4-dtbp)La(AlMe4 )2 ] with B(C6 F5 )3 led to the isolation and full characterization of the single-component catalyst {{(2,4-dtbp)La[(μ-Me)2 AlMe(C6 F5 )]}[Me2 Al(C6 F5 )2 ]}2 . The reaction of the latter complex with 10 equivalents of isoprene could be monitored by 1 H NMR spectroscopy. Also, a donor-induced aluminato/gallato exchange was achieved with [(2,4-dtbp)La(AlMe4 )2 ] and GaMe3 (OEt2 ) leading to [(2,4-dtbp)La(GaMe4 )2 ].

The lanthanide ion praseodymium, Pr(III), was employed to study metallated ion formation and electron transfer dissociation (ETD) of twenty-seven biological and model highly acidic phosphopeptides. All phosphopeptides investigated form metallated ions by electrospray ionization (ESI) that can be studied by ETD to yield abundant sequence information. The ions formed are [M + Pr – H](2+), [M + Pr](3+), and [M + Pr + H](4+). All biological phosphopeptide with a chain length of seven or more residues generate [M + Pr](3+). For biological phosphopeptides, [M + Pr](3+) undergoes more backbone cleavage by ETD than [M + Pr – H](2+) and, in some cases, full sequence coverage occurs. Acidic model phosphorylated hexa- and octa-peptides, composed of alanine residues and one phosphorylated residue, form exclusively [M + Pr – H](2+) by ESI. Limited sequence information is obtained by ETD of [M + Pr – H](2+) with only metallated product ions being generated. For two biological phosphopeptides, [M + Pr + H](4+) is observed and may be due to the presence of at least one residue with a highly basic side chain that facilitates the addition of an extra proton. For the model phosphopeptides, more sequence coverage occurs when the phosphorylated residue is in the middle of the sequence than at either the N- or C-terminus. ETD of the metallated precursor ions formed by ESI generates exclusively metallated and non-metallated c- and z-ions for the biological phosphopeptides, while metallated c-, z-ions and a few y-ions form for the model phosphopeptides. Most of the product ions contain the phosphorylated residue indicating that the metal ion binds predominantly at the deprotonated phosphate group. The results of this study indicate that ETD is a promising tool for sequencing highly acidic phosphorylated peptides by metal adduction with Pr(III) and, by extension, all non-radioactive lanthanide metal ions.

BaGd2 O4 :Eu3+ scintillating phosphors by Pr3+ -codoping were synthesized at 1300°C in air using a solid-state reaction method. The as-synthesized phosphors were characterized by X-ray diffraction (XRD), photoluminescence (PL) including excitation and emission spectra, radioluminescence (RL) spectra excited by X-ray and thermoluminescence (TL) spectra. Both the PL and RL spectra are composed of the featured trivalent europium (Eu3+ ) without any praseodymium (Pr3+ ) ions, and the PL and RL intensities as well as the lifetimes of BaGd2 O4 :Eu3+ scintillating phosphors decrease dramatically with an increasing concentration of Pr3+ ions. Finally, the TL spectra reveal the trap concentration of the existing defects decrease with an increasing concentration of Pr3+ ions, while the relative TL intensity ratio of the high temperature band to the low temperature one increases with an increasing concentration of Pr3+ ions, which results in the afterglow suppression of BaGd2 O4 :Eu3+ scintillating phosphors.

Reactions of N,N'-bis (salicylidene)-1,2-cyclohexanediamine (H2 L) with mixed lanthanide counterions of LnCl3 ·6H2 O and Ln (NO3 )3 ·6H2 O afford six H2 L lanthanide coordination polymers, e.g. {[Pr(H2 L)2 (NO3 )2 Cl]·2CH2 Cl2 }n (1); {[Ln(H2 L)1.5 (NO3 )3 ]2 ·5CHCl3 ·mCH3 OH}n [Ln = Sm (2), Eu (3), Gd (4), Tb (5) and Yb (6); m = 1 (2-5); m = 0 (6)]. X-ray crystallographic analysis reveals that complex 1 exhibits three-dimensional diamondoid topologic structure and complexes 2-6 are of two-dimensional structure. Luminescent spectra show that complexes 1 and 6 have characteristic near-infrared (NIR) emission of praseodymium (III) and ytterbium (III) ions and complexes 2-5 emit luminescence in the visible region. Complexes 3 and 6 reveal sensitive luminescence responses to formaldehyde.

The possibility of using Pr3+ ions to develop multicolor‐emission‐based luminescence thermometry in a single‐band‐ratiometric configuration is investigated for the first time. The thermally induced decrease in intensities of 3P0 → 3F2 and 1D2 → 3H4 emission bands is demonstrated using the excitation matching the ground‐state absorption, and an inverse relation is obtained using the optical excitation matching the excited‐state absorption. The strategy of modulation of the thermometric properties of the Pr3+‐based red‐ and yellow‐emitting single‐band ratiometric (SBR) luminescent thermometers by the activation of the cross‐relaxation (CR) phenomenon promoted by the dopant concentration is elaborated. Contrary to expectations, the {3P0,3H4} ↔ {1D2, 3H6} CR process is shown to cause the high and low dopant concentrations to be optimal for highly sensitive SBR luminescent thermometers operating in the red and yellow spectral ranges, respectively. In both cases, high relative sensitivities of the temperature readout are obtained. These results make Pr3+ ions promising candidates for a SBR thermometry approach.

A flexible one-pot strategy with pyramidal SeIV heteroatoms was employed for the assembly of the praseodymium-containing gly-decorated polyoxotungstate [{Pr3(H2O)10[Se2W22O76(gly)2]}2(Se2W7O30H2)]18− (1 a), which is constructed from one {Se2W7O30H2} unit and two identical {Pr3(H2O)10[Se2W22O76(gly)2]} units. Furthermore, the catalytic performance of Cs2Na4H12[{Pr3(H2O)10[Se2W22O76(gly)2]}2(Se2W7O30H2)]⋅25 H2O (1) for alkene epoxidation with hydrogen peroxide was investigated under mild reaction conditions, and the experimental results suggested that compound 1 exhibits good catalytic performance for the epoxidation of cyclooctene.

The structure and bonding of a Pr-doped boron cluster (PrB7- ) are investigated using photoelectron spectroscopy and quantum chemistry. The adiabatic electron detachment energy of PrB7- is found to be low [1.47(8) eV]. A large energy gap is observed between the first and second detachment features, indicating a highly stable neutral PrB7 . Global minimum searches and comparison between experiment and theory show that PrB7- has a half-sandwich structure with C6v symmetry. Chemical bonding analyses show that PrB7- can be viewed as a PrII [η7 -B73- ] complex with three unpaired electrons, corresponding to a Pr (4f2 6s1 ) open-shell configuration. Upon detachment of the 6s electron, the neutral PrB7 cluster is a highly stable PrIII [η7 -B73- ] complex with Pr in its favorite +3 oxidation state. The B73- ligand is found to be highly stable and doubly aromatic with six delocalized π and six delocalized σ electrons and should exist for a series of lanthanide MIII [η7 -B73- ] complexes.

In this research, computer-aided cooling curve thermal analysis, microstructure analysis, hardness measurements, and tensile test were performed to investigate the effect of praseodymium (Pr) and erbium (Er) additions on as-cast ZRE1 magnesium (Mg) alloys. Results from the cooling curve and microstructure analysis showed that praseodymium and erbium altered the grain size of the alloys. Thermal analysis result demonstrated an increased solidification rate with praseodymium and erbium additions. Furthermore, the grain size was reduced by approximately 16 % and 15 % with the addition of praseodymium and erbium, respectively. Scanning electron microscopy/energy dispersive X-ray spectroscopy results showed that praseodymium combined with the original second phase and formed Mg−Zn-Pr−Ce, and erbium dissolved into the α-Mg matrix. Both additives improved the hardness and ultimate tensile strength of the ZRE1 magnesium alloy.

Using the lanthanide ion praseodymium, Pr(III), metallated ion formation and electron transfer dissociation (ETD) were studied for 25 biological and model acidic peptides. For chain lengths of seven or more residues, even highly acidic peptides that can be difficult to protonate by electrospray ionization will metallate and undergo abundant ETD fragmentation. Peptides composed of predominantly acidic residues form only the deprotonated ion, [M + Pr - H]2+ ; this ion yields near complete ETD sequence coverage for larger peptides. Peptides with a mixture of acidic and neutral residues generate [M + Pr]3+ , which cleaves between every residue for many peptides. Acidic peptides that contain at least one residue with a basic side chain also produce the protonated ion, [M + Pr + H]4+ ; this ion undergoes the most extensive sequence coverage by ETD. Primarily metallated and non-metallated c- and z-ions form for all peptides investigated. Metal adducted product ions are only present when at least half of the peptide sequence can be incorporated into the ion; this suggests that the metal ion simultaneously attaches to more than one acidic site. The only site consistently lacking dissociation is at the N-terminal side of a proline residue. Increasing peptide chain length generates more backbone cleavage for metal-peptide complexes with the same charge state. For acidic peptides with the same length, increasing the precursor ion charge state from 2+ to 3+ also leads to more cleavage. The results of this study indicate that highly acidic peptides can be sequenced by ETD of complexes formed with Pr(III). Copyright © 2017 John Wiley & Sons, Ltd.

Four complexes containing Dy-III and Pr-III ions and their Ln(III)-Zn-II analogs have been synthesized in order to study the influence that a diamagnetic Zn-II ion has on the electronic structure and hence, the magnetic properties of the Dy-III and Pr-III single ions. Single-crystal X-ray diffraction revealed the molecular structures as [Dy-III(HL)(2)(NO3)(3)] (1), [Pr-III(HL)(2)(NO3)(3)] (2), [(ZnDyIII)-Dy-II(L)(2)(CH3CO2)(NO3)(2)] (3) and [(Zn2PrIII)-Pr-II(L)(2)(CH3CO2)(4)(NO3)] (4) (where HL=2-methoxy-6-[(E)-phenyliminomethyl]phenol). The dc and ac magnetic data were collected for all four complexes. Compounds 1 and 3 display frequency dependent out-of-phase susceptibility signals ((M)), which is a characteristic signature for a single-molecule magnet (SMM). Although 1 and 3 are chemically similar, a fivefold increase in the anisotropic barrier (U-eff) is observed experimentally for 3 (83cm(-1)), compared to 1 (16cm(-1)). To rationalize the larger anisotropic barrier (1 vs. 3), detailed ab initio calculations were performed. Although the ground state Kramer's doublet in both 1 and 3 are axial in nature (g(zz)=19.443 for 1 and 18.82 for 3), a significant difference in the energy gap (U-eff) between the ground and first excited Kramer's doublet is calculated. This energy gap is governed by the electrostatic repulsion between the Dy-III ion and the additional charge density found for the phenoxo bridging ligand in 3. This extra charge density was found to be a consequence of the presence of the diamagnetic Zn-II ion present in the complex. To explore the influence of diamagnetic ions on the magnetic properties further, previously reported and structurally related Zn-Dy-III complexes were analyzed. These structurally analogous complexes unambiguously suggest that the electrostatic repulsion is found to be maximal when the Zn-O-Dy-O dihedral angle is small, which is an ideal condition to maximize the anisotropic barrier in Dy-III complexes.

The understanding of surface chemistry changes on oxygen electrodes is critical for the development of reversible solid oxide fuel cell (RSOFC). Here, we report for the first time that the electrochemical potentials can drastically affect the surface composition and hence the electrochemical activity and stability of PrBaCo2 O5+δ (PBCO) electrodes. Anodic polarization degrades the activity of the PBCO electrode, whereas the cathodic bias could recover its performance. Alternating anodic/cathodic polarization for 180 h confirms this behavior. Microstructure and chemical analysis clearly show that anodic bias leads to the accumulation and segregation of insulating nanosized BaO on the electrode surface, whereas cathodic polarization depletes the surface species. Therefore, a mechanism based on the segregation and incorporation of BaO species under electrochemical potentials is considered to be responsible for the observed deactivation and recovery process, respectively.

In this work, the origin of the Raman defects band at 570 cm−1 of praseodymium-doped ceria was revisited from in situ spectra using six different exciting lines between 458 and 785 nm at low temperatures after oxidizing or reducing treatment. The observation of overtones and the fast change of relative intensity with excitation wavelength were explained by a resonance effect around 514 nm, which involved a Pr4+ containing defect stabilized at the oxidized state leading to an absorption band around 530 nm. The reduction of Pr4+ cations contained in such defects modifies the electronic properties of praseodymium doped ceria inhibiting the resonance effect. Additionally, the number of D1 defects that involved Pr3+ cations and oxygen vacancies increased allowing them to be distinguished. Copyright © 2016 John Wiley & Sons, Ltd.

Praseodymium nickelate (Pr2NiO4) is an active oxygen electrode for solid oxide fuel cells, but undergoes phase transition at elevated temperatures (e.g., 750°C). Quantification of this phase evolution in an operating single cell is challenging because of the overlap of X-ray diffraction (XRD) peaks between the cathode and oxide current collector. In this work, we replace the oxide current collector with a gold metal grid, circumventing these challenges by allowing the exposure of the cathode to the X-ray beam, while eliminating peak overlap. Quantification of the phase evolution was performed by a least-squares fitting of the linear combination of XRD standards against the experimental patterns. Energy-dispersive spectroscopy analysis on long-term operated cells showed the absence of reactions between the gold grids and the cathodes. Additionally, the grids exhibited excellent mechanical stability under operating conditions and enabled similar cell performance as an oxide current collector.

The chemistry of lanthanides (Ln=La-Lu) is dominated by the low-valent +3 or +2 oxidation state because of the chemical inertness of the valence 4f electrons. The highest known oxidation state of the whole lanthanide series is +4 for Ce, Pr, Nd, Tb, and Dy. We report the formation of the lanthanide oxide species PrO4 and PrO2 (+) complexes in the gas phase and in a solid noble-gas matrix. Combined infrared spectroscopic and advanced quantum chemistry studies show that these species have the unprecedented Pr(V) oxidation state, thus demonstrating that the pentavalent state is viable for lanthanide elements in a suitable coordination environment.

Two new coordination polymers have been synthesized with 2,5-furandicarboxylic acid upon base modification. The resulting structures are dependent on the base added. When KOH was used as base, potassium was incorporated into the two-dimensional coordination polymer, acting as a metallolinker to give [Pr2K2(OH)2(C6H2O5)3(H2O)3]·H2O (1). Synthesis with other alkali hydroxides produced a three-dimensional metal-organic framework, [Pr8(OH)6(C6H2O5)9(H2O)15]·3H2O (2), and the alkali metal cations were not incorporated into the structure. Hole-size effects with bite-angle analyses indicate that metallolinker formation depends on the cation size. The resulting compounds were characterized by single-crystal X-ray diffraction, powder X-ray diffraction, elemental analysis, and thermogravimetric analysis.

This article reports on the optical characterization of Pr(3) (+) -, Er(3) (+) - and Nd(3) (+) -doped cadmium lead boro tellurite (CLBT) glasses prepared using the melt quenching method. The visible-near infrared (Vis-NIR) absorption spectra of these glasses were analyzed systematically. On measuring the NIR emission spectra of Er(3) (+) :CLBT glasses, a broad emission band centered at 1536 nm ((4) I13 /2 → (4) I15 /2 ) was observed, as were three NIR emission bands at 900 nm ((4) F3 /2 → (4) I9 /2 ), 1069 nm ((4) F3 /2 → (4) I11 /2 ) and 1338 nm ((4) F3 /2 → (4) I13 /2 ) from Nd(3) (+) :CLBT glasses and an NIR emission band at 1334 nm ((1) G4 → (3) H5 ) from Pr(3) (+) :CLBT glasses at an excitation wavelength (λex ) of 514.5 nm (Ar(+) laser). Copyright © 2016 John Wiley & Sons, Ltd.

Pr5 (BO4 )3-x (BO3 )x (F,OH)2.67 O0.28 (x≈1.6), a boron-containing fluoride-oxoapatite-like compound, was obtained by the application of high-pressure/high-temperature synthesis. It exhibits a superstructure of the apatite type with a tripled c lattice parameter (space group P63 /m) and shows complex anion disorder along the 63 screw axis and occupation of distorted octahedra, as well as almost trigonal planar sites, by oxygen and fluorine atoms. Furthermore, a distinct BO4 /(BO3 +F) group disorder is found; 46 % of the sites being occupied by BO4 groups and 54 % by BO3 groups, with a fluoride ion located near the missing oxygen atom. The rare earth cations in the 4f sites exhibit a specific distorted tricapped trigonal prismatic coordination with a mean metaprism twist angle of 21.3°. The crystal structure of Pr5 (BO4 )3-x (BO3 )x (F,OH)2.67 O0.28 (x≈1.6) shows much "flexibility" resulting in split and off-site positions of all other rare earth cations. The title compound therefore combines many structural features of apatite-like compounds, for example biologically highly-important carbonated apatites, shedding more light onto the complex structural chemistry of apatites.

Different kinds of counterions (such as NO3–, ClO4–, and Cl–) play a special role in controlling the framework of coordination compounds. Using this strategy, 5-aminotetrazole-1-propionic acid (Hatzp) was selected to react with praseodymium(III) nitrate or perchlorate in the same solvent system, producing two different coordination compounds, [Pr2(atzp)4(H2O)8]·2NO3·2H2O (1) and [Pr2(atzp)6(H2O)2]·H2O (2). These compounds were structurally characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction. X-ray diffraction analysis revealed that compound 1 displays a dinuclear structure, whereas 2 shows a one dimensional zigzag chain framework. Furthermore, the luminescence properties of compounds 1 and 2 were investigated at room temperature in the solid state.

Herein, hybrid nanocomposite of praseodymium doped TiO2 nanocrystals and graphene oxide nanosheets are prepared by facile hydrothermal treatment. As-synthesized Pr-TiO2 /NGO hybrid nanocomposite exhibits enhanced photocatalytic activity under visible light irradiation by the intact graphene oxide and doped lanthanide mediated band gap narrowing compared to TiO2 . Moreover, high payload and controlled release of doxorubicin by charge reversal of hybrid nanocomposite at endosomal pH and near-infrared irradiation mediated efficient photothermal conversion provide highly favorable features in therapeutic applications. Through the combination of these three distinctive therapeutic modalities, highly efficient trimodal cancer cell ablation is demonstrated.

The gas-phase reaction mechanism was investigated in liquid delivery metalorganic chemical vapor deposition (MOCVD) of praseodymium and lanthanum manganite films. We studied the gas-phase behavior of praseodymium, lanthanum, and manganese precursors under actual CVD conditions by in situ infrared absorption spectroscopy. The rate of the decrease of the infrared absorbance due to Pr(DPM)3 was almost constant even if Mn(DPM)3 was added, indicating that the intermolecular interaction between Pr and Mn precursors in the gas phase is relatively weak in MOCVD of praseodymium manganite films. On the other hand, the temperature dependence of the infrared absorption indicates that the thermal decomposition of La(DPM)3 was promoted in the presence of Mn(DPM)3. The significant intermolecular interaction occurs between La and Mn precursors in the gas phase in MOCVD of lanthanum manganite films. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

As grain boundary (GB) and GB segregation often have significant impact on various properties of polycrystalline materials, their atomic structures as well as the location of segregated dopant should be intensively investigated. We have thus reported several papers about segregation of Pr (praseodymium) in ZnO (zinc oxide) GBs for case study. In this study, we study the atomic structure of Pr-doped ZnO [0001]/(134¯0) Σ13 symmetric tilt GB, and the results are compared with that for the (257¯0) GB [Sato et al., Phys. Rev. B, 87,140101 (2013)]. Although atomic arrangements of these GBs can be characterized using the same kinds of structural units (SUs), Pr segregation sites relative to the SU vary with GBs. It is suggested that change in strain distribution for different GBs would cause the variation in the segregation sites and Pr would prefer the Zn site of locally highest tension.

Recent constraints on supplies of the rare earth elements (REEs) have led to concerns about their long-term availability as well as the consequences that shortages would pose for modern technology. To assess this situation, we apply a comprehensive “criticality” methodology to the REE: lanthanum (La); cerium (Ce); praseodymium (Pr); neodymium (Nd); samarium (Sm); europium (Eu); gadolinium (Gd); terbium (Tb); dysprosium (Dy); holmium (Ho); erbium (Er); thulium (Tm); ytterbium (Yb); lutetium (Lu); and yttrium (Y). Assessments are made on national (U.S. and China) and global levels for the year 2008. Evaluations of each indicator are presented and the results plotted in “criticality space” on a 0 to 100 scale. Over the medium term (5 to 10 years), supply risk (SR) for all REEs is moderate with minimal variation (62.8 to 65.1). Over the long term (10 to 100 years), SR is low (42.1 to 49.2). Environmental implications scores, reflecting the economic allocation of environmental burdens, range from 4.2 for La to 34.4 for Lu. Eu, Er, and Dy have the highest vulnerability to supply restriction (VSR) at the global level (50.6, 49.2, and 47.4, respectively), whereas Sm has the lowest (15.1). This is mainly a reflection of their substitution potential. Similarly, at the national level for the United States and China, Eu and Sm have the highest and lowest VSR scores, respectively, although there are notable differences in scores among the REEs and between countries. Although China's export restrictions render REE supplies inadequate to meet demand at present, our analysis indicates a lower criticality for REEs over the longer term than for a number of other industrially used metals

Single crystals of Pr3S2Cl2[AsS3] were obtained by reacting praseodymium sesquisulfide and trichloride with arsenic and sulfur (molar ratio: 7:4:6:9) in torch-sealed evacuated silica ampoules at 850 °C for a week and subsequent slow cooling to room temperature. The transparent, pale yellowish green platelets crystallize monoclinically (Pr3S2Cl2[AsS3]: a = 2190.96(9) pm, b = 685.49(3) pm, c = 701.87(3) pm, β = 98.752(3)°) in the non-centrosymmetric space group Cc with Z = 4. The crystal structure of Pr3S2Cl2[AsS3] comprises three crystallographically different Pr3+ cations. (Pr1)3+ and (Pr2)3+ exhibit bicapped trigonal prismatic environments of five sulfur and three chlorine atoms (C.N. = 8) each, whereas only seven sulfur atoms arranged as capped trigonal prism (C.N. = 7) are present in the case of (Pr3)3+. Two of the five crystallographically different sulfur atoms (S1 and S2) are coordinated by four Pr3+ cations, each in the shape of slightly distorted [SPr4]10+ tetrahedra (d(S–Pr) = 278–294 pm). Hence, the crystal structure of Pr3S2Cl2[AsS3] contains double chains with the composition 1∞{[S2Pr3]5+}, consisting of two parallel edge-fused chains of anti-SiS2-analogous single strands 1∞{[SPr2]4+}, formed by trans-edge sharing [SPr4]10+ tetrahedra. The arrangement of the 1∞{[S2Pr3]5+} double chains running along [001] can be described as a hexagonal rod-packing. Chloride anions (Cl1 and Cl2) as well as the isolated, ψ1-tetrahedral thioarsenate(III) groups [AsS3]3– (d(As–S) = 228–229 pm) consisting of three sulfur atoms (S3, S4, and S5) and an As3+ cation carrying a stereochemically active non-bonding electron pair take care of the three-dimensional interconnection and the charge balance of the 1∞{[S2Pr3]5+} double chains. All lone pairs at the As3+ cations of the [AsS3]3– pyramids point in the same direction parallel to the c axis of the acentric crystal structure of Pr3S2Cl2[AsS3].

A visible Q-switched pulse train at 639 nm was successfully generated in a Pr-doped double-clad structured waterproof fluoride glass fibre with a semiconductor saturable absorber mirror. The slope efficiency was calculated as 36.3%. The pulse duration and the radio frequency were measured as 270 ns and 107 kHz at 596 mW of absorbed power, respectively. The pulse energy and the pulse peak power were calculated as 1.32 μJ and 4.87 W, respectively.

Seven lanthanide containing strand-like coordination polymers and dimeric complexes were obtained in a reversible reaction from 1, 3-thiazole (thz) and LnCl3 (Ln = La, Ce, Pr, Nd). The reactions do not require activation and render coordination polymers accessible at room temperature, already. The product constitutions depend on the lanthanide and the thiazole-to-halide ratio. For lanthanum and cerium formation of the coordination polymers 1∞[LnCl3(thz)3]·thz as well as dimeric complexes [Ln2Cl6(thz)8]·3thz were observed. For praseodymium and neodymium dimeric complexes were observed with and without non-coordinating thz. Upon heating, the compounds release thiazole under re-formation of LnCl3, the formation reaction thus being a thermally reversible reaction. Compounds and conversion processes were characterized by temperature dependent X-ray powder and single-crystal X-ray diffraction, in-situ temperature dependent gas phase IR spectroscopy, DTA/TG, and elemental analysis.

The first derivatives of praseodymium-containing metallofullerenes are formed through regioselective cycloaddition of adamantylidene carbene to Pr@C2v(9)-C82, and two isomers out of the 35 possible monoadducts are successfully isolated. Optical adsorption and electrical chemistry characterizations indicate that the electronic property of Pr@C2v(9)-C82 is largely pertained in these derivatives, since their π-electron systems are not altered markedly.

The 2D-coordination polymer 2∞[Ce2Cl6(bipy)4]·py (bipy = 4, 4′-bipyridine) shows a 5d-4f centered emission in the soft UV-B region. It was synthesized via the reaction of anhydrous CeCl3 and 4, 4′-bipyridine in pyridine under solvothermal conditions. The two-dimensional sheet structure consisting of 4, 4′-bipyridine coordinated Ce2Cl6 dimers closes the gap between the known lanthanum 3∞[La2Cl6(bipy)5]·4bipy framework and the 2D networks of the formula 2∞[Ln2Cl6(bipy)3]·2bipy from praseodymium on. They differ in the number of coordinating bipy linkers, which decreases along La > Ce > Pr, with the remarkable observation that lanthanum, cerium, and praseodymium exhibit different network constitutions. The structure of 2∞[Ce2Cl6(bipy)4]·py exhibits a cem topology constituted of double strands, which are diagonally linked by 4, 4′-bipyridine forming trapezoid cavities in-between the strands. The cavities contain intercalated pyridine molecules.

The light green transparent glaze was prepared by introducing praseodymium oxide as a colorant used in raw glaze. The effect of Pr6O11 on the thermal and color properties of the transparent glaze was investigated by thermogravimetry and differential thermal analysis and reflection spectra, respectively. The introduction of Pr6O11 could not form new crystalline phases in the transparent glaze. The glass transition temperature and melting temperature of the transparent glaze decreased with the increasing Pr6O11, which is due to the high field strength of Pr ion. In addition, the mechanism of color formation in the glaze containing Pr6O11 was also discussed.

A 3D organic-inorganic hybrid compound, (2-MepyH)3 ({Fe(1,10-phen)3}3)({Pr4Sb12O18(OH) Cl11.5}(TDC)4.5({Pr4Sb12O18(OH)Cl9.5} Cl))·3 (2-Mepy)·28 H2 O( 1; 2-Mepy = 2- methylpyridine, 1,10-phen = 1,10-phe- nanthroline, H2TDC = thiophene-2,5- dicarboxylic acid), was hydrothermally synthesized and structurally character- ized. Unusually, two kinds of high-nu- clearity clusters, namely ((Pr4Sb12O18 (OH)Cl11)(COO)5) 5� and ((Pr4Sb12O18 (OH)Cl9)Cl(COO)5) 4� , coexist in the structure of compound 1; two of the latter clusters are doubly bridged by two m2-Clmoieties to form a new centrosymmetric dimeric cluster. An unprecedented spontaneous and reversA single-crystal-to-single-crys- tal transformation was observed, which simultaneously involved a notable or- ganic-ligand movement between the metal ions and an alteration of the bridging ion in the dimeric cluster, in- duced by guest-release/re-adsorption, thereby giving rise to the intercon- version between compound 1 and the compound (2-MepyH)3({Fe(1,10- phen)3}3)({Pr4Sb12O18(OH)Cl11.5}(TDC)4- ({Pr4Sb12O18Cl10.5(TDC)0.5(H2O)1.5}O0.5))· 25 H2 O( 1'). The mechanism of this transformation has also been discussed in great detail. Photocatalytic H2-evolu- tion activity was observed for com- pound 1' under UV light with Pt as a co-catalyst and MeOH as a sacrificial electron donor.

A tetramer cluster complex of the formula [Pr4Cl10(OH)2(thz)8(H2O)2] was prepared constituted by two edge sharing metal triangles coordinated by thiazole (thz) and chloride ligands bent together by opposing μ3-hydroxide and chloride capping for both triangles. The tetramer is the first thiazole complex of a lanthanide ion and shows a previously unknown symmetric capping mode. It co-crystallizes with an anhydrous dimeric complex of the formula [Pr2Cl6(thz)8] in equal amounts.

The intermetallic zinc compounds AAu4Zn2 (A = Ca, Ce, Pr, Nd) were obtained by induction melting of the elements in sealed tantalum tubes. The samples were studied by X-ray diffraction on powders. The structures of the calcium and the cerium compound were refined from single crystal diffraction data: YbAl4Mo2 type, I4/mmm, a = 692.8(1), c = 527.6(1) pm, wR2 = 0.0304, 244 F2 values and 11 variables for CaAu4.08Zn1.92 and a = 699.6(1), c = 531.2(1) pm, wR2 = 0.1152, 186 F2 values and 10 variables for CeAu4Zn2. The 4d site of the calcium compound shows small mixed Zn/Au occupancy. The AAu4Zn2 structures consist of three-dimensional gold networks (272–286 pm Au–Au in CeAu4Zn2), which are penetrated by linear infinite zinc chains (266 pm Zn–Zn in CeAu4Zn2) that extend along the c axis. The calcium or rare earth atoms fill Au12 cavities within the networks. Temperature dependent magnetic susceptibility measurements reveal Pauli paramagnetism for CaAu4Zn2 and Curie-Weiss paramagnetism for the cerium, praseodymium, and neodymium compound, respectively. No magnetic ordering was evident down to 2.5 K. The static intermediate-valent compound Ce2RuZn4 crystallizes with a superstructure of CeAu4Zn2 (klassengleiche subgroup P4/nmm) with a different but fully ordered substitution on the transition metal sites. This structural relationship is discussed on the basis of a group-subgroup scheme.

Three discrete early-lanthanide complexes with cyclic polyoxovanadate ligands, [LaV10O30]7– (1), [CeV9O27]6– (2), and [PrV9O27]6– (3), were synthesized by reaction of [VO3]– with early-lanthanide(III) salts. Complexes 1–3 were composed of a LnIII center in square-antiprism coordination mode with coordinated all-inorganic ligands [VnO3n]n– (n = 9 or 10), which were constructed from a cyclic linkage of nine or ten VO4 tetrahedra through vertex sharing. Structural investigation of lanthanum complex 1 revealed a ten-membered ring of VO4 units in which eight VO4 units were coordinated to the lanthanum atom through their oxido groups and two VO4 units at opposite sides of the ring were not coordinated. Cerium complex 2 and praseodymium complex 3 both contained a nine-membered cyclic ligand with eight VO4 coordinated units and one uncoordinated unit among nine tetrahedral VO4 units. 51V NMR spectra of 1–3 in acetonitrile showed reversible temperature dependences at –40–70 °C, thus indicating fluxional behavior of the macrocyclic polyoxovanadate ligands in solution. Exchange of the coordinated and uncoordinated VO4 sites in the ring was responsible for these reversible processes.

The first utility of praseodymium as a mediating metal in the Barbier reaction of carbonyl compounds with allyl halides was reported in this paper. In contrast to the traditional metal-mediated or catalyzed Barbier reactions, exclusive α-adducts were obtained in this one-pot reaction with a broad scope of substrates and feasible reaction conditions.

The chemistry of lanthanides (Ln=La-Lu) is dominated by the low-valent +3 or +2 oxidation state because of the chemical inertness of the valence 4f electrons. The highest known oxidation state of the whole lanthanide series is +4 for Ce, Pr, Nd, Tb, and Dy. We report the formation of the lanthanide oxide species PrO4 and PrO2 (+) complexes in the gas phase and in a solid noble-gas matrix. Combined infrared spectroscopic and advanced quantum chemistry studies show that these species have the unprecedented Pr(V) oxidation state, thus demonstrating that the pentavalent state is viable for lanthanide elements in a suitable coordination environment.

The chemistry of the lanthanides is mostly dominated by compounds in the oxidation state +III. Only few compounds of Ce, Pr, and Tb are known with the metal in the +IV oxidation state. Removal of the last f-electron on praseodymium +IV would lead to a closed-shell system with formal oxidation state V. In this work we investigated the stability of the PrF5 molecule by theory and matrix-isolation techniques through the reaction of laser-ablated praseodymium atoms with fluorine in excess of neon, argon, krypton, or neat fluorine. Besides the known PrF3 molecule, unreported IR bands for PrF4 could be observed, and there is evidence for the formation of PrF and PrF2 but not for the formation of PrF5.

By syntheses and characterization of the imidazolate frameworks 3∞[Sm3(Im)9(ImH)2]·2ImH, Im– = imidazolate anion, ImH = 1H-imidazole 3∞[Gd2(Im)6(ImH)1.5]·0.5ImH and 3∞[Dy(Im)3] it is shown that the constitution of 3D-linked lanthanide imidazolates is variable and refers to the lanthanide contraction and the course of the ionic radii of Ln3+ and thus the coordinative demand of the referring ions. The larger the trivalent ion the more neutral imidazole molecules are incorporated, both coordinating and non-coordinating starting with no imidazole and homoleptic frameworks for Ln = Tb, Dy and ranging to a ratio Ln:ImH of 1:2 for praseodymium in 3∞[Pr(Im)3(ImH)]·ImH. Samarium and gadolinium mark steps in this course with ratios of 3:4 and 1:1. Although the constitution differs, the lanthanide ions show only a slight change in C.N. ranging from six to seven. Major differences are observed in the framework structures and topologies as well as density concerning available free space after imidazole release. Kagome nets are a prominent topological feature of imidazole containing constitutions, whereas cubic 4, 6 nets are found for homoleptic imidazolates.

The reactions of the aromatic ketones benzophenone and 9-fluorenone with trivalent [LnL3] complexes [Ln = Ce, Pr; L = N(SiMe3)2, C5H5 (Cp)] produce highly colored solutions in toluene. Characterization of these complexes by X-ray diffraction revealed them to be monoadducts of the form [LnL3(ketone)]. The crystallographically determined C–O bonds of these complexes are longer than those of the free ketones. Significant ligand-to-metal charge transfer is also indicated by the ν(C=O) vibration of the coordinated ketone, which appears at lower wavelength. Solution-based 1H NMR spectroscopy showed paramagnetic spectra of complexes Ln[N(SiMe3)2]3(ketone) and Ln(C5H5)3(ketone), which further supports this finding.

While the properties of functional oxide thin films often depend strongly on their oxygen stoichiometry, there have been few ways to extract this information reliably and in situ. In this work, the derivation of the oxygen non-stoichiometry of dense Pr0.1Ce0.9O2−δ thin films from an analysis of chemical capacitance obtained by impedance spectroscopy is described. Measurements are performed on electrochemical cells of the form Pr0.1Ce0.9O2−δ/Y0.16Zr0.84O1.92/Pr0.1Ce0.9O2−δ over the temperature range of 450 to 800 °C and oxygen partial pressure range of 10−5 to 1 atm O2. With the aid of a defect equilibria model, approximations relate chemical capacitance directly to non-stoichiometry, without need for fitting parameters. The calculated non-stoichiometry allows extraction of the thermodynamic constants defining defect generation. General agreement of these constants with bulk values derived by thermogravimetric analysis is found, thereby confirming the suitability of this technique for measuring oxygen non-stoichiometry of thin oxide films. Potential sources of error observed in earlier chemical capacitance studies on perovskite structured oxide films are also discussed.