Iron(III) and Cobalt(III) Complexes with Oxalate and Phenanthroline: Synthesis,Crystal Structure,Spectroscopy Properties and Magnetic Properties

We report herein the synthesis and physicochemical characterization of two mixed-ligand complexes of the following stoichiometric formulae: [Fe(phen)₂(ox)](NO₃)?2H₂O (1) and [Co(phen)₂(ox)](NO₃)?4H₂O (2) (as phen: 1,10-orthophenanthroline; ox: oxalate dianion). Both compounds have been prepared by slow evaporation at room temperature and characterized by single-crystal X-ray diffraction. They have been characterized by IR and UV–Vis spectra and thermoanalysis (TG and DTA) The structures of these compounds are highly symmetric. Indeed, the two compounds are isomorphous and crystallize in the orthorhombic space group Ibca. In each material, the M^III ion has a slightly distorted square bipyramidal environment, coordinated by one oxalate ion and two 1,10-orthophenanthroline ligands. Structural cohesion is established essentially by π–π interactions between the rings of phen groups and intermolecular O–H…O hydrogen bonds connecting the ionic entities and uncoordinated water molecules. Magnetic susceptibility measurements of (1) in the range 5–300 K exhibit paramagnetic behavior at high temperature. However, at low temperature, the magnetic data show the occurrence of weak antiferromagnetic intermolecular interactions between the local spins.     

Pt–Ru decorated self-assembled TiO2–carbon hybrid nanostructure for enhanced methanol electrooxidation

Porous titanium oxide–carbon hybrid nanostructure (TiO₂–C) with a specific surface area of 350 m²/g and an average pore-radius of 21?·?8 Å is synthesized via supramolecular self-assembly with an in situ crystallization process. Subsequently, TiO₂–C supported Pt–Ru electro-catalyst (Pt–Ru/TiO₂–C) is obtained and investigated as an anode catalyst for direct methanol fuel cells (DMFCs). X-ray diffraction, Raman spectroscopy and transmission electron microscopy (TEM) have been employed to evaluate the crystalline nature and the structural properties of TiO₂–C. TEM images reveal uniform distribution of Pt–Ru nanoparticles (d _Pt???Ru ?=?1·5–3·5 nm) on TiO₂–C. Methanol oxidation and accelerated durability studies on Pt–Ru/TiO₂–C exhibit enhanced catalytic activity and durability compared to carbon-supported Pt–Ru. DMFC employing Pt–Ru/TiO₂–C as an anode catalyst delivers a peak-power density of 91 mW/cm² at 65 °C as compared to the peak-power density of 60 mW/cm² obtained for the DMFC with carbon-supported Pt–Ru anode catalyst operating under similar conditions.     

Synthesis and luminescent study of diphosphine-Pt-diacetylide complexes for OLED

Two novel diphosphine-Pt-diacetylide complexes were synthesized and characterized by ¹H NMR, mass spectrometry and elemental analysis. As a diphosphine, 1,8-bis-(diphenylphosphino)naphthalene (dppn) was prepared and chelated to the Pt(II) center, and p-tolylacetylide (4-CCC₆H₄CH₃) or p-fluorophenylacetylide (4-CCC₆H₄F) was then incorporated to Pt(II) as an anion. The photophysical properties of the Pt complexes were investigated with UV–Vis spectroscopy, photoluminescence (PL) spectroscopy and transient PL. MLCT absorptions of (dppn)Pt(4-CCC₆H₄CH₃)₂ (1) and (dppn)Pt(4-CCC₆H₄F)₂ (2) were observed at 325 and 320 nm, respectively. To investigate emission properties of the films doped with 1 and 2, these Pt complexes were spin-coated with CBP or MCP. The solid films doped with 1 and 2 showed luminescence at 530 and 520 nm, respectively. Energy transfer from MCP to 1 and 2 seemed to be efficient because luminescence of MCP was not observed. The excited state lifetimes of these complexes were 13–17 ns at room temperature and 17 and 84 ns at 20 K, indicating that the prominent luminescence was fluorescence and the intersystem crossing through LS coupling is rather weak.     

Enhanced optoelectronics properties of europium(III) complexes with β-diketone and nitrogen heterocyclic ligands

Preparation and photoluminescence behavior of six new europium complexes with β-diketone 1-(2-hydroxy phenyl)-3-phenylpropane-1,3-dione (HPPP) and bathophenanthroline (batho), 2,2′-bipyridyl (bipy), 2,2′-biquinoline (biq), neocuproin (neo) and 1,10-phenanthroline (phen) are reported in solid state. The ligand (HPPP) and complexes Eu(HPPP)₃·H₂O (1), Eu(HPPP)₃·phen (2), Eu(HPPP)₃·batho (3), Eu(HPPP)₃·bipy (4), Eu(HPPP)₃·biq (5) and Eu(HPPP)₃·neo (6) were characterized by means of elemental analysis, infrared spectroscopy, proton nuclear magnetic resonance (¹H-NMR). The optical properties, thermal stability and crystalline nature were investigated by photoluminescence spectroscopy, thermogravimetric analysis and XRD respectively. The emission spectra show narrow intense emission band of central europium (III) metal ion that arise from the high intense ⁵D₀ → ⁷F₀ transition. The introduction of ancillary ligands like batho, bipy, biq, neo, phen enlarged the π-conjugation system in complexes as a result higher luminescence intensity, longer life time (τ) and higher quantum efficiency (η) observed in europium ternary complexes in comparison to Eu(HPPP)₃·H₂O (1). Based on the emission spectra, the luminescence decay curve was measured which indicated that the transfer of energy from HPPP ligand to the europium metal is more efficient in complexes 2–6 than complex 1.     

In situ synthesis and luminescence characteristics of complexes of europium(III) with 4,6-diacetylresorcinol

The complexes of europium(III) with 4,6-diacetylresorcinol (H₂DAR) and a co-ligand (phen, bpy or 2,2′-bipyridine N,N′-dioxide (2,2′-bpyO₂)) were in situ synthesized in silica matrix via a two-step gel process. The formation of complexes in silica gel was confirmed by the luminescence excitation spectra. The silica gels that contain in situ synthesized europium complexes exhibit the characteristic emission bands of the Eu(III). The results show that there are two ways to enhance the emission intensity of the Eu(III): (i) synthesize the complex in silica matrix and (ii) synthesize the complex with a co-ligand, which coordinates with Eu(III) in the composite system and can efficiently transfer the energy from 4,6-diacetylresorcinol to the Eu(III). The order of the luminescence intensities of the complexes is: Eu₂(DAR)₃(phen)₂-(sol–gel) > Eu₂(DAR)₃(2,2′-bpyO₂)₂-(sol–gel) > Eu₂(DAR)₃ (bpy)₂-(sol–gel) > Eu₂(DAR)₃-(sol–gel) > pure Eu₂(DAR)₃·4H₂O.     

Studies on the effect of organic additives on the monolithicity and optical properties of the rhodamine 6G doped silica xerogels

Rhodamine 6G (R6G) laser dye doped silica xerogels were prepared by sol–gel processing using tetraethylorthosilicate [TEOS, Si(OC₂H₅)₄] precursor, citric acid (CTA) catalyst and ethanolic R6G in the presence of various organic additives such as formamide (FA), N′methylformamide (N′MF), dimethylformamide (DMF), acetamide (AA), glycerol (GLY), oxalicacid (OXA), ethyleneglycol (EG) and diethyleneglycol (DEG). The organic additive/TEOS molar ratio was varied from 0.001 to 0.1 by keeping the TEOS/EtOH/H₂O/CTA/R6G molar ratio constant at 1:5:7:1.2×10⁻³:9.2×10⁻⁶. It was found from the spectral studies of the additive modified R6G doped silica xerogels that the absorption maxima at 530 nm and emission maxima at 565 nm were increased with the addition of organic additive and with the increase of the additive/TEOS molar ratio. The transparency of the R6G doped silica xerogels was increased with the increase of additive/TEOS molar ratio from 0.001 to 0.1 with OXA, DEG and EG and in the case of DMF, N′MF, FA, AA and GLY, the transparency of the samples increased up to 0.014 of additive/TEOS molar ratio and then decreased for >0.014 of additive/TEOS molar ratio. Monolithic samples were obtained with all the organic additives. The percentage volume shrinkage of the samples was less EG and DEG and more with OXA additives.     

X-ray study of weak interactions in two flavonoids

X-ray diffraction studies were carried out on single crystals of two flavonoids, viz. 5-hydroxy-6,7,4′-trimethoxyflavone, C₁₈H₁₆O₆, (I) and 5-hydroxy-3,7,4′-trimethoxyflavone, C₁₈H₁₆O₆, (II). Crystal structures of both the flavonoids were solved by direct methods and refined by full-matrix least-squares procedures. In both the molecules, the benzopyran moiety is planar. The dihedral angle between the phenyl ring and the benzopyran portion is 5.50(4)° in (I) and 29.11(5)° in (II). In (I), the crystal packing is influenced by O-H…O hydrogen bonds, and weak C-H…O and π…π interactions whereas in (II) the crystal structure is stabilized by the presence of four intermolecular short contacts of the type C-H…O. There is also one C-H…π hydrogen bond with H… centroid distance of <2.7 Å. The molecules are further stabilized by π-π interactions.     

Synthesis,structural characterization and photophysical properties of highly photoluminescent crystals of Eu(III), Tb(III) and Dy(III) with 2,5-thiophenedicarboxylate

Lanthanide compounds of general formula [Ln₂(2,5-tdc)₃(dmf)₂(H₂O)₂]·2dmf·H₂O (Ln = Eu(III) (1), Tb(III) (2), Gd(III) (3) and Dy(III) (4), dmf = N,N′-dimethylformamide and 2,5-tdc²⁻ = 2,5-thiophedicarboxylate anion) were synthesized and characterized by elemental analysis, X-ray powder diffraction patterns, thermogravimetric analysis and infrared spectroscopy. Phosphorescence data of Gd(III) complex showed that the triplet states (T₁) of 2,5-tdc²⁻ ligand have higher energy than the main emitting states of Eu(III), Tb(III) and Dy(III), indicating that 2,5-tdc²⁻ ligand can act as intramolecular energy donor for these metal ions. An energy level diagram was used to establish the most relevant channels involved in the ligand-to-metal energy transfer. The high value of experimental intensity parameter Ω₂ for the Eu(III) complex indicate that the europium ion is in a highly polarizable chemical environment. The emission quantum efficiency (η) of the ⁵D₀ emitting level of Eu(III) was also determined. The complexes act as possible light conversion molecular devices (LCMDs).     

Fabrication of Pt, Pt–Cu, and Pt–Sn nanofibers for direct ethanol protonic ceramic fuel cell application

Poly(vinyl pyrrolidone) with a M _w of 1.3 × 10⁶ g/mol (PVP) or 4 × 10⁴ g/mol (PVP_Low) was used as a polymer to fabricate PVP–Pt, PVP–Pt–Cu, and PVP_Low–Pt–Sn composite fibers by electrospinning. The effect of varying the electrospinning conditions on the fiber morphology was investigated, and the solution composition and electrospinning parameters were optimized to obtain composite fibers with a minimal bead formation. Pt, Pt–Cu, and Pt–Sn metal nanofibers were then obtained by heat treatment of the respective PVP–metal or PVP_Low–metal composite fibers at 300, 350, and 450 °C, respectively, in air for 5 h. Single cells of a direct ethanol protonic ceramic fuel cell were subsequently fabricated by applying the metal nanofibers, or a commercial Pt paste, as the anode on the surfaces of BaY_0.2Zr_0.8O_3?δ pellets and Pt paste as the cathode. The I–V polarization results showed that the metal nanofiber-based anode single cells provided higher maximum power densities than that of the Pt paste anode, with the Pt nanofiber-based anode single cell producing the highest maximum power density of 0.58 mW/cm² at 550 °C.     

Structural properties and visible emission of Eu3+-activated SiO2–ZnO–TiO2 powders prepared by a soft chemical process

In this work, the structural and optical properties of the 60SiO₂–20ZnO–20TiO₂ system (in mol%) doped with 1 mol% of Eu³⁺ were evaluated. Stable and transparent sols, homogeneous gels, and powders were prepared by a soft chemical process followed by annealing from 700 to 1100 °C. Visible emission was observed in the photoluminescence (PL) spectra from 570 to 700 nm owing to the Eu³⁺ ions, with the most intense emission peaks at 614 and 590 nm related to the ⁵D₀ → ⁷F₂ and ⁵D₀ → ⁷F₁ transitions, corresponding to red (R) and orange (O) colors, respectively. The R/O intensity ratios between 3.16 and 3.73 were observed and correlated to the structural properties of the host. X-ray diffraction patterns indicated that the reduction of PL at 614 nm and changes in the R/O values were due to the crystallization process. In addition, the FTIR spectra showed a gradual decrease of the hydroxyl absorption bands around 3436 and 1640 cm⁻¹ and an increase of the bands related to Ti–O–Ti and Si–O–Si linkages, indicating polymerization and densification process of the host was achieved above 700 °C. Moreover, increasing the annealing temperature resulted in the formation of ZnTiO₃ and Zn₂TiO₄ crystalline phases, as well as rutile TiO₂. Finally, intensity parameters (Ω_λ), and quantum efficiency were calculated by applying Judd–Ofelt theory to Eu³⁺ ions, which showed that the Eu³⁺-doped samples can be used in displays and LEDs.     

Electrical properties of complex bimetallic salts [M(N–N)3]2+[Cu(MNT)2]2− and heterobimetallic AgI–CuII/HgII–CuII bis(maleonitriledithiolato) bridged coordination polymers

This paper presents the solid-state electrical conductance properties of a series of complex bimetallic salts of the form [M(N–N)₃][Cu(MNT)₂] (M=Fe(II), Co(II), Ni(II), or Cd(II); N–N=1,10-phenanthroline (phen) or ethylenediamine (en); MNT²⁻=maleonitriledithiolate) and bridged heterobimetallic complexes Ag₂[Cu(MNT)₂] and Hg[Cu(MNT)₂] that have been prepared by treatment of complex salt Na₂[Cu(MNT)₂] (generated in situ) with one equivalent of cationic complexes [M(N–N)₃]X₂ or Hg(CH₃COO)₂ and two-equivalent of AgNO₃ in aqueous–methanol mixture and characterised by relevant spectroscopies (IR, EPR, UV-Visible) as well as by powder XRD spectra. Solution conductivity measurements in 10⁻³ M DMSO solution revealed 1:1 electrolytic behaviour of the bimetallic salts. Diamagnetism together with powder EPR spectra for Ag₂[Cu(MNT)₂] and Hg[Cu(MNT)₂] show strong antiferromagnetic interaction between two adjacent copper(II) centers at room temperature. Majority of the complexes exhibited compressed pellet σ_rt in 8.19×10⁻¹¹ to 5.37×10⁻⁷ S cm⁻¹ range and show semiconductivity over the 303–383 K temperature range. Conductivity of both coordination polymers are appreciably higher compared to the bimetallic salts. For the salts [Co(phen)₃][Cu(MNT)₂], [Ni(phen)₃][Cu(MNT)₂] and bridged complexes Ag₂[Cu(MNT)₂] and Hg[Cu(MNT)₂] the conductivity remarkably increases, i.e., 10² to 10³ order of magnitude at elevated temperature showing some sort of phase transformation producing S⋯S intermolecular contact.     

Constructing Built‐in Electric Field in Ultrathin Graphitic Carbon Nitride Nanosheets by N and O Codoping for Enhanced Photocatalytic Hydrogen Evolution Activity

Codoping of N and O in ultrathin graphitic carbon nitride (g‐C₃N₄) nanosheets leads to an inner electric field. This field restrains the recombination of photogenerated carriers and, thus, enhances hydrogen evolution. The layered structure of codoped g‐C₃N₄ nanosheets (N‐O‐CNNS) not only provides abundant sites of contact with the reaction medium, but also decreases the distance over which the photogenerated electron–hole pairs are transported to the reaction interface. Quantum confinement in the ultrathin structure results in an increased bandgap and makes the photocatalytic reaction more favorable than bulk g‐C₃N₄. Under visible light irradiation, N‐O‐CNNS with 3 wt% Pt achieves a hydrogen evolution rate of 9.2 mmol g^?1 h^?1 and a value of 46.9 mmol g^?1 h^?1 under AM1.5 with 5 wt% Pt. Thus, this work paves the way for designing efficient nanostructures with increased separation/transfer efficiency of photogenerated carriers and, hence, increased photocatalytic activities.     

Silver-triphenylphosphine coordination polymers with linear spacer ligands

In the presence of PPh₃, AgX (X = ClO₄⁻, I⁻, NO₃⁻, CH₃CO₂⁻) and linear spacer ligands 4,4′-bipyridine (bpy), 1,4-diazobicyclo[2,2,2]octane (dabco) and pyrazine (pyz) react to form [{Ph₃PAg}₂(μ-bpy)](ClO₄)₂ (1), [{Ph₃PAgI}₂(μ-bpy)]_n (2), [{(Ph₃P)Ag(ONO₂)}₂(μ-bpy)]_n (3), [{Ag(μ-OAc)}₂(μ-bpy)₂]_n.6nH₂O (4), [{(Ph₃P)Ag(NO₃)}₂(μ-dabco)]_n (5) and [Ag(NO₃)(μ-pyz)]_n (6). The structures of 1–4 were determined by X-ray crystallography. Compound 1 contains a binuclear cation and two ClO₄⁻ anions with very weak interactions between silver and ClO₄⁻ anions, whereas 2 and 3 are stair-step undulating polymer chains. A ladder type of structure was observed in 4 in which two of the [Ag(μ-bpy)]_n linear chains are bridged by two acetate ligands and paired by Ag..Ag interactions of 3.1347(8) Å and π–π interactions of 3.67-3.63 Å.     

Spectroscopic properties of Sm3+-doped oxy-fluoride powders with various Sm3+ concentration and sintering temperature

Sm³⁺-doped oxy-fluoride (OFSm) powders are prepared by the melt quenching technique and characterized using FE-SEM, optical absorption and emission techniques. Spectroscopic properties of Sm³⁺-doped oxy-fluoride powders with different Sm³⁺ concentration and sintering temperature are presented and discussed by using the absorption, emission measurements. The Judd–Ofelt intensity (J–O) parameters (Ω_λ, where λ = 2, 4 and 6), measured from the experimental oscillator strengths of the absorption spectra, are used to evaluate the radiative parameters of the fluorescence transitions. Intense orange emission can be obtained when excited with 325 nm wavelength by increasing the sintering temperature to 1400 °C. Ratio of fluorescence intensities arising from the two closing lying ⁴F_3/2 and ⁴G_5/2 levels is studied, concentration quenching has been noticed beyond 2 mol% of Sm³⁺ ions concentration. The excellent spectroscopic properties along with the outstanding thermal stability suggest that the OFSm03 powders may become an attractive laser material to exhibit efficient visible lasing emission in the orange spectral region.     

Structure and photoluminescence property of complexes of aromatic carboxylic acid-functionalized polysulfone with Eu(Ⅲ) and Tb(Ⅲ)

With chloromethylated polysulfone as starting substance, naphthoic acid (NA) and benzoic acid (BA) were bonded onto the side chains of polysulfone (PSF) via polymer reactions, obtaining two kinds of aromatic carboxyl acid-functionalized polysulfone, PSFNA and PSFBA. Subsequently, the luminescent binary and ternary polymer-rare earth complexes of Eu(Ⅲ) and Tb(Ⅲ) were prepared through coordination reactions, respectively, with PSFNA and PSFBA as macromolecule ligands and with 1,10-phenanthroline (Phen) and 4,4′-bipyridine (Bipy) as small-molecule co-ligands. This work focuses on investigating the relationship between structure and photoluminescence property of these complexes. The experimental results indicate that the macromolecule ligands PSFNA and PSFBA can strongly sensitize the fluorescence emissions of Eu³⁺ ion or Tb³⁺ ion, and the sensitization effect is strongly dependent on the structure of the ligands and the property of the central ions. The fluorescence emission of the binary complex PSF–(NA)₃–Eu(Ⅲ) is stronger than that PSF–(BA)₃–Eu(Ⅲ), suggesting the bonded ligand NA has stronger sensitization action for Eu³⁺ ion than ligand BA; The binary complex PSF–(BA)₃–Tb(Ⅲ) emit very strong characteristic fluorescence of Tb³⁺ ion, displaying that ligand BA can strongly sensitize Tb³⁺ ion, whereas PSF–(NA)₃–Tb(Ⅲ) does not emit the characteristic fluorescence of Tb³⁺ ion, showing that the bonded ligand NA does not sensitize Tb³⁺ ion. The fluorescence intensity of the ternary complexes is stronger than that of the binary complexes in the same series. The solid films of these complexes also emit the strong characteristic fluorescence of Eu³⁺ ion or Tb³⁺ ion.     

New complexes of europium and gadolinium with 2,4,6-trichlorophenyl acetoacetate as ligand

The synthesis, characterization and photoluminescent properties of new europium complexes with 2,4,6-trichlorophenyl acetoacetate (TCA) and 3-amino-2-carboxypyridine-N-oxide (picNO) ligands have been investigated. Results of the characterization are in agreement with the molecular formula proposed. The emission spectra at 77 K of the [Eu(TCA)₂(H₂O)₅]OH and [Eu(TCA)₂(picNO)(H₂O)₂]OH complexes, excited at 333 nm, display the typical transitions of the europium ion, ⁵D₀ → ⁷F_J (J = 0-4), indicating an efficient luminescence sensitization of this ion by the TCA ligand. The satisfactory agreement between experimental and theoretical absorption spectra of the organic part of the complexes suggests that the geometries optimized by the Sparkle model are correct. These results suggest these complexes as potential candidates as useful markers.     

Molybdenum ion: a structural probe in lithium–antimony–germanate glass system by means of dielectric and spectroscopic studies

In this study, we have synthesized multi-component 10Li₂O–(30 ? x)Sb₂O₃–40GeO₂–20PbO:x MoO₃ (with five values of x ranging from 1.0 to 9.0) and investigated dielectric properties over a frequency range of 10²–10⁶ Hz and in the temperature range 30–300 °C of these samples. The evaluated dielectric parameters include dielectric constant, ε′(ω); ac conductivity, σ _ac; and electric modulus, M(ω). The results were interpreted with the aid of the experimental data on optical absorption, IR, Raman, and ESR spectroscopy. The analysis of the results of spectroscopic studies have indicated that a considerable proportion of molybdenum ions reduce to Mo⁵⁺ state, form molybdenyl complexes, occupy octahedral positions, act as modifiers, and create dangling bonds in the glass network. The concentration of such molybdenyl complexes seemed to be increasing with increase in the concentration of MoO₃. The temperature dispersion of real part of dielectric constant, ε′(ω), has been analyzed using space charge polarization model. The frequency and temperature dependence of the dielectric loss parameters have exhibited relaxation character. The relaxation effects have been attributed to molybdenyl complexes and to the divalent lead ions. Electrical conductivity exhibited an increasing trend and the activation energy showed a decreasing trend with increase in the concentration of MoO₃. The increase of conductivity is attributed to (i) the increasing concentration of polaron Mo⁵⁺–Mo⁶⁺ pairs and (ii) increase in the concentration of dangling bonds in the glass network that causes the substantial decrement in jump distance for Li⁺ ions, which contribute to ionic conductivity.     

Effects of niobium content on electrical and mechanical properties of (Na0.85K0.15)0.5Bi0.5Ti(1-x)Nb x O3 thin films

(Na_0.85K_0.15)_0.5Bi_0.5Ti_(1-x)Nb _x O₃ (NKBT-N100x) thin films were deposited on Pt/Ti/SiO₂/Si(100) substrates by metal–organic decomposition method and annealed in oxygen atmosphere at 750 °C. The effects of niobium concentration on the microstructures, ferroelectric, piezoelectric, leakage current and mechanical properties of the NKBT-N100x (x = 0, 0.01, 0.03, 0.05) thin films have been investigated in detail. The NKBT-3N thin film has the largest remnant polarization (7 μC/cm²) and statistically averaged d _33eff (140 pm/V), the smallest leakage current, elasticity modulus (102.0 Gpa), hardness (5.1 Gpa) and residual stress (297.0 Mpa). The evaluation of residual stresses of these thin films will offer useful guidelines of safe working condition for their potential application in microelectromechanical system.     

Effects of deposition temperature on phase purity, orientation, microstructure and property of cobalt substituted bismuth ferrite thin films

Multiferroic BiFe_0.95Co_0.05O₃ thin films were fabricated on Pt/Ti/SiO₂/Si substrates at various temperatures by pulsed laser deposition. It was found the deposition temperature had great effects on phase purity, orientation, microstructure and multiferroic properties of these films. The optimized deposition temperature was close to 600?°C. Polarization–electric field (P–E) and magnetization–magnetic field (M–H) hysteresis loops at room temperature were observed simultaneously in the films fabricated at 600?°C. The remnant polarization, coercive electric field (P _r , E _c ) and the remnant magnetization, coercive magnetic field (M _r , H _c ) of the films deposited at 600?°C were (0.95?μC/cm², 31?kV/cm) and (0.59?emu/cm³, 130 Oe), respectively. These results might have implications for further investigations on high quality BiFe_0.95Co_0.05O₃ multiferroic films.     

Complexes of some rare earth metal ions of the mesogenic Schiff-base,N,N′-di-(4′-octyloxybenzoatesalicylidene)-l″,8″-diamino-3″,6″-dioxaoctane: Synthesis and spectral studies

A mesogenic Schiff-base, N,N′-di-(4′-octyloxybenzoatesalicylidene)-l″,8″-diamino-3″,6″-dioxaoctane; H₂dobsdd (H₂L³), that nematogenic mesophase was synthesized and its structure studied by elemental analysis and FAB mass, NMR and IR spectra. The Schiff-base, H₂L³, upon condensation with hydrated lanthanide(III) nitrates, yields Ln^III complexes of the general composition [Ln₂(L³H₂)₃(NO₃)₄](NO₃)₂, where Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy and Ho. The IR and NMR spectral data imply a bi-dentate of the Schiff-base through two phenolate oxygens in its zwitterionic form (as L³H₂) to the Ln^III ions, rendering the overall geometry of the complexes to seven-coordinated polyhedron — possibly distorted mono-capped octahedron. Among the metal complexes, only that of La^III and Gd^III are found to be mesogenic.