Crystal growth and characterization of potassium(I)-doped tetrakis(thiourea)nickel(II) chloride

The influence of alkali metal potassium(I)-doping on the properties of tetrakis(thiourea)nickel(II) chloride crystals has been investigated. The variation in the intensity observed in powder X-ray diffraction (XRD) of doped specimen and slight shifts in vibrational frequencies confirm the lattice stress as a result of doping. Surface morphological changes due to doping of the alkali metal are observed by scanning electron microscopy. The incorporation of K(I)- into the crystal lattice was confirmed by energy dispersive X-ray spectroscopy. Lattice parameters are determined by single crystal XRD analysis. The thermogravimetric and differential thermal analysis studies reveal the purity of the materials and no decomposition is observed up to the melting point. The crystal is further characterized by UV–Vis and Kurtz powder technique.     

Effect of magnesium doping on the properties and crystalline perfection of bis(thiourea)zinc(II) chloride crystals

In this article, the effect of magnesium doping on the properties of bis(thiourea)zinc(II) chloride (BTZC) crystals has been described. The incorporation of Mg(II) into the crystal lattice was confirmed by energy dispersive X-ray spectroscopy and quantified by inductively coupled plasma technique. The powder X-ray diffraction and FT-IR spectral analyses indicate that the crystal undergoes considerable stress as result of doping. SEM studies of pure and doped samples indicate the formation of structural defect centers in BTZC crystals. The TG?CDTA studies reveal the purity of the materials, and no decomposition is observed up to the melting point. Improved crystalline perfection by doping is observed by high-resolution X-ray diffraction. High transmittance is observed, and the cutoff ?? is ~295?nm.     

Alkali metal intercalated fullerene-like MS(2) (M = W, Mo) nanoparticles and their properties

Layered metal disulfides-MS(2) (M = Mo, W) in the form of fullerene-like nanoparticles and in the form of platelets (crystallites of the 2H polytype) have been intercalated by exposure to alkali metal (potassium and sodium) vapor using a two-zone transport method. The composition of the intercalated systems was established using X-ray energy dispersive spectrometer and X-ray photoelectron spectroscopy (XPS). The alkali metal concentration in the host lattice was found to depend on the kind of sample and the experimental conditions. Furthermore, an inhomogeneity of the intercalated samples was observed. The product consisted of both nonintercalated and intercalated phases. X-ray diffraction analysis and transmission electron microscopy of the samples, which were not exposed to the ambient atmosphere, showed that they suffered little change in their lattice parameters. On the other hand, after exposure to ambient atmosphere, substantial increase in the interplanar spacing (3-5 A) was observed for the intercalated phases. Insertion of one to two water molecules per intercalated metal atom was suggested as a possible explanation for this large expansion along the c-axis. Deintercalation of the hydrated alkali atoms and restacking of the MS(2) layers was observed in all the samples after prolonged exposure to the atmosphere. Electric field induced deintercalation of the alkali metal atoms from the host lattice was also observed by means of the XPS technique. Magnetic moment measurements for all the samples indicate a diamagnetic to paramagnetic transition after intercalation. Measurements of the transport properties reveal a semiconductor to metal transition for the heavily K intercalated 2H-MoS(2). Other samples show several orders of magnitude decrease in resistivity and two- to five-fold decrease in activation energies upon intercalation. These modifications are believed to occur via charge transfer from the alkali metal to the conduction band of the host lattice. Recovery of the pristine compound properties (diamagnetism and semiconductivity) was observed as a result of deintercalation.     

Os(VIII) doping effects on the properties and crystalline perfection of potassium hydrogen phthalate (KHP) crystals

The effect of dopant, Os(VIII) on the growth process, crystalline perfection and properties of potassium hydrogen phthalate (KHP) single crystals grown by a slow evaporation solution growth technique has been investigated. The XRD analysis of black-colored doped specimen reveals slight structural changes as a result of doping. The SEM images exhibit defect centers and crystal voids. The complex formation of KHP with Os(VIII) is evidenced by the considerable shift in λ_max of the doped specimen and enhanced fluorescence intensity is observed by doping. Differential scanning calorimetry (DSC) and TG-DTA studies reveal the purity of the sample and no decomposition is observed up to the melting point. The high resolution X-ray diffraction (HRXRD) studies used to evaluate the crystalline perfection reveal some features on the capability of accommodating the dopant in the crystalline matrix. The diffraction curve (DC) patterns indicate that the high valence transition metal predominantly occupies the interstitial positions and the doping depresses the second harmonic generation (SHG) efficiency owing to the deterioration of crystalline perfection disturbing the charge transfer and nonlinearity.     

Effect of zinc(II) doping on thermal and optical properties of potassium hydrogen phthalate (KHP) crystals

The influence of doping the transition metal Zn(II) on potassium hydrogen phthalate (KHP) crystals has been studied. A close observation of FT-IR and XRD profiles of doped and undoped samples reveals some minor structural variations. It appears that the crystal undergoes considerable lattice stress as a result of doping the bivalent zinc. Furthermore, the possibility of cation vacancies aroused owing to the substitution of K¹⁺ by Zn²⁺ could result in a defective crystal system. Energy dispersive spectra reveal the incorporation of Zn(II) in the crystalline matrix of KHP crystals. Differential scanning calorimetry (DSC) and TG-DTA studies reveal the purity of the sample and no decomposition is observed below the melting point. Small quantity additions of Zn(II) enhance the fluorescence intensity of KHP crystals. The doping results in morphological changes and significantly improves the second harmonic generation (SHG) efficiency of the host crystal.     

Electronic structure, magnetic ordering, and formation pathway of the transition metal oxide hydride LaSrCoO(3)H(0.7)

The role of the hydride anion in controlling the electronic properties of the transition metal oxide hydride LaSrCoO(3)H(0.7) is investigated theoretically by full potential DFT band structure calculation and experimentally by determination of the Neel temperature for three-dimensional magnetic ordering. The mechanism by which hydrogen is introduced into the solid is addressed by in situ X-ray diffraction studies of the formation of the oxide hydride, which reveal both a relationship between the microscopic growth of the observed oxide hydride order and the anisotropic broadening of the diffraction profile, and the existence of a range of intermediate compositions.     

The solubility of Co in TiO2 anatase and rutile and its effect on the magnetic properties

Co-doped anatase and rutile bulk-samples prepared by the sol-gel technique are found to be paramagnetic at room-temperature. Only further annealing in Ar/H₂ gas results in a ferromagnetic behavior. X-ray diffraction and electron-microscope studies reveal for low doping levels <4% the formation of Co-doped rutile samples and the formation of CoTiO₃ as a new phase. Co₃O₄ can be detected in anatase samples with Co doping levels ?4%. The observed Co oxides are reduced by Ar/H₂ to Co metal. The room-temperature ferromagnetism can therefore be traced back to a segregation of metallic Co.     

Influence of Vo(II) doping on the thermal and optical properties of magnesium rubidium sulfate hexahydrate crystals

We have prepared pure and divalent vanadyl ion-doped magnesium rubidium sulfate hexahydrate crystals by using slow evaporation solution growth technique. It is interesting to observe that Vo(II) doping influences the physical properties of MRSH. Presence of Vo(II) ions in the doped specimen was confirmed by energy dispersive spectroscopy and electron paramagnetic resonance spectroscopy. FTIR studies reveal that the doping of vanadium ion has not altered the basic structure of MRSH. Scanning electron microscope studies of doped sample reveals that structure defect centers are formed in the crystals. Gradual decomposition patterns were observed for pure and doped specimens in thermogravimetry and differential thermogravimetry. The grown crystals were also characterized by powder X-ray diffraction. The second harmonic generation efficiency tested using Kurtz powder technique is not influenced by the added dopant.     

Preparation and optical properties of ThO(2) and Eu-doped ThO(2) nanotubes by the sol-gel method combined with porous anodic aluminum oxide template

In this paper, we report the synthesis of thorium oxide and Eu-doped thorium oxide nanotubes for the first time using the sol-gel method in porous anodic aluminum oxide template. Transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy were applied to characterize the morphology and structure of the as-prepared nanotubes. It has been demonstrated that Eu(3+) ions were homogeneously doped into the ThO(2) crystal lattice. The optical properties resulting from Eu-doped products were investigated by means of photoluminescence spectroscopy. Strong visible light emissions were observed at low doping concentration, and the luminescent intensity decreased at high doping concentration. The luminescent centers were concluded to be the Eu(3+) ions in the cubic (O(h)) sites rather than the C(3v) sites, which accounted well for the decrease of luminescent intensity at high doping concentration.     

Synthesis,structural studies and bio-activity of some metal(II) complexes with glyoxal salicylaldehyde acyldihydrazones

Complexes of the type [M(gssdh)]Cl and [M(gspdh)]Cl, where M?=?Co(II), Ni(II), Cu(II), Zn(II) and Cd(II), Hgssdh?=?glyoxal salicylaldehyde succinic acid dihydrazone and Hgspdh?=?glyoxal salicylaldehyde phthalic acid dihydrazone, have been synthesized and characterized by elemental analyses, molar conductance, magnetic moments, electronic, ESR and IR spectra and X-ray powder diffraction studies. The metal complexes are insoluble in common organic solvents and are 1?:?1 electrolytes. The magnetic moment values and electronic spectra indicate a spin–free octahedral geometry for all Co(II), Ni(II) and Cu(II) complexes. ESR spectral parameters of Cu(II) complexes suggest an elongated tetragonally–distorted octahedral stereochemistry around copper. Both ligands are monobasic hexadentate ligands coordinating through three >C=O, two >C=N– and a deprotonated phenolate group to the metal. X-ray powder diffraction parameters for three of the complexes correspond to an orthorhombic crystal lattice. The complexes show appreciable activity against various fungi and bacteria.     

Magnetic ordering in doped Cd(1-x)Co(x)Se diluted magnetic quantum dots

In this study, we report structural, vibrational, and magnetic data providing evidence of random ion displacement in the core of CdSe quantum dots on the Cd(2+) sites by Co(2+) ions (between x = 0 and 0.30). Structural evidence for core doping is obtained by analyzing the powder X-ray diffraction (pXRD), data which exhibits a linear lattice compression with increasing Co(2+) concentration, in accord with Vegard's law. Correlated with the pXRD shift, a hardening of the CdSe longitudinal optical phonon mode and a new local vibrational mode are observed which track Co(2+) doping concentration. Consistent with the observed core doping, superconducting quantum interference device (SQUID) measurements indicate a surprising increase for the onset of spin glass behavior by an order of magnitude over bulk Co:CdSe. Correlation of SQUID results, pXRD, and Raman measurements suggests that the observed enhancement of magnetic superexchange between Co(2+) dopant ions in this confined system arises from changes in the nature of coupling in size-restricted materials.     

Spectral, optical, and thermal studies of pure and Zn(II)-doped l-histidine hydrochloride monohydrate (LHHC) crystals

The influence of doping the transition metal Zn(II) on the growth, spectral, optical, and thermal properties of l-histidine hydrochloride monohydrate (LHHC) crystals grown by slow solvent evaporation method has been investigated. Structural characterizations of the grown crystals were carried out by single crystal X-ray diffraction analysis and it shows slight structural changes as a result of doping. The FT-IR spectral study reveals the presence of various functional groups and confirms the slight distortion of the structure of the crystals due to doping. The energy dispersive X-ray analysis reveals the incorporation of Zn(II) in the crystalline matrix of LHHC crystal. The UV?CVis spectral study was carried out to analyze the optical transmittance of the grown crystals and found that the transmittance is very high in the visible and UV regions for both pure and doped crystals. The second harmonic generation (SHG) for the grown crystals was confirmed by Nd:YAG laser. The scanning electron microscopy reveals the presence of defect centers and crystal voids. The thermal stability and purity of the grown crystals were analyzed by thermogravimetry, differential thermal analysis, and differential scanning calorimetry techniques.     

Syntheses and structures of Mn(II), Co(II), and Zn(II) complexes of 1,3-diterpyridyl-substituted p-tert-butylcalix[4]arene

The calix[4]arene-based podand which incorporates two terpyridine functions in 1,3-alternate positions with flexible propylene spacers at lower rim has been prepared and subjected to complexation studies with some transition metal ions. Single-crystal structures of Mn(II), Co(II), and Zn(II) complexes were determined by X-ray diffraction. These metal complexes are formed with a 2?:?1 ratio of metal and ligand. Coordination of each metal is five-coordinate distorted trigonal-bipyramidal geometry by three nitrogen atoms from a terpyridyl unit and two chloride atoms.     

Homo‐ and Heterodinuclear Helicates of Lanthanide(III), Zinc(II) and Aluminium(III) Based on 8‐Hydroxyquinoline Ligands

Homonuclear helicates with rare‐earth‐metal(III) ions or heteronuclear derivatives with rare‐earth‐metal and aluminium or zinc centres are obtained in alkali‐metal‐templated self‐assembly processes from isobutenylidene‐bridged homoditopic bis(2‐carbamido‐8‐hydroxyquinoline)‐derived ligands 1 ? H₂ and 2 ? H₂ or heteroditopic (8‐hydroxyquinoline)(2‐carbamido‐8‐hydroxyquinoline)‐derived ligands 3 ? H₂ and 4 ? H₂. Diamagnetic coordination compounds possess a high stability in organic solvents such as CDCl₃, [D₄]MeOH or [D₆]DMSO and can be well characterised by ¹H NMR spectroscopy by using methylene protons and the protons of the vinylic units of the ligand as stereochemical or symmetry probes, respectively. Some of the homonuclear complexes could be crystallised and were characterised by using X‐ray diffraction studies. The complexes adopt a triple‐stranded helical structure with a central templating cation encapsulated in their interior. An unusual orientation of the double bond of one spacer towards this cation is observed. The homo‐ and heterodinuclear helicates with ytterbium(III), neodymium(III) or erbium(III) of ligands 2 and 4 were of special interest owing to their near‐infrared (NIR) emitting properties, which were investigated depending on the lanthanide and on the encapsulated alkali‐metal cation.     

碱金属离子对Fe(phen)3/Y催化氧化性能的影响

采用自由配体法,将铁邻菲啰啉(Fe(phen)3)配合物封装在含有不同碱金属阳离子的Y型分子筛中,制备了系列Fe(phen)3/M-Y(M=Li+,Na+,K+和Cs+)催化剂.采用X射线衍射、红外光谱、紫外-可见光谱、热重-差热分析、电感耦合等离子原子发射光谱、N2吸附-脱附以及催化氧化反应考察了碱金属离子对Fe(phen)3/M-Y催化剂物化性质和催化氧化性能的影响.结果表明,交换有不同碱金属离子的Y型沸石中Fe(phen)3的封装量不同,而且Fe(phen)3在Y型沸石中的热稳定性随着碱金属离子半径的增加有所降低,其中Fe(phen)3/Li+-Y具有最高的配合物封装量和热稳定性能.在环己烷或苯乙烯氧化反应中,在较低的反应温度下,Fe(phen)3/K+-Y表现出最高的催化活性,而在较高的反应温度下,Fe(phen)3/Cs+-Y的催化活性最高,碱金属离子对Fe(phen)3/M-Y催化氧化性能的影响是电子效应、空间限制作用和扩散效应的综合结果.     

Synthesis, spectral characterization and biological activities of Mn(II) and Co(II) complexes with benzyloxybenzaldehyde-4-phenyl-3-thiosemicarbazone

Mn(II) and Co(II) complexes of benzyloxybenzaldehyde-4-phenyl-3-thiosemicarbazone have been synthesized and characterized by the investigations of electronic and EPR spectra and X-ray diffraction. Based on the spectral studies, an octahedral geometry is assigned for the Mn(II) and Co(II) complexes. X-ray powder diffraction studies reveal that Mn(II) and Co(II) complexes have triclinic crystal lattices. The unit cell parameters of the Mn(II) complex are a=11.0469 ?, b=6.2096 ?, c=7.4145 ?, α=90.646°, β=95.127°, γ=104.776°, V=489.7 ?(3) and those of Co(II) complex are a=9.3236 ?, b=10.2410 ?, c=7.8326 ?, α=90.694°, β=99.694°, γ=100.476°, V=724.2 ?(3). When the free ligand and its metal complexes are subjected to antibacterial activity, the metal complexes are proved to be more active than the ligand. However with regard to in vitro antioxidant activity, the ligand exhibits greater antioxidant activity than its metal(II) complexes.     

Optical and photocatalytic properties of heavily F(-)-doped SnO2 nanocrystals by a novel single-source precursor approach

Heavily F-doped SnO(2) nanocrystals were successfully prepared by a novel synthetic approach involving low-temperature oxidation of a Sn(2+)-containing fluoride complex KSnF(3) as the single-source precursor with H(2)O(2). The F-doped SnO(2) powder was characterized by powder X-ray diffraction, TG-MS, BET surface area, diffuse reflectance spectroscopy, XPS, PL, FTIR spectroscopy, Raman spectroscopy, EPR spectroscopy, SEM, and TEM. Broadening of the diffracted peaks, signifying the low crystallite size of the products, was quite evident in the powder X-ray diffraction pattern of SnO(2) obtained from KSnF(3). It was indexed in a tetragonal unit cell with lattice constants a = 4.7106 (1) ? and c = 3.1970 (1) ?. Agglomeration of particles, with an average diameter of 5-7 nm, was observed in the TEM images whose spotwise EDX analysis indicated the presence of fluoride ions. In the core level high-resolution F 1s spectrum, the peak observed at 685.08 eV was fitted by the Gaussian profile yielding the fluoride ion concentration to be 21.23% in the SnO(2) lattice. Such a high fluoride ion concentration is reported for the first time in powders. SnO(2):F nanocrystals showed greater thermal stability up to 300 °C when heated in a thermobalance under flowing helium, after which generation of small quantities of HF was observed in the TG coupled mass spectrometry analysis. The band gap value, estimated from the Kubelka-Munk function, showed a large shift from 3.52 to 3.87 eV on fluoride ion doping, as observed in the diffuse reflectance spectrum. Such a large shift was corroborated to the overdoped situation due to the Moss-Burstein effect with an increase in the carrier concentration. In the photoluminescence (PL) spectrum, SnO(2):F nanocrystals exhibited a broad green emission arising from the singly ionized oxygen vacancies created due to higher dopant concentration. The evidence for singly ionized vacancies was arrived from the presence of a signal with a g value of 1.98 in the ESR spectrum of SnO(2):F at room temperature. The disordered nature of the rutile lattice and the enormous oxygen vacancies created due to fluoride ion doping were evident from the broad bands observed at 455, 588, and 874 cm(-1) in the room-temperature Raman spectrum of SnO(2):F. As the consequence of the oxygen vacancies, F-doped SnO(2) was examined for the function as a photocatalyst in the degradation of aqueous RhB dye solution under UV irradiation. A very high photocatalytic efficiency was observed for the F-doped SnO(2) nanocrystals as compared to pure SnO(2). The BET surface area of pure SnO(2) was quite high (207.81 m(2)/g) as compared to the F-doped SnO(2) nanocrystals (45.16 m(2)/g). Pore size analysis showed a mean pore diameter of 1.97 and 13.97 nm for the pure and doped samples. The increased photocatalytic efficiency was related to the very high concentration of oxygen vacancies in SnO(2) induced by F doping.     

Two-phase synthesis of colloidal annular-shaped Ce(x)La(1-x)CO3OH nanoarchitectures assembled from small particles and their thermal conversion to derived mixed oxides

Undoped and cerium doped LaCO(3)OH annular-shaped nanoarchitectures with high specific surface area have been fabricated via the thermolysis of Ce(x)La(1-x)(oleate)(3) (x = 0-20 mol %) complexes in a toluene-water system containing tert-butylamine/oleylamine. The products exhibit 400 nm-sized monodisperse annular-shaped nanoarchitectures, which are constituted of 3-5 nm-sized primary particles. A possible mechanism of the reaction of Ce(x)La(1-x)(oleate)(3) and tert-butylamine for the formation of annular-shaped Ce(x)La(1-x)CO(3)OH nanoarchitectures is proposed. The thermal conversion of Ce(x)La(1-x)CO(3)OH to Ce(x)La(1-x)(CO(3))O(2) at 600 °C, to Ce(x)La(1-x)(OH)(3) at 800 °C, final to (Ce(x)La(1-x))(2)O(3-δ) at 900 °C were employed, while the original morphology was essentially unchanged. The dopant concentration was varied from 5 to 20 of cerium ions per LaCO(3)OH nanoparticle. The X-ray diffraction (XRD) results reveal that the cerium dopant could enter easily into the LaCO(3)OH structural lattice, whereas copper could unlikely enter into their lattice because of their large ionic radius difference. The cerium oxidation state was controlled by changing doping concentration. The X-ray photoelectron spectroscopy (XPS) results reveal that only one Ce(3+) oxidation state is in the as-synthesized Ce(x)La(1-x)CO(3)OH samples with cerium concentration ranging from 5 to 20 mol %, whereas both 3+ and 4+ ones coexisted in 20 mol % Ce:LaCO(3)OH structure. Remarkable luminescence emission intensity enhancement of 1.5-9.0 times were observed for Ce(x)La(1-x)CO(3)OH samples with cerium concentration ranging from 5 to 20 mol %, after doping with an undoped LaCO(3)OH.     

Studies on Co(II) and Co(III) complexes of di-2-pyridyl ketone N(4)-cyclohexyl and N(4)-phenyl thiosemicarbazones

Six new Co(II) and Co(III) complexes (1–6) of di-2-pyridyl ketone N(4)-cyclohexyl thiosemicarbazone (HL¹) and di-2-pyridyl ketoneN(4)-phenyl thiosemicarbazone (HL²) have been synthesized and spectrochemically characterized. HL¹ is newly synthesized and has been structurally characterized by single crystal X-ray diffraction studies, while HL² has been previously reported. HL¹ crystallizes into a monoclinic lattice with the space group P2₁. The complexes are characterized by magnetic, EPR, NMR and other spectroscopic studies. The EPR spectra of the paramagnetic complexes reveal axial features with eight hyperfine lines clearly resolved in the perpendicular region.     

2-(1H-pyrazol-3-yl)pyrazine: a polytopic N-donor ligand used to construct Cu-[2+2] molecular grid: synthesis,structure, and magnetic properties

Herein, we present a new polytopic N-donor, which is used to construct a metal–organic compound. The resulting metal–organic compound, Cu₄(L)₆(NO₃)₂ (HL=(1H-pyrazol-3-yl)pyrazine) (1), is synthesized by the hydrothermal reaction of Cu(NO₃)₂ and HL (ratio: 1?:?1). Single-crystal X-ray diffraction shows that 1 comprises a Cu-[2+2] molecular grid. Magnetic studies reveal antiferromagnetic interactions, interpreted by a simplified dinuclear mode.