Synthesis,characterization and properties of polyaniline doped with transition metal substituted silicotungstate

Polyaniline hybrid material doped with transition metal mono-substituted silicotungstate β₂-K₆[SiW₁₁M(H₂O)O₃₉]?·?xH₂O (M?=?Mn²⁺, Co²⁺, Cu²⁺, Fe²⁺) were prepared for the first time. Their scanning electron microscopy (SEM), infrared (IR), UV–Vis, and X-ray diffraction (XRD) patterns confirm the existence of Keggin anions and form the space reticular structure. The material exhibits excellent proton conduction, its proton conductivity is 9?×?10^?2?s?cm^?1 at room temperature (20°C).     

Keggin结构钴取代硅钨酸盐聚苯胺掺杂材料的合成及性质

以Keggin结构钴取代杂多硅钨酸盐异构体α，β_i-K_6-nH_n[SiW₁₁Co(H₂O)O₃₉]·xH₂O( β_i=β₁，β₂，β₃)为掺杂剂，采用固相合成法制备了4种聚苯胺掺杂材料。用元素分析、红外光谱、紫外-可见光谱、SEM、X-射线粉末衍射、热重分析等对材料进行了表征，测定了材料的热稳定性、荧光性和导电性。实验结果表明：合成的掺杂态聚苯胺新材料具有较好的热稳定性、荧光性和导电性，室温电导率为7.5 × 10^-2 S·cm^-1，每种掺杂材料都有一个荧光发射峰，其发光中心来自于掺杂态聚苯胺极化子能带与价带之间的跃迁。     

Synthesis,spectroscopic properties and crystal structure of organophosphoryl polyoxotungstate α-[Bu4N]3H[PhCH2P(O)]2SiW11O39

Reaction of the monovacant heteropolyanions α-[SiW₁₁O₃₉]^8? with PhCH₂PO(OH)₂ leads to the formation of the organophosphoryl derivative α-[Bu₄N]₃H[PhCH₂P(O)]₂SiW₁₁O₃₉ (1). Single-crystal X-ray diffraction analysis shows that the crystal is monoclinic with space group P2₁ /n and the unit cell parameters: a?=?14.386 (3)?Å, b?=?27.015 (5)?Å, c?=?25.480 (5)?Å, α?=?90°, β?=?91.44 (3)°, γ?=?90°, V?=?9899 (3)?ų. Z?=?4, D _c?=?2.467?g?cm^?1, λ (Mo-Kα)?=?0.071073?nm, R ₁?=?0.0638, wR ₂?=?0.1364. The hybrid anion consists of an α-[SiW₁₁O₃₉]^8? framework on which two equivalent organophosphoryl groups are grafted through P?O?W bridges; each of the two PhCH₂P(O) groups are connected to two terminal oxygen atoms belonging to a triad and a diad, respectively.     

Synthesis and Crystal Structure of K6.5H4.5[CeK2(SiW11O39)2]·26H2O

The title compound, K_6.5H_4.5[CeK₂(SiW₁₁O₃₉)₂]·26H₂O was prepared and its structure characterized by IR and single crystal X-ray structural analysis. It belongs to triclinic, space group P1 with a = 12.719(3) Å, b = 16.658(4) Å, c = 23.075(6) Å, α = 94.41(2)°, β = 98.90(2)°, γ = 92.40(2)°; V = 4809(2) Å^?3, Z = 2, Dc = 4.344 g cm^?3, μ = 27.170 mm^?1, F (000) = 5519. The results show that the cerium and two potassium atoms link the two anionic units SiW₁₁O^8? ₃₉ through O-Ce-O and O-K-O bridges and construct the double 1 : 11 series heteropolytungstate. Furthermore, cerium is coordinated to eight oxygen atoms (four O_c and four O_b) from two tetradentate SiW₁₁O^8? ₃₉ ligands forming a square anti-prism. The coordination numbers for K1 and K2 are 8 and 7, respectively.     

A new organic-inorganic hybrid material constructed from Keggin polyanion and transition metal complexes: [Co(2,2′-bipy)3]1.5[SiWVWVI 11O40Co(2,2′-bipy)2(H2O)] · 0.5H2O

A new organic-inorganic hybrid compound constructed from Keggin-type polyanion clusters and transition metal complexes, [Co(2,2′-bipy)₃]_1.5[SiW^VW^VI ₁₁O₄₀Co(2,2′-bipy)₂(H₂O)] ·?0.5H₂O (1), has been hydrothermally prepared and characterized by elemental analysis, IR, UV–Vis, TG-DTA and single crystal X-ray diffraction. Compound 1 crystallized in the monoclinic system, space group C2/c, a =?46.995(15), b =?14.487(5), c =?26.205(9)Å, β =?90.000(0)°, V =?17841(10)ų, Z =?4. Compound 1 contains a [SiW^VW^VI ₁₁O₄₀Co(2,2′-bipy)₂(H₂O)]^3? polyoxoanion in which [Co(2,2′-bipy)₂(H₂O)]²⁺ is covalently bonded to the α-Keggin-type heteropolyanion [SiW^VW^VI ₁₁O₄₀]^5? via a terminal oxygen.     

Spectrothermal properties and crystal structure of a polynuclear µ-squarato(O1,O3)bis(monoethanolamine)copper(II) complex, [Cu(µ-sq)(mea)2] n

Catena-poly-trans-µ-(squarato-O¹,O³)bis(monoethanolamine)copper(II), [Cu(µ-C₄O₄)(C₂H₇NO)₂] _n has been prepared and characterized by elemental analysis, IR, UV-Vis, EPR, thermal analysis and single crystal X-ray diffraction. The compound crystallizes in the triclinic system, space group P-1, with a?=?5.1435(7), b?=?7.2931(10), c?=?7.5198(11)?Å, α?=105.940(11)°, β?=?98.731(11)°, γ?=?101.981(11)° and Z?=?1. The structure contains chains of squarato-O¹,O³-bridged polynuclear copper(II) units. The configuration around each copper is distorted octahedral with two nitrogen and two oxygen atoms of two bidentate neutral monoethanolamine (N,?O) ligands and two oxygen atoms of two squarato (μ-O¹,O³) ligands. These chains are held together by an extensive three-dimensional network of N-H?···?O type intermolecular hydrogen bonds and van der Waals forces. The IR, UV-Vis and EPR spectra, magnetic study and thermal analysis of the complex are described.     

Development of a Sustainable Resource Based Conducting Composite of Polyaniline‐Poly(esteramideurethane)

Polymers synthesized from coconut oil as a precursor find scarce applications. Polyesteramide urethane synthesized from coconut oil, a natural resource, is a dough‐like material, unusable in our study. Upon loading with polyaniline it becomes tough and flexible. Composites of ClO₄ ^? doped polyaniline with coconut oil based poly(esteramide urethane) (CPEAU) were prepared by a solution blending technique, using different ratios of polyaniline(2 wt%, 4 wt% and 8 wt%). The composites were further characterized by FT‐IR, DSC, TGA, XRD, and SEM. Conductivity was found to be in the range 2.5×10^?5?5.7×10^?4 S cm^?1. The composite was found to show weak hydrogen bonding interactions between PANI and CPEAU at 8 wt% loading.     

Emissions of biogenic volatile organic compounds from Fraxinus excelsior and Quercus robur under ambient conditions in Flanders (Belgium)

A dynamic branch enclosure system was used to measure emission rates of biogenic volatile organic compounds (BVOCs) from two common European tree species: Fraxinus excelsior and Quercus robur under ambient conditions in Flanders (Belgium). Both tree species were studied for seasonal variability of BVOC emission rates under natural biotic stress (infestations). Emissions were normalized at standard conditions of temperature and photosynthetic active radiation (PAR) (30°C and 1000?µmol?m^?2?s^?1, respectively). Emission rates from Fraxinus excelsior were highest in May (9.56?µg?g_DW ^?1?h^?1) and lowest in October (1.17?µg?g_DW ^?1?h^?1). This tree species emitted (Z)-β-ocimene, (E)-β-ocimene and α-farnesene during the entire measurement period and additionally isoprene only in May. Quercus robur showed isoprene emission variations according to the seasonal cycle with rates of 30, 106 and 29?µg?g_DW ^?1?h^?1 in May, August and October, respectively. Apart from isoprene, (E)-β-ocimene and β-caryophyllene were emitted through the entire experimental period.     

Metal–oxo cluster-supported transition metal complexes: hydrothermal synthesis and characterization of [{Cu(phen)2}2SiW12O40]

A new neutral α-Keggin polyoxometalate, [{Cu(phen)₂}₂SiW₁₂O₄₀] (1) (phen?=?1,10-phenanthroline) was hydrothermally synthesized and characterized by IR, TG and single-crystal X-ray diffraction. The compound is monoclinic, space group P2₁/c with a?=?26.065(5), b?=?11.867(2), c?=?23.385(5)?Å, β?=?113.78(3)°, V?=?6619?ų, Z?=?4. X-ray analysis showed that both [Cu(phen)₂]²⁺ units are supported on the α-Keggin polyoxoanion [SiW₁₂O₄₀]^4? via the surface bridging and terminal oxygen atoms of two non-adjacent WO6 octahedra; these show unusual coordination environments. One Cu ion displays distorted trigonal bipyramidal geometry and the other square pyramidal. The unusual coexistence of complexes with different geometries is most likely caused by steric effects involving surface oxygen atoms of the heteropolytungstate and phen, which prevent the presence of a sixth coordinating atom. Weak π–π stacking interactions between phen groups give a 1D chain-like structure and hydrogen bonds are responsible for extended 2D and 3D motifs in the crystal.     

Preparation of β-cyclodextrin-polyaniline complex in supercritical CO2

A method is proposed to prepare β-cyclodextrin (β-CD)/polyaniline (PANI) inclusion complex. In this route, benzoyl peroxide (BPO, the oxidant) is first encapsulated into the cavity of β-CD. Aniline is then carried into the cavity of β-CD by supercritical (SC) CO₂, which polymerizes in situ to form inclusion complex. The product is characterized by FT-IR, UV-Vis, ¹H NMR and XRD techniques. The results suggest that the columnar inclusion complexes may be formed.     

Biological and phytochemical studies on Capparis decidua (Forssk) Edgew from Cholistan desert

Abstract

The present work deals with the biological and phytochemical studies on Capparis decidua (Forssk) Edgew from Cholistan desert of Pakistan. Aerial and floral parts of C. decidua were collected and dried under shade. Powdered materials of each part of C. decidua were extracted with methanol separately, followed by phytochemical studies. Hexane fraction of aerial parts of the C. decidua obtained after solvent-solvent extraction was purified through repeated column chromatography by increasing order of polarity. Four compounds were purified and identified as simiarenol (1), lupeol (2), taraxerol (3) and β-sitosterol (4). Simiarenol and lupeol were isolated for the first time from genus Capparis. The structures of these compounds were established by comparing the spectroscopic data (¹H NMR, ¹³C NMR, IR, UV & Mass spectrometry) reported in literature. The structure of 1 was further confirmed by XRD analysis. Anti-bacterial activities of crude methanolic extracts were determined against 13 bacterial strains (MIC 250-1000?μg/mL). α-Glucosidase and urease inhibitory activities of pure compounds were also determined. Compounds 1, 2 and 4 showed α-glucosidase inhibition with IC₅₀ at 96.12?±?0.12, 65.28?±?0.13 and 128.14?±?0.17?μM, respectively.     

Synthesis,crystal structure and non-linear optical properties of a new cyanide-containing compound

Reaction of K₃[Fe(CN)₆], NiCl₂ and diethylenetriamine (dien) resulted in the formation of a cyanide-containing heterometallic compound [Ni(dien)₂]₂[Fe(CN)₆]·4H₂O 1. The structure consists of two octahedral [Ni(dien)₂]²⁺ cations, one octahedral [Fe(CN)₆]^4? anion and four crystallization water molecules, which are held together by hydrogen-bonding interactions. Its TG curve exhibits two stages of mass loss. Compound 1 in DMF solutions has a very strong third-order non-linear optical (NLO) behavior with an absorption coefficient and refractive index α₂?=?1.10?×?10^?11?m?w^?1, n ₂?=??3.05?×?10^?19?m²?w^?1, respectively, and third-order NLO susceptibility χ⁽³⁾ 4.34?×?10^?13?esu.     

Stability of gold(I) glycinate complexes in aqueous solution

The stepwise substitution equilibrium AuCl ₂ ^? +iX^?=AuCl_2?i X _i ^? +iCl^?, β_i, where X^? is the glycinate ion (H₂N-CH₂-COO^?), i = 1 or 2, at 25°C in an aqueous solution with I = 1.0 mol/L (NaCl) has been studied pH-metrically. The corresponding constants are logβ₁ = 3.60 ± 0.10, and logβ₂ = 6.2 ± 0.2.     

Preparation and characterization of PVC/PANI conductive composite with extremely low percolation threshold

Aniline was polymerized in the presence of poly(vinyl chloride) (PVC) powders in hydrochloric acid to in situ prepare poly(vinyl chloride)/polyaniline (PVC/PANI) composite particles. UV‐vis spectra and FT‐IR spectra indicate PANI in PVC/PANI composite particles possessed a higher oxidation state with decreased aniline content in reactants. Both conductivity and impact strength of the dodecylbenzenesulfonic acid (DBSA) doped PANI composites (PVC/PANI‐DBSA), which were compression molded from the in situ prepared PVC/PANI particles, increase with the pressing temperature and decrease with the increase of DBSA doped PANI (PANI‐DBSA) loading. An excellent electric conductivity of 5.06 × 10^?2 S/cm and impact strength of 0.518 KJ/m² could be achieved for the in situ synthesized and subsequently compression molded composite. Copyright © 2004 John Wiley & Sons, Ltd.     

Photocatalytic activity of polyaniline/Fe-doped TiO2 composites by in situ polymerization method

This study was focused on the photocatalytic activity of polyaniline (Pani)/iron doped titanium dioxide (Fe–TiO₂) composites for the degradation of methylene blue as a model dye. TiO₂ nanoparticles were doped with iron ions (Fe) using the wet impregnation method and the doped nanoparticles were further combined with Pani via an in situ polymerization method. For comparison purposes, Pani composites were also synthesized in the presence undoped TiO₂. The photocatalyst and the composites were characterized by standard analytical techniques such as FTIR, XRD, SEM, EDX and UV–Vis spectroscopies. Fe–TiO₂ and its composites exhibited enhanced photocatalytic activity under ultraviolet light irradiation. Improved photocatalytic activity of Fe–TiO₂ was attributed to the dopant Fe ions hindering the recombination of the photoinduced charge carriers. Pani/Fe–TiO₂ composite with 30?wt.% of TiO₂ nanoparticles achieved 28% dye removal and the discoloration rate of methylene blue for the sample was 0.0025?min^?1. FTIR, XRD, SEM, EDX and UV–Vis spectroscopies supported the idea that Fe ions integrated into TiO₂ crystal structure and Pani composites were successfully synthesized in the presence of the photocatalyst nanoparticles. The novelty of this study was to investigate the photocatalytic activity of Pani composites, containing iron doped TiO₂ and to compare their results with that of Pani/TiO₂.     

Synthesis and characterization of polyaniline microfibers by utilizing H4SiW12O40/polyacrylamide microfibers seeding template method

In this paper, polyaniline (PANI) microfibers with average diameter of 250 nm were synthesized by utilizing H₄SiW₁₂O₄₀/polyacrylamide (HPA/PAM) microfibers seeding template method. The PANI microfibers were characterized by element analyses, FT-IR spectra, X-ray diffraction pattern (XRD), and Scanning electron micrograph (SEM). The microfibers seeding template significantly affected the fibrous morphology of the resulting PANI. However, the diameter of the PANI microfibers was almost not affected by the diameter of the microfibers seeding template in the experimental range. In addition, the conductivity of the PANI microfibers was also investigated. The result showed that the best conductivity of the PANI microfibers doped with H₄SiW₁₂O₄₀ was 27.1 S/cm.     

环丙沙星-钨硅多金属氧酸盐的制备及热分解动力学

A new polyoxometalate （CPFX·HCl）3H4SiW12O40·10H2O was prepared from ciprofloxacin hydrochloride and H4SiW12O40·nH2O in aqueous solution, and characterized by elemental analysis, IR spectra and DTA-TG-DTG techniques. The IR spectrum confirmed the presence of Keggin structure and the characteristic functional group for ciprofloxacin in the compound. The TG-DTA-DTG curves showed that its thermal decomposition was a four-step process consisting of simultaneous collapse of Keggin type structure. The residue of decomposition was the mixture of WO3 and SiO2, confirmed by X-ray diffraction and IR spectroscopy. The decomposition mechanism and nonisothermal kinetic parameters of the polyoxometalate were obtained from an analysis to the TG-DTG curves by the single scanning methods （the Achar method and Coats-Redfern method） and the multiple scanning methods （the Kissinger method, Flynn-Wall-Ozawa method and Starink method）. The results indicate that the kinetic equationswith parameters describing the thermal decomposition reaction are dα/dt=6.65×10^6[3（1-α）^2/3]e^-10495.5/T with E=87.26 kJ/mol and A=6.65×10^6 s^-1 for the second step,dα/dt=7.01×10^9（1-α）e^-18770.7/T with E=156.06 kJ/mol and A=7.01×10^9 s^-1 for the third step,dα/dt=9.77×10^43[（1-α）^2]e^-88980.0/T with E=739.78 kJ/mol and A=9.77×10^43 s^-1 for the fourth step.     

Voltammetry of Dissolved Iron(III)–Nitrilotriacetate–Hydroxide System in Water Solution

The investigation of the dissolved iron(III)–nitrilotriacetate–hydroxide system in the water solution (I=0.1 mol L^?1 in NaClO₄; pH 8.0±0.1) using differential pulse cathodic voltammetry, cyclic voltammetry, and sampled direct current (DC) polarography, was carried out on a static mercury drop electrode (SMDE). The dissolved iron(III) ion concentrations varied from 2.68×10^?6 to 6×10^?4 mol L^?1 and nitrilotriacetate concentrations were 1×10^?4 and 5×10^?4 mol L^?1. By deconvoluting of the overlapped reduction voltammetric peaks using Fourier transformation, four relatively stable, dissolved iron(III) complex species were characterized, as follows: [Fe(NTA)₂]^3?, mixed ligand complexes [FeOHNTA]^? and [Fe(OH)₂NTA]^2?, showing a one‐electron quasireversible reduction, and binuclear diiron(III) complex [NTAFeOFeNTA]^2?, detected above 4×10^?4 mol L^?1 of the added iron(III) ions, showing a one‐electron irreversible reduction character. The calculations with the constants from the literature were done and compared with the potential shifts of the voltammetric peaks. Fitting was obtained by changing the following literature constants: log β₂([Fe(NTA)₂]^3?) from 24 to 27.2, log β₁([FeNTA]^?) from 8.9 to 9.2, log β₂([Fe(NTA)₂]^4?) from 11.89 to 15.7 and log β₂([Fe(OH)₂NTA]^3?) from 15.63 to 19. The determination of the electrochemical parameters of the mixed ligand complex [FeOHNTA]^?, such as: transfer coefficient (α), rate constant (k_s) and formal potential (E°') was done using a sampled DC polarography, and found to be 0.46±0.05, 1.0±0.3×10^?3 cm s^?1, and ?0.154±0.010 V, respectively. Although known previously in the literature, these four species have now for the first time been recorded simultaneously, i.e. proved to exist simultaneously under the given conditions.     

Polyimide/polyoxometalate copolymer thin films: synthesis,thermal and dielectric properties

A mono‐lancunary keggin‐type decatungstosilicate (SiW₁₁) polyoxometalate (POM) modified by γ‐aminopropyltriethoxysilane (KH550) was incorporated into polyimide (PI) through copolymerization. Nuclear magnetic resonance (NMR), fourier transition infrared spectroscopy (FTIR), and wide angle X‐ray diffraction (WAXD) were used to characterize the structure and composition of the polyoxometalate–organosilane hybrid (SiW₁₁KH550) and PI/SiW₁₁KH550 copolymers. The differential scanning calorimetry (DSC) studies indicate that the glass transition temperature (T_g) of PI/SiW₁₁KH550 copolymers increases from 330°C (for neat PI) to 409°C (for the copolymer sample with 10 wt% of SiW₁₁KH550). Dielectric measurement showed that both the dielectric constant and the dielectric loss for the copolymer thin films decreased with the increase in SiW₁₁KH550 content, and the dielectric constant and dielectric loss values decreased to 2.1 and 3.54 × 10^?3, respectively, for the copolymer sample with 10 wt% of SiW₁₁KH550. The incorporation of SiW₁₁KH550 into polymer matrices is a promising approach to prepare PI films with a low dielectric constant and low dielectric loss. Copyright © 2009 John Wiley & Sons, Ltd.