Electrochemical synthesis and electronic properties of poly(3,4-dibutyl-α-terthiophene)

Electrochemically prepared poly(3,4-dibutyl-α-terthiophene) has been investigated and the relationship between the electronic properties, the chemical structure of the monomer and the electrolyte used during the electropolymerization was studied. Doping studies were carried out with various electrolytes. We have electrochemically oxidized (p-doping) and reduced (n-doping) thin films of this polymer on platinum electrode under the same electrochemical conditions. We find that the films show a reversible oxidation wave yielding an electrically conducting polymer and a reversible reduction wave which is sensitive to the nature of the electrolyte. A value for the band gap derived electrochemically compares well with that obtained by optical absorption measurements and X-ray photoelectron spectroscopy. The electrical conductivity varies by 10¹² S cm⁻¹ between the doped and undoped states of the polymer. The temperature-independent magnetic susceptibility above 100 K is consistent with the conducting properties of this polymer. The electrochemically prepared material is compared with the chemically prepared one using the same monomer.     

Poly(phenylene sulfide–phenyleneamine–phenyleneamine) (PPSAA)—a soluble model for polyaniline

A novel nitrogen and sulfur containing polymer, the so-called poly(phenylene sulfide–phenyleneamine–phenyleneamine) (PPSAA) has been synthesized via a soluble precursor polymer through an acid-induced polycondensation reaction of N-(4-methylsulfinyl)phenylene-N′-phenyl-1,4-phenylenediamine. This high molecular weight compound is exceptionally soluble in common organic solvents such as THF, DMF and NMP. The close electronic relationship of PPSAA to polyaniline (PAni) is demonstrated by UV–Vis spectroscopy and cyclic voltammetry measurements on a model compound and on the polymer. First investigations on both the acid-type and the oxidative-type doping of the PPSAA are presented. Furthermore, the concepts for the build-up of nitrogen and sulfur containing polymers with hyperbranched- or step-ladder-type topology are briefly introduced.     

3′-Vinyl-2,2′:5′,2′'-terthiophene: synthesis,polymerization and copolymerization with styrene

A simple two-step synthesis of the previously unknown 3′-vinyl-2,2′:5′,2″-terthiophene from 2,3,5-tribromothiophene is described. The availability of 3′-bromo-2,2′:5′,2″-terthiophene described in this work should be useful for the synthesis of many other 3′-substituted polythiophenes. The preparation and some properties of poly(3′-vinyl-2,2′:5′,2″-terthiophene) and of a copolymer of 3′-vinyl-2,2′:5′,2″-terthiophene with styrene are reported.     

Poly(2,5-dialkoxy-p-phenylenebutadiynylene)s—Novel rigid conjugated polymers with liquid crystalline property

Novel rigid conjugated poly(p-phenylenebutadiynylene)s having long alkoxy side chains, octyloxy (C8), decyloxy (C10), and dodecyloxy (C12) at 2,5-positions of a phenylene unit, are synthesized by oxidative polycondensation of corresponding 2,5-dialkoxy-1,4-diethynylbenzenes with Hay catalyst. The polymers are soluble in hot solvents such as CHCl₃ and fusible upon heating. UV–Vis spectra of the polymers show an absorption maximum (λ_max) around 420 nm due to the π-conjugation along the main chain. An intense fluorescence exhibiting the λ_max around 475 nm is observed in all of the polymers. Cyclic voltammetry of the polymer shows two Li ion-participated redox reactions occurred at the dialkoxyphenylene moiety and in the conjugated polymer chain due to an n-doping process. Electrical conductivity is an order of 10⁻⁸ S cm⁻¹ which increases to an order of 10⁻⁴ S cm⁻¹ upon vapor phase doping by H₂SO₄. Thermochemical investigations by DSC and polarized optical microscopy suggest that the polymers have a nematic liquid crystalline phase. The molecular arrangements in the phase is evaluated by XRD and a molecular dynamics simulation. A nematic phase is shown to arise from a side-by-side accretion of the rigid rodlike main chains. A lamellar structure is suggested in the crystalline phase.     

Polyterthiophene appended by transition-metal cluster: electropolymerization of 3′-[CCo3(CO)9]-5,2′:5′,2″-terthiophene

Terthiophene, to which cobalt carbonyl cluster complex is π-conjugated, 3′-[CCo₃(CO)₉]-5,2′:5′,2″-terthiophene (3′-CoTTh), was prepared by reaction of 3′-chloromercuro-5,2′:5′,2″-terthiophene with HCCo₃(CO)₉. The molecular structure of 3′-CoTTh is identified by spectroscopic methods and elemental analysis. Cyclic voltammetry of 3′-CoTTh showed deposition of electroactive polymer films on the electrode surface. The absorption spectra of 3′-CoTTh and its polymer films are presented.     

Preparation,crystal structures and electrical conducting properties of new charge-transfer salts: (ET)2·SO3CF3 and (ET)·ClO4

Two new charge-transfer (CT) salts: (ET)₂·SO₃CF₃ and (ET)·ClO₄ were prepared by chemical oxidation of ET with AgSO₃CF₃ and AgClO₄, respectively. Their crystal structures were determined: monoclinic system, Cc, a=35.239(7) Å, b=6.5440(13) Å, c=14.646(3) Å, β=110.26(3)°, V=3168.5(11) Å³ for (ET)₂·SO₃CF₃; monoclinic system, C2/c, a=15.981(3) Å, b=10.627(2) Å, c=11.495(2) Å, β=120.61(3)°, V=1680.2(6) Å³ for (ET)·ClO₄. Electrical conductivity measurements indicate that (ET)₂·SO₃CF₃ shows semi-conducting behaviour with room temperature conductivity of 0.29 S cm⁻¹, while (ET)·ClO₄ is an insulator.     

Photovoltaic properties of a single layer poly [3-(4-octylphenyl)-2,2′-bithiophene] (PTOPT)

A Schottky contact is made from a single layer polymer poly [3-(4-octylphenyl)-2,2′-bithiophene] (PTOPT) in its neutral state and a low work function metal (Al). The electrical and optical properties have been investigated by means of I–V measurements in the dark and under illumination. Various parameters such as the reverse saturation current density, barrier height, and diode quality factor were determined from the I–V curves in the dark of Al/PTOPT/ITO sandwich structure using thermionic emission theory. Spectral response of the device was measured at various wavelengths giving a peak at 500 nm. The IPCE% was obtained for illumination through both the Al and ITO sides. By illuminating the diode with a monochromatic light of wavelength 500 nm, the open-circuit voltage, short-circuit current density, power conversion efficiency, and fill-factor (FF) were obtained. The dependence of photocurrent on light intensity was also recorded and analyzed.     

Crystal Structures of Dy_2(WO_4)_3 and GdY(WO_4)_3

Two compounds, Dy2(WO4)3 and GdY(WO4)3, were synthesized by using the standard solid state reaction technique. The crystal structure was determined by powder X-ray diffraction and Rietveld refinement method. It is found that both compounds have Eu2(WO4)3-type monoclinic structure, with space group C 2/c, Z = 4. The unit cell parameters of Dy2(WO4)3 are a = 0.75981(1) nm. b = 1.13220( 1) nm, c = 1.13254( 1) nm, and β= 109.8001(3)°, and those of GdY(WO4)3 are a = 0.76175(1) nm, b = 1.13543(1) nm, c = 1.13496(2) nm, and bbbbbbbbbβwhile each rare-earth atom is surrounded by eight oxygen atoms. WO4 tetrahedra share their four vertices with REO8 (RE = Dy, Gd, or Y) trigondodecahedra and some REO8 trigondodecahedra share an edge with each other. The phase transition and the magnetic properties were investigated by differential thermal analysis (DTA) and dc superconducting quantum interference device (SQUID) magnetometer.     

A new highly-conjugated TTF analogue: Synthesis,electrochemistry and a conducting TCNQ complex of 9,10-anthracenediylidene-2,2′-bis(4,5-dimethyl-1,3-dithiole)

The TTF analogue (4) has been isolated as the neutral and the dication species. Cyclic voltammetry of (4) reveals a single, two-electron redox couple. Compound (4) is a promising new electron donor and a complex formed with TCNQ is conducting, σ_rt = 10⁻² S cm⁻¹.     

Oxidation ofγ′-Ni3Al andγ′-Ni3Al(Si) intermetallic compounds at low-oxygen pressures

The oxidation behavior of -Ni₃Al and -Ni₃Al(Si) (Ni₇₅Al₂₀Si₅) intermetallic compounds was studied at 1073 K and oxygen partial pressures of 59×10^–6 atm, 1.2×10^–14 atm, and 1.2×10^–19 atm by means of a manometric apparatus, and Rhines packs of NiO/Ni and FeO/Fe, respectively. Oxidation kinetics were determined either by recording weight gains or by measuring the internal-oxidation-zone depths. The structures and morphologies of oxides were also studied. Relatively low oxidation rates occurred for both compounds when oxidized in the manometric apparatus, while fast internal oxidation was observed for both compounds in the NiO/Ni pack. The fastest oxidation occurred in the -Ni₃Al compound in the FeO/Fe pack. A healing Al₂O₃ layer was formed on the surface of -Ni₃Al(Si) compound in the FeO/Fe pack, indicating a synergistic effect between the solute elements in the compound at the oxygen pressures corresponding to the dissociation of FeO. The oxidation rate was found to depend on the volume expansion associated with solute-atom oxidation.     

Nonlinear optical properties of 4-nitroaniline mercuric derivatives and 4-amino-4′-nitrodiphenyl sulfide (ANDS) analogues

We have synthesized several mercuric derivatives of 4-nitroaniline and chalcogen analogues of 4-amino-4′-nitrodiphenyl sulfide (ANDS) and examined their nonlinear optical properties. The second harmonic generation (SHG) intensities, UV-VIS cutoff data, and ß values were determined. Mercuric derivatives 6 and 7 exhibited SHG intensities of 21 and 22; comparable to 2-methyl-4-nitroaniline (MNA, SHG=19) and ANDS (SHG=20).     

Paraffin wax as a diluent for extraction and separation of trivalent gallium, indium, and thallium with 2,6-bis-(1′-phenyl-3′-methyl-5′- oxopyrazole-4′) pyridineacyl

A method is proposed for the extraction and separation of trivalent gallium, indium and thallium from their corre-sponding aqueous solutions at 65°C with 2, 6-bis-(l'-phenyl-3'-methyl-5'-oxopyrazole-4') pyridineacyl (H2PMBPPor H2A)using molten paraffin wax as a diluent. The values of pH 1/2 for extraction of gallium, indium and thallium are 2.62, 4.32 and4.93, respectively. Gallium can be extracted by H2PMBPP at a lower acid medium. The effect of solvent and the composi-tion of the extracted species are reported. And the thermodynamic data of the extraction are also obtained.     

Synthesis, characterization, and biological activities of Pt（Ⅱ） and Pd（Ⅱ）complexes with 2′,3′,4′,5,7-pentahydroxy flavone

Pt(Ⅱ) and Pd(Ⅱ) complexes with 2′,3′,4′,5.7-pentahydroxy-flavone were synthesized and characterized by ele-mental analysis, molar conductance, IR, ′HNMR, TG-DTA, UV-Vis spectroscopic techniques, and fluorescence analysis.The scavenging effect on the superoxide radical (O2) and the inhibitory effect on lipid peroxides were also investigated. Both the ligand and the complexes exhibit scavenging effect on superoxide radicals, and the effect of the complexes is greater than that of the ligand. The Pt(Ⅱ) complex exhibits the strongest scavenging efficiency. Both Pt(Ⅱ) and Pd(Ⅱ) com-plexes have the inhibitory effect on lipid peroxides, and the effect of the complexes is greater than that of the ligand, but the Pt(Ⅱ) complex has a high effect of promoting lipid peroxides.     

Chemical interactions at polymer interfaces: poly(p-xylylene-α-tetrahydrothiophene-bromide,chloride) on indium–tin-oxide

Chemical interactions, at the interface between a precursor polymer for poly(p-phenylenevinylene), namely poly(p-xylylene-α-tetrahydrothiophene-chloride), and an indium–tin-oxide transparent electrode, are identified using X-ray photoelectron spectroscopy. The HCl eliminated in the conversion process interacts with the surface of the indium–tin-oxide substrate leading to the formation of indium chloride which then diffuses into the polymer. It appears that indium–tin-oxide, or possibly the indium chloride generated at the interface, acts as a catalyst for the thermal elimination reaction. The results show unequivocally that interfacial interactions are of major importance in understanding, and ultimately improving, the performance of polymer-based electro-luminescent devices.     

Ce3+掺杂对GdAl3(BO3)4:Dy3+和GdAl3(BO3)4:Tb3+荧光粉发光性能的影响

用湿化学方法合成了Ce3 /Dy3 及Ce3 /Tb3 共掺GdAl3(BO3)4发光材料.利用X射线衍射仪对其进行了物相分析,结果表明:合成物为纯的六方相GdAl3(BO3)4微晶.利用荧光分光光谱仪进行光谱分析,测定了合成样品的激发和发射光谱.发现在紫外激发下,GdAl3(BO3)4:Dy荧光粉发射出很强的偏黄的白光,其发射峰分别位于480,575和665 nm,对应于Dy3 的4F9/2→6H15/2,13/2,11/2跃迁.掺Ce3 对Dy3 起到敏化作用,GdAl3(BO3)4:Dy,Ce发出很亮的暖白光,且强度是GdAl3(BO3)4:Dy的3倍左右.同时,在Ce3 /Tb3 共掺的样品中,由于Ce3 与Tb3 间的能量传递,Tb3 的541 nm特征峰显著增强.     

Long-range magnetic order displayed by a bimetallic pentanuclear cluster complex [(Ni(2,2′-bipy)2)3(Fe(CN)6)2]·13H2O and by a Cu(II) analog

A bimetallic pentanuclear cluster complex contains three bis(2,2′-bipyridine)nickel(II) moieties bridged, through two vacant cis-positions around each nickel, to two separate hexacyanoferrate(III) groups via NiNCFe linkages. Freshly prepared crystals of this compound contain 17 water and two dimethylformamide molecules of solvation per cluster. Loss of some solvent molecules is rapid in air, the resulting ‘partly desolvated’ material showing intracluster ferromagnetic coupling and a S=4 ground state, but without long-range magnetic order. In contrast, a rapidly precipitated powder sample, containing 13 waters of hydration [(Ni(2,2′-bipy)₂)₃(Fe(CN)₆)₂]·13H₂O, displays long-range order at a T_C of 11 K. Inter-cluster interactions occur via the H-bonded water pathways which join neighbouring Fe(CN)₆³⁻ groups in separate clusters. Thus, a new example of inter-cluster magnetic ordering has been achieved. A copper(II)-bipy analog also shows long-range order, with T_C of 13 K. In the absence of a crystal structure, the magnetic and spectral properties of this Cu derivative point to a different structural topology being present.     

Influence of water and electrolyte included in the polymer on the rectifying properties of the junction n-doped silicon/poly(4,4′-dipentoxy-2,2′-bithiophene)

Small amounts of water and electrolyte included in the polymer during the electrochemical polymerization, and detected by thermogravimetric analysis and X-ray diffraction strongly affect the current-voltage characteristics of the system n-doped silicon/poly(4,4′-dipentoxy-2,2′-bithiophene). Current-voltage curves and impedance measurements demonstrated that a double layer is established at the interface relative to the electric contact on the polymer where, probably, the oxidation of water takes place when the rectifying junction is forward biased. These processes affect the transport properties of the junction in different ways, depending on the nature of the contact. It was also found that the properties of the silicon/polymer interface do not depend meaningfully on eventual amounts of water and electrolyte included in the polymer.     

Electrical conductivities and crystal and band-electronic structures of a new phase of BEDT—TTF—bromide salt, (BEDT—TTF)2Br(H2O)3

A new bromide salt of BEDT-TTF, (BEDT-TTF)₂Br(H₂O)₃, was obtained by an electrochemical crystallization of the tetrahydrofuran (THF) solution containing BEDT-TTF, malonic acid, and aqueous tetrabutylammonium hydroxide. Commercially available aqueous Bu₄NOH contaminates Br⁻, which is the anion source of this salt. The temperature dependence of the electrical resistance showed a complex behavior, but the resistance decrease in the low temperature range suggests a metallic ground state down to 4.2 K. Its crystal structure belongs to the δ-type, the example of which was found for δ-(BEDT-TTF)₂AuBr₂. A tight-binding band structure calculation revealed a closed Fermi surface, characteristic of a two-dimensional band structure.