Synthesis, characterization and electrical conductivity of poly [ethyl trifluorobuty-2-noate]

Poly[ethyl trifluorobuty-2-noate] (PETFB) was prepared from ethyltrifluorobuty-2-noate by anionic polymerization.The polymer was examined by UV-Vis,IR and NMR spec-trometries.It possessed π-conjugated backbone in the main chain.No significant variation in the electrical conductivity of BF3-doped PETFB was observed after more than three months' storage,indicating improved conductive stability in air as compared with polyacetylene.     

Synthesis,characterization, and solid state electrical conductivity of coordination polymers with copper and zinc

Heterobimetallic complexes [Cu _x Zn_{1? x} (dadb)?·?yH₂O] _n {where dadb?=?2,5-diamino-3,6-dichloro-1,4-benzoquinone (1); x?=?1 (2), 0.5 (4), 0.25 (5), 0.125 (6), 0.0625 (7), and 0 (3); y?=?2; n?=?degree of polymerization} were synthesized and characterized. All metal complexes are stable at room temperature but weakly absorb moisture on exposure to air. Monometallic 2 exhibits subnormal magnetic moment whereas 3 exhibits diamagnetism. Heterobimetallic complexes exhibit normal magnetic moments. Heterobimetallic complexes are characterized from powder X-ray diffraction, thermal analysis, and electron spin resonance (ESR) spectral studies. Delocalization of unpaired electron from metal to ligand has been inferred from ESR and natural bond orbital (NBO) analysis. Greater delocalization of unpaired electron of Cu(II) on ligand of 4 as compared to that of 2 is reflected from NBO analysis. Heterobimetallic complexes show higher conductivity than monometallic complexes; all the complexes exhibit semiconductor behavior.     

Preparation,characterization and electrical conductivity of new heterobimetallic chalcogenates and their 1,10-phenanthroline adducts

New mixed metal chalcogenate coordination polymers, MPb(SCN)₂(SeCN)₂ [M = Co^II, Ni^II or Hg^II], Ag₂-Pb(SCN)₂(SeCN)₂, and the complex heterobimetallic salts, [M(phen)₃][Pb(SCN)₂(SeCN)₂][M = Co^II or Ni^II; phen = 1,10-phenanthroline] that have been prepared and characterized by elemental analyses, i.r. and u.v.–vis. spectra, and by powder XRD patterns. Their solid state electrical conductivities have been investigated, show _rt in the 10^–10–10^–6 S cm^–1 range, and semiconduct at 313–383 K with band gaps in the 0.28–0.91 eV range. [Co(phen)₃][Pb(SCN)₂(SeCN)₂], exhibits a remarkable increase, i.e. 10⁴ order of magnitude, in conductivity at higher temperature, which reflects a disordered metallic system where charge carriers have difficulty in crossing the non-conducting barrier at low temperature.     

Synthesis,characterization, electrical conductivity,and catalytic studies of some coordination polymers of salen-type schiff base

Coordination polymers of Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II) with the salen-type Schiff base 4,4′-bis[(N-ethanesalicylaldehydediamine-5)azo]biphenyl have been prepared and characterized by elemental analyses, IR and electronic spectra, magnetic susceptibility measurements, and thermogravimetric analysis. Thermogravimetric analysis confirms the coordination of H₂O in complexes. The ¹H NMR spectrum of ligand clearly indicates the presence of OH and azomethine groups. The octahedral geometry have been suggested for Mn(II), Fe(II), Co(II), and Ni(II) complexes, and square planar Cu((II), whereas tetrahedral is suggested for Zn(II) and Cd(II) polychelates. Thermal data have been analyzed for kinetic parameters by both Coat-Redfern and Broido methods. Solid-state dc conductivity of ligand and its polychelates was measured in their compressed pellet form over 313–413 K temperature range. Solidstate conductivity lies in the range 4.361 × 10⁻¹¹ to 7.241 × 10⁻¹⁰ Ohm⁻¹ cm⁻¹ indicating their semiconducting behavior. Oxidation of styrene with selected catalysts was tested using H₂O₂ as an oxidant.     

Preparation and characterization of polyaniline with high electrical conductivity

In the present paper, polyaniline (PANI) was polymerized by ammonium persulphate using a chemically oxidative process under mild tempertures ranging from ?5–20°C. Electrical conductivity of as synthesized PANI got enhanced gradually owing to the increase in molecular weight and crystallinity with decrease in synthesis temperature. Extraction with tetrahydrofuran (THF) was employed as the purification method of emeraldine base (EB) to enhance the electrical conductivity of PANI effectively attributed to the removal of the low molecular weight fractions and defective molecular chains. Methanesulfonic acid (MSA) was used to dope EB due to its strong acidity and small molecular size, and the amount of dopant versus EB was also optimized. Using a novel “synergistic doping” process with m‐cresol, electrical conductivity of PANI is further enhanced owing to more regular molecular chains which resulted in better interchain charge carriers' conduction. The emeraldine salts obtained finally have high electrical conductivity reaching up to 32.5 S cm^?1, which is much higher than that of the conventionally synthesized sample reported previously. Copyright © 2008 John Wiley & Sons, Ltd.     

Phenyl thiazyl compounds: Synthesis and electrical conductivity

A series of substituted phenylene-dithio-bis(phenyldithiazyl) (PDBPD) and phenylthiophenyldithiazyl (PTPD) compounds have been synthesized utilizing the facile reaction between N-trimethyl silylimides and aromatic sulfenyl chlorides. The compounds are insulators with conductivities of 10^?8–10^?12 (Ω cm)^?1. However, they can be oxidized with Br₂ to conductivities of 10^?3–10^?5 (Ω cm)^?1 for pressed pellets. Electron donating and withdrawing substituents on the phenyl ring markedly alter the electrical transport properties. While PTPD compounds are soluble in many solvents, the PDBPD derivatives are only sparingly soluble.     

Synthesis and characterization of new polyphenols derived from o-dianisidine: The effect of substituent on solubility, thermal stability, and electrical conductivity, optical and electrochemical properties

In this study, we proposed to synthesize soluble polyphenol derivatives containing azomethine bond. For this reason, o-dianisidine was chosen to synthesize Schiff base monomers due to containing dimethoxy groups. Four phenolic Schiff bases were synthesized by condensation reaction of o-dianisidine with salicylaldehyde (2-HBADIAN), 4-hydroxybenzaldehyde (4-HBADIAN), vanillin (MHBADIAN) and 3-ethoxy-4-hydroxybenzaldehyde (EHBADIAN). These monomers were converted to their polyphenol derivatives via oxidative polycondensation reaction (OP). The structures of the obtained compounds were confirmed by FT-IR, UV-vis, ¹H NMR and ¹³C NMR techniques. Progressing of OP was also followed by a time-controlled spectrum mode of a UV-vis spectrophotometer. The molecular weight distribution parameters of the synthesized polyphenols were determined by the size exclusion chromatography (SEC). The synthesized compounds were also characterized by solubility tests, TG-DTA and DSC. Cyclic voltammetry (CV) measurements were carried out and HOMO-LUMO energy levels and electrochemical band gaps () were calculated. Additionally, optical band gaps (E_g) were determined by using UV-vis spectra of the materials. Electrical conductivities of both doped and undoped states of the synthesized materials were measured by four-point probe technique using a Keithley 2400 electrometer showing that P-2-HBADIAN has approximately 130 times higher electrical conductivity than the others. Also, it was stressed that the synthesized polyphenols are semiconductors which have a potential for electronic and optoelectronic applications, with fairly low band gaps.     

Synthesis,identification and study of electrical conductivity of the doped poly aniline

Poly aniline and poly aniline doped with 2,5-dimethyl benzene sulfonic acid (PXSA), 4-hydroxy-m-benzene disulfonic acid (PDSA), 3-chloro-4-hydroxybenzene sulfonic acid (OCPSA) were prepared. The polymers are identified by FT-IR and UV–vis spectroscopy. The ionic conductivities of poly aniline and poly aniline doped with 2,5-dimethyl benzene sulfonic acid (PXSA), 4-hydroxy-m-benzene disulfonic acid (PDSA), 3-chloro-4-hydroxybenzene sulfonic acid (OCPSA) were studied as a function of weight of the dopant compounds. It is noted that an increase of the conductance of poly aniline by doping with OCPSA, and became equal to 0.001321 Ω^?1 for 1 g higher than the conductance for the poly aniline when it is doped with OCPSA.     

Synthesis,characterization, optical,thermal and electrical properties of polybenzimidazoles

The variation of dielectric constant and dielectric loss of two novel polybenzimidazole (PBI) were studied at constant temperature with variable frequency. The polymers have shown maximum dielectric constant at low applied frequency 50 Hz at 393 K due to the space charge polarization. The AC conductivity and activation energy of polymers were arrived from dielectric constant and dielectric loss values. PBIs were synthesized by the oxidative polycondensation of benzimidazole monomers, 2-(1H-benzo [d] imidazole-2-yl)-4-bromophenol (BIBP), and 2-(1H-benzo [d] imidazole-2-yl)-6-methoxyphenol (BIMP) in an aqueous alkaline medium using NaOCl as oxidant. The monomers and polymers were characterized by various spectroscopic techniques. Fluorescence spectra of monomers and polymers showed their λ _max emission in the region of 472–479 and 463–472 nm respectively. The electrical conductivities of iodine doped polybenzimidazoles were measured by four-point probe technique and it increases with increase in iodine vapour contact time. The electrical conductivity values were correlated with the charge density on imidazole nitrogen obtained from Huckel calculation method. Both the PBI are having reasonably good thermal stability and are shown by high carbines residues of around 40% at 500°C in thermogravimetric analysis.     

Synthesis, structure, and conductivity of molecular conductor (PyEt)[Ni(dmit)_2]_2

A new electrical conductive crystal PyEt[Ni(dmit)2]2 (dmit=4,5-dimercapto-1,3-dithiole-2-thione) has been synthesized and its X-ray structure has been determined to be in monoclinic system, C2/c space group. In PyEt[Ni(dmit)2]2 crystal, the conducting component [Ni(dmit)2]0.5- is face-to-face packed forming molecular column along the c-direction, and these molecular columns are then side-by-side extended along the a-direction forming a kind of two-dimensional conducting sheet on (010). The measured conductivity at room temperature along a certain direction on (010) plane is 10 S .cm-1. From 282 to 269 K, the crystal shows metallic behavior but changes to semiconductor below 269 K. Based on the measured crystal structure and calculated band structure, this conductor-semiconductor phase transformation can be primarily interpreted: The metallic conductivity is corresponding to the uniform molecular column and the atomic-lattice-chain structure of Ni chain, while the semi-conductive behavior to staggered mo     

Synthesis and electrical,rheological and thermal characterization of conductive polyurethane

This work studies the electrical, rheological, and thermal characteristics for polyurethane (PU) capped with tetraaniline as a new material, tetraaniline-containing poly(urethane–urea) (TAPU). The conductivities can be increased from less than 10⁻¹⁰ S/cm for pure PU to 10⁻⁴ S/cm for TAPU, independently of the length of the soft segment in the TAPU backbone chain. The tensile strength and modulus are increased when PU is copolymerized with tetraaniline. The viscoelastic creep can be effectively simulated using a Burgers model. Additionally, TAPU has higher viscosity, higher retardation time, and lower compliance J ₁ than regular PU. Restated, TAPU exhibits less elastic but superior permanent deformation than PU because tetraaniline functions as a chain holder. The thermogravimetric analytic (TGA) results reveal that TAPU has lower T _d, smaller T _mw1 and T _mw2, and higher char yield because the dehydration of the urea-containing polymer produces a thin layer from a nitrogen compound on the polymer’s surface, which insulates the underlying polymer from heat and oxygen.     

Synthesis,characterization and enhanced electrical properties of CTAB-directed polyaniline nanoparticles

Inverse microemulsion system of cetyltrimethylammonium bromide (CTAB) molecules is utilized for virtually monodispersed and controlled growth of HCl polyaniline (PANI) nanoparticles at room temperature (ca. 300 K). The templated electroconductive polymer reveals lamellar crystalline structure under X-ray diffraction signifying marked sub-chain alignment of the polymerized nanoparticles. The nanostructured polymer has spherically symmetric morphology in a size range of 2.0 nm to 6.0 nm under electron microscope examination. Gel permeation chromatography gives polydispersity index of 1.02 for nanostructured polymer in agreement with the size monodispersity transpired by electron microscopy. The d.c. electrical conductivity σ _dc of PANI at room temperature is 10.11 S/cm whereas the variation of conductivity with temperature in the range 227–303 K reveals that the conducting mechanism can be considered as three-dimensional variable-range-hopping (3D-VRH). UV-Vis spectrum indicates two broad absorption bands due to polaron formation that contributes to enhanced electrical conductivity of the polymer. The fundamental absorption edge in the polymer is formed by direct allowed transitions to the extent that the optical band gap value was found to be 2.35 eV. The crystalline nanostructure and homogeneous doping attained in the cationic template of amphiphile are argued as contributing factors to the enhanced conductivity of the polymer.     

Synthesis, characterization, and electrical and electrochemical properties of sandwich dilutetium tetraphthalocyanine

Lu2Pc2 and lithium hexylthio-phthalocyanine have been used to synthesize [Lu2(Pc)4] which exhibits variable range hopping conductivity as inorganic semiconductors and also observed electrochromic effect from cyclic voltammetric (CV) measurement.     

Sol-gel synthesis,thermal characterization and conductivity of new glass-polymer solid electrolytes

Poly(ethylene oxide) (PEO) based-polymeric solid electrolytes are of growing interest for their applications in electrochemical devices. Their major limitations are structural and electrochemical stability, and low cationic transport number. A possible response to these problems is given by composite or nanostructured materials. We present sol-gel synthesis, thermal and electrical characterization of new electrolytes made of a composite glass-polymer matrix doped with LiClO₄ and LiBF₄. Emphasis to the critical aspects of preparation is given. We obtain a conductivity at room temperature better than 10^?5 ohm^?1 cm^?1, which is high enough to envisage technological applications.     

Synthesis,characterization, pyrolysis kinetics and conductivity studies of chloro substituted cobalt phthalocyanines

Cobalt(II) phthalocyanine (CoPc), cobalt(II) tetrachloro phthalocyanine (CoPcCl₄), cobalt(II) octachloro phthalocyanine (CoPcCl₈) and cobalt(II) hexadecachloro phthalocyanine (CoPcCl₁₆) are synthesized pure and characterized using elemental analysis, UV-visible, IR-spectroscopy, magnetic susceptibility, X-ray crystallography, and thermogravimetry. All four complexes have monoclinic structure with different crystal lattice constants. Broido's, Coats-Redfern and Horowitz-Metzger relations were employed to calculate the kinetic and activation parameters associated with thermal decomposition of the above complexes. The compounds are analyzed for kinetic parameters, activation energies for decomposition and the Arrhenious pre-exponential factors, in their pyrolysis. Using these factors and standard equations, thermodynamic parameters such as enthalpy, entropy and free energies are calculated. The activation energies are evaluated based on their electrical conductivity conducted over the temperature range 30–200°C. The electrical conductivities observed at 30°C are in the order CoPcCl₁₆?>?CoPcCl₄?>?CoPcCl₈?>?CoPc. The relevant electrical conductivity data are reported.     

Synthesis, characterization, and biological evaluation of new oxime-phosphazenes

Hexachlorocylotriphosphazene (1) was reacted with 4-hydroxy-3-methoxybenzaldehyde to give hexakis[(4-formyl-2-methoxy)phenoxy]cyclotriphosphazene (2). Hexakis[(4-(hydroxyimino)2-methoxy)phenoxy]cyclotriphosphazene (3) was synthesized by reaction of 2 with hydroxlamine hydrochloride in pyridine. Compound 3 was reacted with benzyl chloride, acetyl chloride, allyl bromide, benzoyl chloride, propanoyl chloride, 4-methoxybenzoyl chloride, 2-chlorobenzoyl chloride, chloroacetyl chloride, methyl iodide, and thiophene-2-carbonyl chloride. From these reactions, full or partially substituted compounds were obtained, usually in high yields. Pure or defined products could not be obtained from reaction of 3 with methacryloyl chloride and O-acetylsalicyloyl chloride. The structures of the compounds were determined by elemental analysis, and IR, ¹H, ¹³C, and ³¹P NMR spectroscopy. The synthesized compounds were screened for in-vitro antimicrobial activity against two Gram-positive bacteria (Staphylococcus aureus and Enterococcus faecalis), two gram-negative bacteria (Escherichia coli and Klebsiella pneumonia), and fungal strains (Aspergillus niger, and Candida albicans) by the agar well diffusion method. Few compounds had significant activity against both Gram-positive and Gram-negative bacteria. None of the compounds had antifungal activity except compounds 7 and 9, which had moderate activity.     

Synthesis,characterization and electrochemical properties of new phthalocyanines

The chemical synthesis and characterization with spectroscopic and electrochemical properties of [bis(4-fluorophenyl)-methoxy]-substituted metallo-phthalocyanines were reported for the first time. The new phthalocyanines have been characterized by elemental analysis, UV-Vis, FT-IR, and mass spectroscopies. The aggregation behavior of the phthalocyanine compounds was investigated in different solvents and concentrations. It is found that the fluoro substituents of peripherally Co and Cu complexes are examined and induce a shift to the redox processes toward the negative potentials and formed more reversible processes. Metal-based reduction and oxidation reactions were obtained for the Co(II) complex, whereas Cu(II) complexes exhibited Pc-ring-based electron-transfer reactions. The voltammetric measurements supported the proposed structure of the complexes.     

Synthesis and properties of a new kind of one-dimensional conductor VIII. Synthesis and characterization of trans-bis-1-alkynyl substituted silicon,germanium, tin phthalocyanines and germanium hemiporphyrazines

The preparation of several new trans-bis-1-alkynyl(phthalocyaninato)silicon (VIc—f), -germanium (VIIc—f) and -tin (VIIId, f) compounds as well as trans-bis-1-alkynyl(hemiporphyrazinato)germanium (XIc, e, f) derivatives is described. The products were obtained in high yields by treating the corresponding dichlorides (I, II, IV, X; X = (Cl) with 1-alkynyl Grignard reagents (Vc—f) in tetrahydrofuran (THF) and were characterized spectroscopically. The compounds obtained are considered as models for a new kind of one-dimensional conductor.     

Physicochemical characterization,thermal, and electrical conductivity studies of some transition metal complexes of bis-chelating Schiff base

Polychelates of Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and VO(IV) with a new bis-chelating Schiff base derived from 5-acetyl-2,4-dihydroxyacetophenone and isonicotinic acidhydrazide have been synthesized. The resulting polychelates have been characterized by elemental analyses, IR and electronic spectral data, magnetic susceptibility measurements and thermogravimetric analysis. All the polychelates are dark coloured solids and insoluble in water and common organic solvents. Thermogravimetric analyses confirm coordination of water in complexes. Various kinetic and thermodynamic parameters have been evaluated from thermal data. The ligand acts as a bis-tridentate molecule coordinating through deprotonated phenolic/enolic oxygen atoms and azomethine nitrogen atoms. The solid-state conductivity of ligand and its polychelates have been measured in their compressed pellet form and all compounds were found to be semiconducting in nature.     

Synthesis,characterization, electrical and biological studies on some bivalent metal complexes

Metal complexes of manganese(II), iron(II), cobalt(II), nickel(II), copper(II), zinc(II), and cadmium(II) with Schiff base derived from 2,5-dihydroxyacetophenone and s-benzyldithiocarbazate have been synthesized and characterized by elemental analysis, thermogravimetric analysis, molar conductance, molecular weight, magnetic susceptibility measurements, and electronic and infrared spectra. The molar conductivity data show them to be nonelectrolytes. The Schiff base behaves as a tridentate dibasic ONS donor towards metal ions. Thermal analyses indicate the presence of water in the complexes, making them six and four coordinates. The solid state electrical conductivity of the ligand and its complexes has been measured in the temperature range 313–414 K and the complexes are found to show semiconducting behavior. The antibacterial activities of the ligand and its complexes have also been screened against various organisms and it is observed that the coordination of metal ions has a pronounced effect on the bacterial activity of the ligand.