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Your search keyword '"Makarand V. Joshi"' showing total 3 results
Start Over Author "Makarand V. Joshi" Topic electron paramagnetic resonance
3 results on '"Makarand V. Joshi"'

1. New conducting polymers: PF6-doped XYZ-triheterocycles based on X, Y, Z= thiophene, furan and n-methylpyrrole

Author

Allan J. McKinley, Michael P. Cava, Jason L. Cain, Makarand V. Joshi, Robert M. Metzger, and Martin G. Bakker

Subjects
Conductive polymer, Materials science, Mechanical Engineering, Doping, Metals and Alloys, Conductivity, Condensed Matter Physics, Polaron, Electronic, Optical and Magnetic Materials, law.invention, chemistry.chemical_compound, chemistry, Mechanics of Materials, law, Furan, Polymer chemistry, Materials Chemistry, Thiophene, Physical chemistry, Charge carrier, Electron paramagnetic resonance
Abstract

A number of triheterocycles XYZ, where X, Y, Z = furan (O), thiophene (S), or N-methylpyrrole (N) were prepared, and the polymers, obtained by oxidizing them with NOPF6, were studied by four-probe DC conductivity and EPR. SSS has a conductivity of 2.4 S cm−1 at room temperature, and 0.0075 spin/triheterocycle, while SOS has a conductivity of 0.2 S cm−1 and 0.15 spins/triheterocycle; both have narrow Lorentzian EPR lineshapes. The other samples had conductivities below the measurement threshold (10−5 S cm−1). We postulate that NOPF6 overoxidized the polymers, thereby creating more bipolarons than polarons, and reducing the number of charge carriers. more...

Published
1993
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2. ChemInform Abstract: Synthesis, Electrical Conductivity and Electron Paramagnetic Resonance Spectroscopy of Polymers Derived from NOPF6-Doped XYZ-Triheterocycles Based on Pyrrole, Furan and Thiophene

Author

Makarand V. Joshi, Martin G. Bakker, Jason L. Cain, Christine Hemler, Allan J. McKinley, Robert M. Metzger, and Michael P. Cava

Subjects
Radical, Doping, General Medicine, Polaron, Planarity testing, law.invention, chemistry.chemical_compound, Crystallography, chemistry, law, Furan, Thiophene, Electron paramagnetic resonance, Pyrrole
Abstract

A series of triheterocycles; [graphic omitted] for X, Y, Z = OOO, SSS, SOS, SSO, OSO, SOO, O(N-Me)O, S(N-Me)O and S(N-Me)S have been synthesised; of these O(N-Me)O, SOO and S(N-Me)O are new. The triheterocycles were chemically polymerised and oxidised with NOPF6. Only the polymers derived from SSS, SOS and SSO show appreciable conductivities. EPR studies indicate the presence of polarons in SSS, SOS, SSO and, at lower concentrations, in OOO. All the samples appear to show an easily saturable EPR signal assigned to localised radicals. In OSO, SOO, O(N-Me)O, S(N-Me)O and S(N-Me)S this signal displays considerable asymmetry, and g-values significantly above the free electron value. S(N-Me)S shows a higher g-value consistent with a loss of planarity. more...

Published
2010
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3. Synthesis, electrical conductivity and electron paramagnetic resonance spectroscopy of polymers derived from NOPF6-doped XYZ-triheterocycles based on pyrrole, furan and thiophene

Author

Michael P. Cava, Jason L. Cain, Christine Hemler, Robert M. Metzger, Allan J. McKinley, Martin G. Bakker, and Makarand V. Joshi

Subjects
Radical, Doping, Polaron, Planarity testing, law.invention, chemistry.chemical_compound, Crystallography, chemistry, law, Furan, Polymer chemistry, Thiophene, Electron paramagnetic resonance, Pyrrole
Abstract

A series of triheterocycles; [graphic omitted] for X, Y, Z = OOO, SSS, SOS, SSO, OSO, SOO, O(N-Me)O, S(N-Me)O and S(N-Me)S have been synthesised; of these O(N-Me)O, SOO and S(N-Me)O are new. The triheterocycles were chemically polymerised and oxidised with NOPF6. Only the polymers derived from SSS, SOS and SSO show appreciable conductivities. EPR studies indicate the presence of polarons in SSS, SOS, SSO and, at lower concentrations, in OOO. All the samples appear to show an easily saturable EPR signal assigned to localised radicals. In OSO, SOO, O(N-Me)O, S(N-Me)O and S(N-Me)S this signal displays considerable asymmetry, and g-values significantly above the free electron value. S(N-Me)S shows a higher g-value consistent with a loss of planarity. more...