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Intermediates for Paracyclophane SynthesisLin, Ying-tsung 08 1900 (has links)
It is proposed in this thesis that the imperfect systems of Cram and of Schubert be combined with some modifications.
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Characterization and polymerization of a cyclic precursor to poly(p-phenylene sulfide)Zimmerman, Dean Arthur January 1995 (has links)
No description available.
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Investigations of Photocatalyst TiO2 and Organic Light-emitting MaterialsKuo, Ming-Yu 10 July 2004 (has links)
TiO2. Structural and electronic properties of TiO2 polymorphs denser than rutile, i.e. £\-PbO2-, baddeleyite, fluorite, and cotunnite-type were calculated by a first-principle pseudo-potential method based on density functional theory with local density approximation. Using experimental and theoretical lattice parameters of ambient TiO2, i.e. anatase and rutile as standard, the fluorite-type TiO2 has the narrowest band gap among the post-rutile phases. This character is important for the potential applications as visible-light-responsive photocatalyst.
In additional to the bulk properties of dense TiO2 polymorphs the surface energies of
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Intermolecular Association of an Oblong Shape-persistent Macrocycle and Refunctionalization of Folding ortho-Phenylene OligomersChu, Meng 20 July 2016 (has links)
No description available.
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Linear And Hyperbranched Polybenzyls And Poly(Meta-Phenylenes)Som, Abhijit 01 1900 (has links) (PDF)
No description available.
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Model calculations of the optical absorption of poly(p-phenylene)Paulley, Alan January 1998 (has links)
No description available.
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Eletrossíntese e propriedades ópticas e morfológicas de filmes de poli-p-fenileno e derivados / Electrosynthesis, optical and morphological properties of poly-p-phenylene films and derivativesEiras, Carla 28 June 2004 (has links)
Nesta tese, estudamos a eletrossíntese de polímeros conjugados eletroluminescentes no azul. Filmes de poli(p-fenileno) (PPP), co-poli(p-fenileno-pirrol) (CPPI) e co-poli(p-fenileno-3-metiltiofeno) (CFMET) foram preparados por voltametria cíclica em eletrodos de vidro condutor (ITO) em uma solução não-aquosa de acetonitrila e perclorato de tetrabutilamônio contendo os monômeros e pares de co-monômeros a diferentes concentrações. Durante a síntese dos filmes de PPP, CPPI e CP3MET, a célula eletroquímica foi posicionada dentro de uma caixa seca contendo CaCl2 como agente secante e em atmosfera de N2(g) super-seco com o objetivo de reduzir a umidade do ar no meio de síntese. A baixa umidade do ar obtida durante as medidas permitiu o controle de parâmetros de crescimento dos filmes de PPP e de seus derivados (CPPI e CP3MET). A morfologia dos filmes foi correlacionada aos seus valores de espessura e de rugosidade obtidos por microscopia de força atômica (AFM). As propriedades ópticas dos filmes foram também investigadas por espectroscopia no UV-VSNIR em função do número de ciclos da varredura obtidos durante a eletrossíntese. As respostas eletroquímicas, dos filmes de FPP, CPPI e CP3MET foram obtidas por voltametria cíclica em uma solução livre de monômero. Estes filmes tiveram ainda a confirmação de suas estruturas químicas por meio de resultados obtidos por espectroscopia no infravermelho (FTIR) e por microespectroscopia e mapeamento Raman / This work describes the electrochemical synthesis of poly(p-phenylene) (PPP), p-phenylene-pyrrole copolynier (GPPIC) and p-phenylene-3methylthiophene copolymer (CP3MET). The main interest in studying these materials comes from its blue-electroluminescent properties, which make them suitable for application in electroluminescent devices. The polymerization was carried out using cyclic voltammetry in an acetonitrile non-aqueous medium containing tetrabutylammonium perchlorate and different concentration of each monomer. All the films were synthesized onto indium-tin-oxide covered glass (EO) electrodes. In order to enhance the film quality, electropolymerization was carried out within a glove box containing CaCl2, which was added as a drying agent, and under N2 atmosphere. The low amount humidity during the measurements allowed us to correlate the morphological, electrochemical and optical properties of the films of PPP and derivatives (CPPI and CP3MET). The optical properties of the films were investigated by UV-VIS-NIR spectroscopy after varying the number of cyclos reached during the preparation of the films. The electrochemical response of the films was analyzed via cyclic voltammetry using a monomer-free electrolytic solution. The morphology of the films was correlated to their values of thickness and roughness as obtained by using atomic force microscopy (AFM) and the structural characterization of PPP e their derivatives were obtained by micro-Raman spectroscopy and Raman mapping.
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Synthesis and properties of π-stacked phenylene ethynylene oligomers with a 1,8- substituted naphthalene bridging scaffoldCarson, Bradley Edward 11 May 2010 (has links)
The field of molecular electronics includes the study of conjugated oligomers and
polymers that have significant potential for use in devices such as light emitting diodes
(LEDS), field effect transistors (FETS), and photovoltaic solar cells. These materials may
replace inorganic semiconductors in these devices, Achieving better device performance
through lowering the band-gap and achieving higher field effect mobilities will benefit
from a greater fundamental understanding of charge transfer through the aromatic
subunits. π-stacking of segments of conjugated polymers has been identified as a key
feature that influences the charge transfer through semiconducting organic materials.
Optimizing the molecular architecture of conjugated polymers has the potential to
provide materials with better charge mobility. While devices might benefit from materials
that take advantage of π-stacking, access to π-stacked structures presents a synthetic
challenge. 1,8-Disubstituted naphthalenes may serve as simple covalent bridging
scaffolds which might hold conjugated oligomers in a π-stacked arrangement. The
research described in this thesis focuses on the synthesis of well-defined phenylene
ethynylene oligomers coupled to naphthalene to serve as experimental models of closely
π-stacked aromatic units in conjugated polymers. The π-stacked molecules reported in
this dissertation are characterized by NMR, IR, and mass spectrometry. The effects of π-
stacking on the structure and behavior of conjugated oligomers are determined by X-ray
crystallography, spectroscopy, and electrochemistry.
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Molecular Engineering of Conjugated Polymers for Sensor ApplicationsVetrichelvan, Muthalagu, Valiyaveettil, Suresh 01 1900 (has links)
In recent years, the application of fluorescent conjugated polymers for sensing chemical and biological analytes has received much attention from many researchers. A promising development in this direction was the fabrication of conducting polymer-based sensors for the detection of metal ions, small organic molecules and biomolecules. Herein, we have designed, synthesized and studied a series of copolymers containing alternate phenylene and 2,5- or 2,6-substituted pyridine rings. The basic N-atom of the pyridine ring and the adjacent –OH group from the phenyl ring provide binding sites for metal ions. Another series of water-soluble conjugated polymers with propoxy sulfonate side chains are investigated for biosensor applications. Significant quenching of the polymer fluorescence upon addition of viologen derivatives was also observed. The quenching effect on the polymer fluorescence confirmed that the newly synthesized polymers can be useful in the application of metal and biological sensors. / Singapore-MIT Alliance (SMA)
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Eletrossíntese e propriedades ópticas e morfológicas de filmes de poli-p-fenileno e derivados / Electrosynthesis, optical and morphological properties of poly-p-phenylene films and derivativesCarla Eiras 28 June 2004 (has links)
Nesta tese, estudamos a eletrossíntese de polímeros conjugados eletroluminescentes no azul. Filmes de poli(p-fenileno) (PPP), co-poli(p-fenileno-pirrol) (CPPI) e co-poli(p-fenileno-3-metiltiofeno) (CFMET) foram preparados por voltametria cíclica em eletrodos de vidro condutor (ITO) em uma solução não-aquosa de acetonitrila e perclorato de tetrabutilamônio contendo os monômeros e pares de co-monômeros a diferentes concentrações. Durante a síntese dos filmes de PPP, CPPI e CP3MET, a célula eletroquímica foi posicionada dentro de uma caixa seca contendo CaCl2 como agente secante e em atmosfera de N2(g) super-seco com o objetivo de reduzir a umidade do ar no meio de síntese. A baixa umidade do ar obtida durante as medidas permitiu o controle de parâmetros de crescimento dos filmes de PPP e de seus derivados (CPPI e CP3MET). A morfologia dos filmes foi correlacionada aos seus valores de espessura e de rugosidade obtidos por microscopia de força atômica (AFM). As propriedades ópticas dos filmes foram também investigadas por espectroscopia no UV-VSNIR em função do número de ciclos da varredura obtidos durante a eletrossíntese. As respostas eletroquímicas, dos filmes de FPP, CPPI e CP3MET foram obtidas por voltametria cíclica em uma solução livre de monômero. Estes filmes tiveram ainda a confirmação de suas estruturas químicas por meio de resultados obtidos por espectroscopia no infravermelho (FTIR) e por microespectroscopia e mapeamento Raman / This work describes the electrochemical synthesis of poly(p-phenylene) (PPP), p-phenylene-pyrrole copolynier (GPPIC) and p-phenylene-3methylthiophene copolymer (CP3MET). The main interest in studying these materials comes from its blue-electroluminescent properties, which make them suitable for application in electroluminescent devices. The polymerization was carried out using cyclic voltammetry in an acetonitrile non-aqueous medium containing tetrabutylammonium perchlorate and different concentration of each monomer. All the films were synthesized onto indium-tin-oxide covered glass (EO) electrodes. In order to enhance the film quality, electropolymerization was carried out within a glove box containing CaCl2, which was added as a drying agent, and under N2 atmosphere. The low amount humidity during the measurements allowed us to correlate the morphological, electrochemical and optical properties of the films of PPP and derivatives (CPPI and CP3MET). The optical properties of the films were investigated by UV-VIS-NIR spectroscopy after varying the number of cyclos reached during the preparation of the films. The electrochemical response of the films was analyzed via cyclic voltammetry using a monomer-free electrolytic solution. The morphology of the films was correlated to their values of thickness and roughness as obtained by using atomic force microscopy (AFM) and the structural characterization of PPP e their derivatives were obtained by micro-Raman spectroscopy and Raman mapping.
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