High-intensity light — for instance that from a laser — can be destructive, not only to the human eye, but also to equipment such as imaging sensors and optical communication devices. Therefore, effective protection against such light is desirable. A protection device should ideally have high transmission to non-damaging light, and should also be fast-acting in order to effectively stop high-intensity light. In working towards a protection device, there is a need to conduct fundamental research in order to understand the processes involved. One of the photophysical processes of special interest in the field of optical power limiting (OPL) is reverse saturable absorption, where a compound in an excited state absorbs light more strongly than it does in its ground state. In this work, several novel organoplatinum compounds for OPL, rationally designed to have a strong reverse saturable absorption, have been synthesized. The compounds have been analyzed using linear and nonlinear absorption spectroscopy, luminescence spectroscopy, and quantum chemistry calculations to gain further knowledge regarding their photophysical properties. In addition to this fundamental research, the absorption capabilities of some of these compounds indicate that they can be used for OPL applications. Consequently, compounds from these studies have been incorporated into a sol–gel glass that could be used in optical systems. / <p>Finansiellt stöd från Kempestiftelsen.</p>

京都大学 / 新制・課程博士 / 博士(工学) / 甲第23229号 / 工博第4873号 / 新制||工||1760(附属図書館) / 京都大学大学院工学研究科合成・生物化学専攻 / (主査)教授 松田 建児, 教授 杉野目 道紀, 教授 生越 友樹 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

A quimiluminescência derivada da decomposição induzida de 1,2-dioxetanos e do sistema peróxi-oxalato pode ser explicada através do mecanismo de luminescência iniciada por troca de elétron - CIEEL (\"Chemically Initiated Electron Exchange Luminescence\"). Esta proposta supõe uma transferência de elétron seguida de uma retrotransferência, que pode ocorrer de forma intra ou intermolecular, dependendo do sistema. A etapa de quimiexcitação do sistema peróxi-oxalato envolve uma retro-transferência de elétron intermolecular, da qual participam dois radicais-íons - um deles postulado como o dióxido de carbono radical-anion. Por outro lado, não existe consenso a respeito da via de retro-transferência de elétron na decomposição induzida de 1,2-dioxetanos, que pode ocorrer de forma intra ou intermolecular. Neste trabalho são apresentadas as sínteses de sete 1,2-dioxetanos, os resultados obtidos na investigação da via de quimiexcitação proposta no mecanismo CIEEL para a decomposição induzida de 1,2-dioxetanos e para o sistema peróxi-oxalato e a aplicação da quimiluminescência do luminol em matriz polimérica de poli(vinilpirrolidona) para a calibração de luminômetros de microplacas. Verificou-se, através do estudo do efeito da viscosidade do solvente sobre os rendimentos quânticos singlete na decomposição induzida de 1,2-dioxetanos, uma dependência entre a eficiência de quimiexcitação e o efeito da cavidade de solvente, que foi racionalizada em termos de um modelo difusional e friccional. Estes resultados, associados a cálculos teóricos, tomaram possível postular um mecanismo intramolecular modificado para a decomposição induzida de 1,2-dioxetanos. No sistema peróxi-oxalato foi realizada uma tentativa de detecção direta do dióxido de carbono ânion-radical através de medidas do sinal de ressonância paramagnética de elétron do aduto formado entre &#945;-fenil-N-tert-butilnitrona (PBN), um spin trap, e o radical-anion. Apesar da leve discrepância entre as constantes de acoplamento do sinal observado em relação aos valores relatados na literatura para o aduto PBN-CO2, a caracterização foi realizada preliminarmente através de espectroscopia de massas com injeção direta. Finalmente, foi desenvolvido um sistema para calibração de luminômetros de microplacas, baseado na quimiluminescência de luminol em matriz polimérica, que pode ser utilizado - adicionalmente - na quantificação de peróxido de hidrogênio, em concentrações &#181;mol-1, e agentes redutores com potencial anti-radicalar e antioxidante. / The chemiluminescence resulting from induced decomposition of 1,2-dioxetanes and the peroxyoxalate system can be explained by the Chemically Initiated Electron Exchange Luminescence - CIEEL mechanism. This hypothesis postulates an electron transfer followed by a bond cleavage or rearrangement and back electron transfer which can occur in a intra or intermolecular way, depending on the system. The chemiexcitation step in the peroxyoxalate system involves an intermolecular back electron transfer, in which two radical ions participates - one of them is assumed to be carbon dioxide radical anion. However, there is no consensus about the back electron transfer path in the induced decomposition of 1,2-dioxetanes, which Can occur in an intra or intermolecular way. This work reports the synthesis of seven 1,2-dioxetane derivatives, the results obtained in the investigation of the chemiexcitation path proposed by the CIEEL mechanism for the induced decomposition of 1,2-dioxetanes and for the peroxyoxalate system, and the application of poly(vinylpirrolidone) supported luminol chemiluminescence in the development of a rnicroplate luminometer calibration method. It was possible to confirm, by the study of solvent viscosity effect on singlet quantum yields in induced 1,2-dioxetane decomposition, a dependence between chemiexcitation efficiency and the solvent cavity effect, which was rationalized based on a diffusional and frictional model. These results, together with theoretical calculations, allow us to postulate a modified intermolecular chemiexcitation mechanism for the induced decomposition of 1,2-dioxetanes. An attempt to detect directly the carbon di oxide radical anion in the peroxyoxalate system was made based on the electron paramagnetic resonance detection of the &#945;-phenyl-N-tert-butylnitrone (PBN)-CO2 adduct. Despite small discrepancies between the observed and the previously reported hyperfine coupling constant values, the adduct characterization was confirmed by direct injection mass spectrometry. Finally, a microplate luminometer light intensity calibration system, based on polymeric matrix-supported luminal, was developed. This method can be used also to determine hydrogen peroxide at &#181; mol-1 concentration and to quantify reducing agents with antiradical and antioxidant potential.

A quimiluminescência derivada da decomposição induzida de 1,2-dioxetanos e do sistema peróxi-oxalato pode ser explicada através do mecanismo de luminescência iniciada por troca de elétron - CIEEL (\"Chemically Initiated Electron Exchange Luminescence\"). Esta proposta supõe uma transferência de elétron seguida de uma retrotransferência, que pode ocorrer de forma intra ou intermolecular, dependendo do sistema. A etapa de quimiexcitação do sistema peróxi-oxalato envolve uma retro-transferência de elétron intermolecular, da qual participam dois radicais-íons - um deles postulado como o dióxido de carbono radical-anion. Por outro lado, não existe consenso a respeito da via de retro-transferência de elétron na decomposição induzida de 1,2-dioxetanos, que pode ocorrer de forma intra ou intermolecular. Neste trabalho são apresentadas as sínteses de sete 1,2-dioxetanos, os resultados obtidos na investigação da via de quimiexcitação proposta no mecanismo CIEEL para a decomposição induzida de 1,2-dioxetanos e para o sistema peróxi-oxalato e a aplicação da quimiluminescência do luminol em matriz polimérica de poli(vinilpirrolidona) para a calibração de luminômetros de microplacas. Verificou-se, através do estudo do efeito da viscosidade do solvente sobre os rendimentos quânticos singlete na decomposição induzida de 1,2-dioxetanos, uma dependência entre a eficiência de quimiexcitação e o efeito da cavidade de solvente, que foi racionalizada em termos de um modelo difusional e friccional. Estes resultados, associados a cálculos teóricos, tomaram possível postular um mecanismo intramolecular modificado para a decomposição induzida de 1,2-dioxetanos. No sistema peróxi-oxalato foi realizada uma tentativa de detecção direta do dióxido de carbono ânion-radical através de medidas do sinal de ressonância paramagnética de elétron do aduto formado entre &#945;-fenil-N-tert-butilnitrona (PBN), um spin trap, e o radical-anion. Apesar da leve discrepância entre as constantes de acoplamento do sinal observado em relação aos valores relatados na literatura para o aduto PBN-CO2, a caracterização foi realizada preliminarmente através de espectroscopia de massas com injeção direta. Finalmente, foi desenvolvido um sistema para calibração de luminômetros de microplacas, baseado na quimiluminescência de luminol em matriz polimérica, que pode ser utilizado - adicionalmente - na quantificação de peróxido de hidrogênio, em concentrações &#181;mol-1, e agentes redutores com potencial anti-radicalar e antioxidante. / The chemiluminescence resulting from induced decomposition of 1,2-dioxetanes and the peroxyoxalate system can be explained by the Chemically Initiated Electron Exchange Luminescence - CIEEL mechanism. This hypothesis postulates an electron transfer followed by a bond cleavage or rearrangement and back electron transfer which can occur in a intra or intermolecular way, depending on the system. The chemiexcitation step in the peroxyoxalate system involves an intermolecular back electron transfer, in which two radical ions participates - one of them is assumed to be carbon dioxide radical anion. However, there is no consensus about the back electron transfer path in the induced decomposition of 1,2-dioxetanes, which Can occur in an intra or intermolecular way. This work reports the synthesis of seven 1,2-dioxetane derivatives, the results obtained in the investigation of the chemiexcitation path proposed by the CIEEL mechanism for the induced decomposition of 1,2-dioxetanes and for the peroxyoxalate system, and the application of poly(vinylpirrolidone) supported luminol chemiluminescence in the development of a rnicroplate luminometer calibration method. It was possible to confirm, by the study of solvent viscosity effect on singlet quantum yields in induced 1,2-dioxetane decomposition, a dependence between chemiexcitation efficiency and the solvent cavity effect, which was rationalized based on a diffusional and frictional model. These results, together with theoretical calculations, allow us to postulate a modified intermolecular chemiexcitation mechanism for the induced decomposition of 1,2-dioxetanes. An attempt to detect directly the carbon di oxide radical anion in the peroxyoxalate system was made based on the electron paramagnetic resonance detection of the &#945;-phenyl-N-tert-butylnitrone (PBN)-CO2 adduct. Despite small discrepancies between the observed and the previously reported hyperfine coupling constant values, the adduct characterization was confirmed by direct injection mass spectrometry. Finally, a microplate luminometer light intensity calibration system, based on polymeric matrix-supported luminal, was developed. This method can be used also to determine hydrogen peroxide at &#181; mol-1 concentration and to quantify reducing agents with antiradical and antioxidant potential.

Polycyclic Aromatic Hydrocarbons (PAHs) are harmful by-products formed during combustion of hydrocarbons under locally fuel-rich conditions followed by incomplete combustion. PAHs act as precursors during the formation of soot. PAHs and soot are harmful for human health and legislation limits the emission of unburned hydrocarbons and soot. Consequently, other measures are necessary in order to limit the production of PAHs and soot in internal combustion engines applications, entailing a possible decrease of fuel efficiency and higher technical requirements for automotive manufactures. The combustion chemistry of PAHs is not fully understood, which prompts the need of further investigations. The chemical dynamics shown by novel pathways of PAH formation involving vinylacetylene addition to the phenyl radical opens up new horizons for the potential contribution to PAH formation through this class of reactions. In the present work novel pathways of the formation of naphthalene and phenanthrene are investigated for a laminar premixed benzene flame and a laminar ethylene diffusion flame. The purpose is to improve the prediction of the aromatic species concentration in the flames. A pathway chosen due the high potential aromatic yield is assessed through preliminary flame calculations relying on simplifying assumptions concerning reaction rates. Certain isomerisation steps of the pathway occur within a time-scale characteristic of thermal relaxation processes. Therefore, the solution of the energy grained master equation is necessary in order to calculate the phenomenological reaction rates resulting from a non-equilibrium kinetic modeling. Quantum chemical calculations are performed in order to calculate molecular properties of the species involved. These properties are subsequently processed to determine the rate constants of the sequence of multi-energy well reactions. Moreover, the chemical dynamics of the pathway is analyzed and the effect of temperature and pressure on the kinetic parameters is investigated. Despite of the potential yield demonstrated through the preliminary flame calculations, the computed rate constants show that the studied reactions are insignificant for the formation of naphthalene and phenanthrene in the studied flames. An effort is put on evaluating if the non-equilibrium kinetic modeling adopted for the calculation of the kinetic parameters is consistent with the kinetic modeling used in the flame calculations. The current work provides an efficient method to compute rate constants of multi-energy well reactions at different thermodynamic conditions, characteristic of flames and of combustion in commercial devices or in internal combustion engines. Pathways with a slightly different chemical dynamics should be tested applying the current methodology. Moreover, further studies should be aimed at overcoming possible limits of the kinetic modeling of multi-energy well reactions occurring in combustion environments.

Thin-film organic field effect transistors (OFETs) have attracted growing interest in recent years due to their promising electrical, optical and mechanical properties. Especially, oligothiophenes and their derivates are candidates with good prospects for application as the organic semiconducting material in such devices. They possess an extended, polarisable aromatic π-electron system that promotes a high structural arrangement of the molecules. The charge transport in the organic film is realised in the direction perpendicular to the plane of the thiophene rings via a hopping transport mechanism. Thus, a good π-π-overlap and a consequent stacking of the thiophene molecules in the film perpendicular to the gate substrate is essential to achieve excellent electric properties such as high charge carrier mobilities and low resistive losses. The highly polarisable thiophene-based molecules are also very attractive materials that are potentially applicable as the field-sensitive organic semiconducting component of a ferroelectric OFET device. In such a device, the dielectric gate element of a conventional OFET setup is substituted by a ferroelectric substrate. The electric field that is induced by the polarisation of the ferroelectric material serves as gate field and controlls the charge injection and charge density inside the device. In this thesis, thiophene-based molecules are investigated in detail with respect to their application as field-sensitive organic semiconducting component in a ferroelectric OFET device employing quantum-chemical ab initio and DFT-based methods. We demonstrate that the phosphonic acids can bind the organic molecules to the dielectric or ferroelectric material and well-anchored, robust self-assembled monolayers are formed. Furthermore, special focus is put on the influence of the intermolecular interactions among the organic molecules on the technologically relevant structural and electronic properties. It is found that the CN···HC hydrogen bond link the molecules into extended ribbons, but the π-π-stacking-stacking interaction is the main driving force in the self-assembly of the molecules. We also establish in detail the influence of the electric field on the phosphonic acid anchoring molecule and some quarterthiophene derivates. For the latter, the strongest field-sensitivity is obtained for an external electric field aligned parallel to the extension of the thiophene framework. Hence, they are suitable to act as the field-sensitive organic components in devices that take advantage of a band-gap engineering. Moreover, the present results emphasise the importance of the adsorption morphology of the molecules in the film in a π-stacked fashion with their longitudinal axis oriented parallel to the (orthonormal) electric field induced by the ferroelectric substrate.

Thin-film organic field effect transistors (OFETs) have attracted growing interest in recent years due to their promising electrical, optical and mechanical properties. Especially, oligothiophenes and their derivates are candidates with good prospects for application as the organic semiconducting material in such devices. They possess an extended, polarisable aromatic π-electron system that promotes a high structural arrangement of the molecules. The charge transport in the organic film is realised in the direction perpendicular to the plane of the thiophene rings via a hopping transport mechanism. Thus, a good π-π-overlap and a consequent stacking of the thiophene molecules in the film perpendicular to the gate substrate is essential to achieve excellent electric properties such as high charge carrier mobilities and low resistive losses. The highly polarisable thiophene-based molecules are also very attractive materials that are potentially applicable as the field-sensitive organic semiconducting component of a ferroelectric OFET device. In such a device, the dielectric gate element of a conventional OFET setup is substituted by a ferroelectric substrate. The electric field that is induced by the polarisation of the ferroelectric material serves as gate field and controlls the charge injection and charge density inside the device. In this thesis, thiophene-based molecules are investigated in detail with respect to their application as field-sensitive organic semiconducting component in a ferroelectric OFET device employing quantum-chemical ab initio and DFT-based methods. We demonstrate that the phosphonic acids can bind the organic molecules to the dielectric or ferroelectric material and well-anchored, robust self-assembled monolayers are formed. Furthermore, special focus is put on the influence of the intermolecular interactions among the organic molecules on the technologically relevant structural and electronic properties. It is found that the CN···HC hydrogen bond link the molecules into extended ribbons, but the π-π-stacking-stacking interaction is the main driving force in the self-assembly of the molecules. We also establish in detail the influence of the electric field on the phosphonic acid anchoring molecule and some quarterthiophene derivates. For the latter, the strongest field-sensitivity is obtained for an external electric field aligned parallel to the extension of the thiophene framework. Hence, they are suitable to act as the field-sensitive organic components in devices that take advantage of a band-gap engineering. Moreover, the present results emphasise the importance of the adsorption morphology of the molecules in the film in a π-stacked fashion with their longitudinal axis oriented parallel to the (orthonormal) electric field induced by the ferroelectric substrate.