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Excitation wavelength-dependent Raman spectra of single-layer graphene-phtalocyanine hybrid systems
Uhlířová, Tereza ; Vlčková, Blanka (advisor) ; Němec, Ivan (referee)
A systematic chemical and spectroscopic approach to evaluation of the effect of single-layer graphene (SLG) on Raman spectra of free-base phthalocyanine (H2Pc) in glass/SLG/H2Pc hybrid systems has been developed. By a combi- nation of electronic absorption spectra, Raman spectra at five excitation wave- lengths (532, 633, 647, 785 and 830 nm) and excitation profiles of H2Pc Raman spectral bands, the constitution of the three prepared hybrid sysems has been es- tablished in the following manner: Hybrid system I comprises probably a bilayer of H2Pc molecules, system VI approximately a monolayer of H2Pc, and system X a slightly reorganized monolayer of H2Pc molecules. Micro-Raman spectral map- ping of all three hybrid systems yielded H2Pc spectral bands (together with the SLG spectral bands) at all five excitation wavelengths. By contrast, for all three HOPG/H2Pc reference systems (HOPG = highly oriented pyrolytic graphite), prepared by the same procedure as the corresponding samples, H2Pc signal was detected only at 633 and 647 nm excitations. A selective increase of normalized Raman intensities of H2Pc spectral bands for the glass/SLG/H2Pc monolayer hybrid systems at 830 nm was revealed on the basis of a mutual comparison of Raman excitation profiles of all three samples of glass/SLG/H2Pc hybrid systems....
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Time-resolved potentiometry on liquid-liquid interface
Mansfeldová, Věra ; Nesměrák, Karel (advisor) ; Opekar, František (referee) ; Gál, Miroslav (referee)
Věra Mansfeldová: Time-resolved potentiometry on liquid-liquid interface (Dissertation thesis) Abstract The aim of this work is to explore the method of temporal resolution in potentiometry as a new prospective electrochemical analytical technique. In connection with interface of two immiscible electrolyte solutions (ITIES) it may find utilization in analytical chemistry. This technique up to my knowledge has not been published yet. Potential response of analyte on liquid/liquid interface includes both distribution processes, their temporal resolution and redox processes, which specificity can modified by changing the composition of individual phases. Unlike "classic" potentiometric techniques, limited just to potential determination, this method, which I have given the working name "time resolved potentiometry at liquid-liquid interface" utilizes time development of potential response, which was found to be an analyte-specific function. The time resolved potentiometry presented in this work includes time course of potential response to analytical parameters specific for particular analyte. It brings series of data characterizing the analyte in given environment in a similar manner as spectra and may allow creating analyte-specific data package - fingerprint. Combination with ITIES allows, unlike...
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Preparation and photophysical evaluation of tetra-3,4-pyridoporphyrazines suitable for the photodynamic therapy
Čermák, Pavel ; Nováková, Veronika (advisor) ; Roh, Jaroslav (referee)
Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department: Department of Biophysics and Physical Chemistry Candidate: Pavel Cermak Supervisor: Assoc. Prof. Veronika Novakova, PhD. Title of Thesis: Preparation and photophysical evaluation of tetra-3,4- pyridoporphyrazines suitable for the photodynamic therapy Tetra-3,4-pyridoporphyrazines (TPyPz) are aza-analogues of phthalocyanines. Their large system of conjugated bonds enables them to absorb light in the red part of the absorption spectrum. Due to their ability to produce singlet oxygen, they can be potentially used as photosensitizers in photodynamic therapy (PDT). Its mechanism is based on co-functioning of three elements - photosensitizer, light and oxygen. Photosensitizer excited by light absorption transfers its energy into tissue oxygen, thus, creating cytotoxic singlet oxygen. This method is beneficial for its high selectivity, low toxicity, minimal invasion and fast effect. The aim of this work was to synthetize and study water-soluble TPyPz suitable for PDT. Water solubility was achieved by quarternized amines, forming of salts or using suitable delivery systems (hydrophilic emulsion). Hydrophilicity was also increased by introduction of hydrophilic non-charged substituents (OH). At first, appropriate precursors for...
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Synthesis and photophysical study of hydrophilic tetrapyridoporphyrazines bearing charged substituents on the periphery
Demuth, Jiří ; Nováková, Veronika (advisor) ; Vávrová, Kateřina (referee)
Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department Department of Biophysics and Physical Chemistry Candidate Jiří Demuth Supervisor Assoc. Prof. Veronika Nováková, PhD. Title of Thesis Synthesis and photophysical study of hydrophilic tetrapyridoporphyrazines bearing charged substituents on the periphery Phthalocyanines are planar organic molecules, which have a metal cation coordinated in their centre. This work deals with their aza-analogues - tetra-3,4-pyridoporphyrazines (TPyPz). TPyPz can absorb light in red part spectrum and then produce singlet oxygen. Due to this ability, they may be used in photodynamic therapy (PDT) of cancer. PDT's mechanism is based on three components: photosensitizer, light and singlet oxygen. Photosensitizer transfers energy of absorbed light to oxygen making, thus, cytotoxic singlet oxygen. The goal of this thesis was to synthesize water soluble TPyPzs absorbing in red part of absorption spectrum. TPyPzs bearing different charged substituents will be compared within the series. The synthesis consisted of preparation of 2-chloro-5,6-dimethylpyridine-3,4-dicarbonitrile (1), which was the starting precursor for other reactions. Nucleophilic substitution of 1 was used for the introducing of various hydrophilic substituents. Prepared precursors...
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Optimalization of methods for determination of singlet oxygen production and fluorescence emission of azaphthalocyanine derivatives
Hrubá, Lenka ; Nováková, Veronika (advisor) ; Kubíček, Vladimír (referee)
Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department: Department of Biophysics and Physical Chemistry Candidate: Lenka Hrubá Supervisor: Assoc. Prof. Veronika Nováková, Ph.D. Title of Thesis: Optimization of methods for determination of singlet oxygen production and fluorescence emission of azaphthalocyanine derivatives Photodynamic therapy (PDT) with a singlet oxygen as an essential agent is believed to be an alternative way of cancer treatment or treatment of some cutaneous diseases. The principle of PDT is based on excitation of a photosensitizer by light absorption, followed by transfer of energy to tissue oxygen (3 O2) forming cytotoxic singlet oxygen (1 O2). The efficiency by which photosensitizer transforms absorbed energy to singlet oxygen is characterized by singlet oxygen quantum yields (ΦΔ). The aim of this thesis was to develop and optimize absolute method for determination of ΦΔ. In comparison to a relative method, no reference is needed in this case, which enables accurate results with lower error. Verification of the new method was performed in N,N- dimethylformamide with a zinc phthalocyanine as a model photosensitizer because of its well-known ΦΔ and with 1,3-diphenylisobenzofuran as a chemical quencher of 1 O2. Different sources of light for excitation...
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Optimalization of methods for determination of singlet oxygen production and fluorescence emission of azaphthalocyanine derivatives
Hrubá, Lenka ; Nováková, Veronika (advisor) ; Kubíček, Vladimír (referee)
Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department: Department of Biophysics and Physical Chemistry Candidate: Lenka Hrubá Supervisor: Assoc. Prof. Veronika Nováková, Ph.D. Title of Thesis: Optimization of methods for determination of singlet oxygen production and fluorescence emission of azaphthalocyanine derivatives Photodynamic therapy (PDT) with a singlet oxygen as an essential agent is believed to be an alternative way of cancer treatment or treatment of some cutaneous diseases. The principle of PDT is based on excitation of a photosensitizer by light absorption, followed by transfer of energy to tissue oxygen (3 O2) forming cytotoxic singlet oxygen (1 O2). The efficiency by which photosensitizer transforms absorbed energy to singlet oxygen is characterized by singlet oxygen quantum yields (ΦΔ). The aim of this thesis was to develop and optimize absolute method for determination of ΦΔ. In comparison to a relative method, no reference is needed in this case, which enables accurate results with lower error. Verification of the new method was performed in N,N- dimethylformamide with a zinc phthalocyanine as a model photosensitizer because of its well-known ΦΔ and with 1,3-diphenylisobenzofuran as a chemical quencher of 1 O2. Different sources of light for excitation...
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Time-resolved potentiometry on liquid-liquid interface
Mansfeldová, Věra
MSc. Věra Mansfeldová Dissertation thesis: Time-resolved potentiometry on liquid-liquid interface Abstract The aim of this work is to explore the method of temporal resolution in potentiometry as a new prospective electrochemical analytical technique. In connection with interface of two immiscible electrolyte solutions (ITIES) it may find utilization in analytical chemistry. This technique up to my knowledge has not been published yet. Potential response of analyte on liquid/liquid interface includes both distribution processes, their temporal resolution and redox processes, which specificity can modified by changing the composition of individual phases. Unlike "classic" potentiometric techniques, limited just to potential determination, this method, which I have given the working name "time resolved potentiometry at liquid-liquid interface" utilizes time development of potential response, which was found to be an analyte-specific function. The time resolved potentiometry presented in this work includes time course of potential response to analytical parameters specific for particular analyte. It brings series of data characterizing the analyte in given environment in a similar manner as spectra and may allow creating analyte-specific data package - fingerprint. Combination with ITIES allows, unlike...
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Low-molecular materials for organic electronics and photonics
Češka, Matěj ; Salyk, Ota (referee) ; Weiter, Martin (advisor)
This master´s thesis deals with organic materials for use in electronics and photonics. Attention was paid to low molecular weight materials. The theoretical part of this thesis contains brief introduction to organic electronics and photonics. In particular, organic transistors, organic solar cells and organic light-emitting diodes are mentioned. The experimental part is focused on study of electrical and optical properties of two types of phthalocyanines. Thin films and solutions of phthalocyanines were characterized by UV-VIS spectroscopy. Thin films were also characterized by current voltage characteristics, spectral response measurement of photocurrent and by method of transient photoconductivity. It was found that illumination affects the electrical properties of thin layers of phthalocyanines, the performance of the prepared thin films depends on the type phthalocyanine and also depends on the thickness of the layer.
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Study of electrical and dielectric properties of thin polymer films
Miklíková, Zdeňka ; Novák, Vítězslav (referee) ; Zmeškal, Oldřich (advisor)
The thesis is focused on the study of electric and dielectric properties of thin-film organic materials that can be used as an active layer of photovoltaic cells. Primarily were studied the properties of the layers on the glass substrate, which consist of a thin active layer of mixture ZnPc/PCBM with Al or Au contact. On the selected samples were first measured current-voltage characteristics in the dark and during the exposure then on the selected samples were measured frequency dependences (impedance spectra) in the dark and finally on the selected samples were measured relaxation characteristics (transient response analysis – current dependences on time at constant voltage) in the dark. The measured data for transient measurement were evaluated using the methods of fractal analysis in HarFA. The results will be used to optimize the properties of photovoltaic cells.
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Charge carrier transport in organic disordered materials
Češka, Matěj ; Navrátil, Jiří (referee) ; Weiter, Martin (advisor)
This bachelor´s thesis deals with organic materials for use in photovoltaic energy conversion. A theoretical part of this thesis contains brief introduction to organic photovoltaics. Thin organic films were prepared and were characterized by optical methods and by current voltage characteristics. It was found that the light illumination can improve conductivity of prepared thin layers.
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