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Ongoing efforts to improve the efficiency of organic photovoltaic cells emphasize the significance of the architecture of molecular assemblies in thin films, at nanometer and micron length scales, to enhance both exciton diffusion and charge transport, in donor and acceptor layers. Controlled growth of molecules via self-assembly techniques presents new opportunities to develop nano-structured organic thin films for electronic devices. This thesis is focused on controlling the orientation of phthalocyanine molecular assemblies in thin films in order to demonstrate the impact of microscopic control of molecular order on electrical properties and organic solar cell device performance.The studies performed here provide insights into the self-assembling behavior, film morphology, nanoscale electrical conductivity, and photovoltaic properties of a disk-shaped peripherally substituted phthalocyanine (Pc) molecule possessing amide functional groups in the side chains. Amide functionality was integrated in the side chains of this phthalocyanine molecule with the purpose of increasing the intra-columnar interaction through formation of a hydrogen bonding network between molecules, and to guide columnar orientation in a preferred direction via specific surface-molecule interactions. It is realized that molecule-substrate interactions must dominate over molecule-molecule interactions to achieve control over the deposition of molecules in a preferred direction for organic solar cell applications. Microscopic imaging and spectroscopic studies confirm the formation of flat-lying, well ordered, layered phthalocyanine films as anticipated.The remarkable electrical conductivity of the flat-lying phthalocyanine molecules, as studied by Conducting tip Atomic Force Microscopy (C-AFM) provide the impetus for the formation of organic solar cells based on layers of these hydrogen bonding phthalocyanine molecules. The photocurrent from devices that are made with the ordered Pc molecules and disordered Pc molecules as the primary photoactive donor layer, and vacuum deposited C60 as the acceptor material, were evaluated. The results presented here demonstrate the feasibility of increasing the photogenerated current by controlling the molecular organization in the photo active layer.

O laser é uma fonte de radiação não ionizante altamente concentrada que em contato com diferentes tecidos resulta, de acordo com o tipo de laser, em efeitos térmicos, fotoquímicos e não lineares. Atualmente, o laser tem sido rotineiramente empregado em diversas áreas da ciência, assim como na Medicina e Odontologia. Os tratamentos com utilização de radiação a laser de baixa intensidade na odontologia são de grande interesse para as áreas de cirurgia buco-maxilo-facial e implantodontia sendo usado para a estimulação do processo de osteogênese. Um novo tratamento promissor envolve o processo fotodinâmico e emprega a combinação de dois agentes terapêuticos: um fármaco fotossensível e uma baixa dosagem de luz visível que combinados em presença de oxigênio provocam a bioestimulação celular. É um método eficiente, não-invasivo. Avaliar a utilização do fármaco fotossensível derivado das ftalocianinas com a ftalocianina de cloro-alumínio para o uso no tratamento para estimulação da osteogênese é o objetivo deste trabalho, será avaliado também a potencialidade terapêutica do processo. Na tentativa de se obter melhores resultados com esses fármacos, tem surgido nos últimos anos um interesse muito grande no desenvolvimento de formulações nanoestruturadas, dentro de uma linha altamente emergente de pesquisa a Nanobiotecnologia. Neste contexto, surge dentre os vários sistemas de veiculação disponíveis, as nanoemulsões, que permitem solubilizar fármacos hidrofóbicos em água, mantendo suas características físico-químicas. / The laser is a source of non ionizing radiation highly concentrated and coherent that in contact with different tissues induce thermal, photochemical and non-linear effects according to the type of the laser. Currently, the laser has been used routinely in many areas of science, as well as in medicine and dentistry. The treatments using laser radiation of low intensity in dentistry are of great interest specially in the areas of surgery bucco-maxillo-facial and dental implants and its being used to stimulate the process of osteogenesis. A promising new treatment in dentistry area involves the photodynamic process and employs a combination of two therapeutic agents: a photosensitizers drug and a low dose of visible light that combined in the presence of oxygen could induce cellular biostimulation. It is an efficient non-invasive method. Evaluate the use of the drug derived system to administrate photosensitizers as phthalocyanine derivatives chlorine-aluminum specifically for the use in treatment and stimulation of the osteogenesis is the main objective of this work. It will be also evaluated the therapeutic potential of the process. In an attempt to obtain better biocompatibility of these drugs it has developed in recent years an additional interest in the development of nanostructured formulations, focused in a highly emerging line of research the Nanobiotechnology. The nanoemulsion formulation was selected to this work. It was showed that the hydrophobic drugs choose for this work maintaining its photophysical and chemical characteristics in this medium applicable to biological tissue.

A Terapia Fotodinâmica (TFD) é uma modalidade terapêutica inovadora para o tratamento de tumores cutâneos. As ftalocianinas têm sido utilizadas como fotossensibilizantes sistêmicos devido à sua alta afinidade ao tecido tumoral e seu efeito acentuado quando irradiadas com luz. No entanto, a lipossolubilidade e o baixo coeficiente de partilha óleo/água dessas substâncias dificultam sua aplicação tópica, levando ao desenvolvimento de derivados carregados, como a zinco ftalocianina tetrassulfonada (ZnPcS4) na tentativa de aumentar sua solubilidade em água, bem como melhorar sua captação pelas células tumorais. Entretanto, moléculas carregadas têm dificuldades em atravessar o estrato córneo (EC), a principal barreira da pele. Como a iontoforese é uma técnica não-invasiva capaz de aumentar e controlar a penetração de moléculas carregadas na pele, ela parece ser uma alternativa para aumentar a penetração cutânea da ZnPcS4 nas camadas da pele onde os tumores estão presentes. Dessa forma, foram realizados experimentos in vitro de iontoforese de um gel hidrofílico da ZnPcS4 aplicado topicamente na presença e ausência de NaCl. Estudos de iontoforese in vivo também foram realizados, empregando ratos Wistar como modelo animal, bem como experimentos em cultura de células tumorais para avaliar a citotoxicidade do fármaco em estudo. O método analítico para quantificação do fármaco na pele foi validado quanto à linearidade, precisão, exatidão, sensibilidade e seletividade. A iontoforese catódica promoveu um aumento significativo da retenção da ZnPcS4 tanto no EC como na epiderme viável nos experimentos realizados na presença e ausência de NaCl em relação à aplicação passiva da formulação e de iontoforese anódica, sendo que ocorreu um aumento da quantidade do fármaco retido nas diferentes camadas da pele quando o sal foi retirado da formulação. Os estudos in vivo com a formulação também mostraram que a corrente elétrica aumentou a penetração do fármaco para as camadas mais profundas da pele em relação aos experimentos passivos de permeação, o que foi evidenciado pela intensidade de fluorescência do fármaco visualizada por microscopia confocal e pela quantidade de fármaco retido nas diferentes camadas da pele. Resultados em cultura de células tumorais A431 sugerem que a concentração de fármaco que chega à epiderme viável após experimentos de iontoforese catódica é capaz de matar mais de 90% dessas células tumorais quando a dose de irradiação de 5 J/cm2 é aplicada. Além disso, quando a corrente elétrica é aplicada em cultura celular, não foi observado nenhum aumento significativo da citotoxicidade da ZnPcS4, demonstrando que a aplicação de corrente elétrica não fez com que a entrada do fármaco para o interior das células tumorais aumentasse. Não restam dúvidas, no entanto, que a corrente elétrica aumentou a penetração do fármaco nas camadas profundas da pele, além de levar a uma distribuição homogênea da ZnPcS4 nessas camadas após 15 minutos de aplicação. / Photodynamic therapy (PDT) is an innovative therapeutic modality for the treatment of cutaneous tumors. The phthalocyanines have been used as systemic photosensitizing agents due to its high affinity to tumor tissues and its accentuated effect when irradiated with light. However, the lipophilicity and the low partition coefficient oil/water of these substances difficult its topical application, leading to the development of charged derivatives, such as the zinc phthalocyanine tetrasulfonated (ZnPcS4) in an attempt to increase the water solubility, as well as improve the drug uptake by tumor cells. However, charged molecules have difficulties to cross the stratum corneum (SC), the main barrier of the skin. As iontophoresis is a noninvasive technique able to improve and control the penetration of charged molecules through the skin, it seems to be an alternative for enhancing ZnPcS4 penetration into the deep layers of the skin, where cutaneous tumors reside. This way, in vitro iontophoresis experiments of a hydrophilic gel containing ZnPcS4 applied topically in the presence and absence of NaCl were performed. In vivo iontophoresis studies were also carried out employing Wistar rats as animal model, as well as experiments in culture of tumour cells to evaluate the cytotoxicity of the drug. The analytical method for the quantification of the drug in the skin was validated considering the parameters of linearity, precision, accuracy, sensitivity and selectivity. The cathodal iontophoresis promoted a significant increase in retention of ZnPcS4 in both SC and viable epidermis in the experiments conducted in the presence and absence of NaCl in relation to the formulation applied passively or by anodal iontophoresis. Therefore, there was an increase in the amount of the drug retained in different layers of the skin when salt was removed from the formulation in the cathodal iontophoresis. In vivo studies also demonstrated that the electrical current increased penetration of the drug to the deeper layers of the skin in relation to passive experiments, evidenced by the fluorescence intensity of the drug showed by confocal microscopy and by the amount of drug retained in the different layers of the skin. Results with A431 tumor cells suggest that the concentration of the drug that reaches the viable epidermis after cathodal iontophoresis is able to kill more than 90% of these tumor cells when the radiation dose of 5 J/cm² was applied. In addition, when the electric current was applied to the cells, it was not observed any significant increase of cytotoxicity, demonstrating that the electric current application did not increased the uptake of the ZnPcS4 by the tumor cells. There are no doubts, however, that the electric current increased the ZnPcS4 penetration to the deep layers of the skin and lead to a homogeneous distribution of ZnPcS4 in these layers after 15 minutes of application.

Organic semiconductor interfaces are promising materials for use in next-generation electronic and optoelectronic devices. Current models for metal-organic interfacial electronic structure and dynamics are inadequate for strongly hybridized systems. This work aims to address this issue by identifying the factors most important for understanding chemisorbed interfaces with an eye towards tuning the interfacial properties. Here, I present the results of my research on chemisorbed interfaces formed between thin-films of phthalocyanine molecules grown on monocrystalline Cu(110). Using atomically-resolved nanoscale imaging in combination with surface-sensitive photoemission techniques, I show that single-molecule level interactions control the structural and electronic properties of the interface. I then demonstrate that surface modifications aimed at controlling interfacial interactions are an effective way to tailor the physical and electronic structure of the interface. This dissertation details a systematic investigation of the effect of molecular and surface functionalization on interfacial interactions. To understand the role of molecular structure, two types of phthalocyanine (Pc) molecules are studied: non-planar, dipolar molecules (TiOPc), and planar, non-polar molecules (H2Pc and CuPc). Multiple adsorption configurations for TiOPc lead to configuration-dependent self-assembly, Kondo screening, and electronic energy-level alignment. To understand the role of surface structure, the Cu(110) surface is textured and passivated by oxygen chemisorption prior to molecular deposition, which gives control over thin-film growth and interfacial electronic structure in H2Pc and CuPc films. Overall, the work presented here demonstrates a method for understanding interfacial electronic structure of strongly hybridized interfaces, an important first step towards developing more robust models for metal-organic interfaces, and reliable, predictive tuning of interfacial properties.

Úlceras são alterações que ocorrem na integridade da pele como consequência de lesões diversas, constituindo a dificuldade de sua cura um grave problema de saúde pública. A fototerapia com laser de baixa intensidade (LLLT), através de seus efeitos biomoduladores, vem sendo apontada como uma técnica prática, rápida e eficaz para esses casos. Entretanto, aplicações de LLLT podem, em alguns casos, estimular a proliferação de microrganismos patogênicos presentes na lesão, resultando numa piora da infecção e maior retardo no processo de reparo. Nesses casos, o uso de quimioterapia fotodinâmica antimicrobiana (PACT) pode ser uma alternativa. O presente estudo testou a eficácia da PACT com Ftalocianina Cloro-Alumínio (FC-ClAl) e da LLLT na inativação de microrganismos, com uma dose energética adequada para não prejudicar o processo de cicatrização. Em biofilmes de P. aeruginosa e S. aureus previamente cultivados por um período de 24 h em microplacas de 24 e 96 poços, realizou-se etapa única de aplicação da fototerapia LLLT e PACT com 4 diferentes formulações para inativação de microrganismos: formulação vazia (ausência de fármaco fotossensível FV), formulação catiônica vazia (com alteração em sua polaridade FCV), formulação aniônica com fármaco fotossensível (apenas Ftalocianina Cloro-alumínio FC-ClAl FAPc), formulação catiônica com fármaco fotossensível (FC-ClAl + formulação com polaridade alterada FCPc). Foram feitas análises quantitativas através da contagem de células viáveis e medidas de absorbância em leitora de ELISA com sal tetrazólio, 3-(4,5-dimethylthiazol-2-yl)-2,5-difenil brometo de tetrazólio (MTT), associado. Os dados obtidos foram comparados através de análise de variância (ANOVA) com nível de confiança de 95%. Os resultados obtidos permitiram concluir que a PACT com FC-ClAl sozinha (FAPc) não apresenta ação bactericida satisfatória sobre a P. aeruginosa e a S. aureus, mostrando resultados estimulatórios a esses microrganismos quando comparada às outras 3 formulações utilizadas. A ação antimicrobiana só foi observada ao se ter a associação da PACT Ftalocianina cloro-alumínio com a formulação catiônica (FCPc), a qual mostrou intensa interação com os biofilmes microbianos, principalmente com a S. aureus, mesmo na ausência de Ftalocianina (FCV). / Ulcers are changes on the skin integrity as a consequence of several lesions, and its cure represents a serious public health problem. Phototherapy based on low level laser therapy (LLLT), through its biomodulatory effects, has been pointed as a fast, practical and effective therapy for these cases. However, LLLT applications may, in some cases, stimulate pathogenic microorganisms proliferation present in the lesion, resulting in a worst infection and longer delay on the healing process. For such cases the use of Photodynamic Antimicrobial Chemotherapy (PACT) can be an alternative. The present study tested the PACT effectiveness with a phthalocyanine-derived photosensitizer and LLLT on microorganism inactivation, with an adequate energy dose in order to not damage all the healing process. On P. aeruginosa and S. aureus mature biofilms, previously cultivated for a period of 24 h in 24 and 96 wells-plate, a single application of phototherapy based on LLLT and PACT to inactivate bacteria was performed, with four different formulations: blank formulation (FV - no photosensitive drug), cationic empty formulation (FCV - formulation with an inverted polarity), formulation with anionic photosensitive drug (FAPc - only Chloro-aluminum Phthalocyanine) and cationic formulation with photosensitive drug (FCPc - Chloro-aluminum Phthalocyanine associated with an inverted polarity formulation). Quantitative analyses were performed through the counting of colony forming units (CFU) and the absorbance analysis with MTT associated. The data were compared through variance analysis test (ANOVA), with a confidence level of 95%. The results showed that PACT with Chloro-aluminum Phthalocyanine itself does not present satisfactory bactericidal effect against P. aeruginosa and S. aureus. This photosensitizer (FAPc) presented a microorganism stimulatory action when compared with the other three formulations used. The bactericidal effect was seen only with the PACT with cationic formulation association, which demonstrated an intense interaction with microbial biofilms, especially with S. aureus, even in the absence of Phthalocyanine (FCV).

Simple Photochemical Reduction of Carbon Dioxide to Formate Ovuokenye Omadoko, Department of Chemistry, East Tennessee State University, Johnson City, Tennessee. There is a need to develop techniques for conversion of carbon dioxide to other useful products such as methanol, formaldehyde, formic acid, formate, methane, and hydrocarbons. Carbon dioxide can be converted into these products using different methods such as photochemical, electrochemical, thermochemical and hydrogenation by bacteria. Formate is of interest due to having wide industrial applications which include use in direct liquid fuel cells (DLFC’s), an additive in pyrolysis vapors, precursor for biological fuels, and is a key intermediate in methanogenesis breaking down complex organic compounds. In this work, conversion of carbon dioxide to formate was accomplished photochemically. The concentration of formate obtained was quantified using ion chromatography. The yield of formate, based on the amount of carbon dioxide in solution, was 1.54%, while the quantum yield near 1.0%. Detailed studies of the photoreduction process showed that amount of sensitizer, light intensity and pH affect the amount of formate generated.

Over the past few decades, metal phthalocyanines (MPcs) have been thoroughly investigated as active materials in organic field-effect transistors (OFETs) towards the commercialization of flexible integrated circuits and displays. One of several advantages to MPcs as building blocks for OFETs is the high degree of functionality, from which the choice of metal ion, substituents along with the phthalocyanine framework and axially bound ligands can synergistically tune the physical and self-assembly properties of the material. Recent interest has been directed to the introduction of main-group elements as the central ion of MPcs as an avenue to install both hole and electron transport properties and improve device performance. To prepare materials that are suitable to be employed as the semiconducting active layer in organic field-effect transistors, a family of novel silicon phthalocyanine derivatives was prepared. The synthesis and optoelectronic properties of those new axially disubstituted silicon phthalocyanines are detailed in this work. Axial ligand variation mainly includes alkylsiloxy derivatives. The emphasis of the current thesis, however, is on tailoring the Pc backbone, which includes replacing the four benzene units with pyrazine moieties, extending the degree of conjugation with naphthalene, and introducing substituents on their peripheral positions. Several metal-containing tetra-2,3-pyrazinoporphyrazines are also described, but their applications are limited due to the difficulty of purification. Specifically, Chapter 1 serves as a comprehensive review of main-group phthalocyanines and their use as active materials in organic field-effect transistors. In Chapter 2, silicon tetra-2,3-pyrazinoporphyrazine complexes are explored. The isosteric substitution of CH groups in Pc macrocycle for nitrogen atoms leads to an obvious hypsochromic shift in their main absorption band, and their relatively low energy levels make them promising air-stable n-type organic semiconducting materials for OFETs. The synthesis and characterization of silicon tetra(tert-butyl)-2,3-naphthalocyanine complexes are described in Chapter 3. The extension of π-conjugation leads to obvious bathochromic shifts in the main absorption band. In addition, the introduction of tert-butyl groups on the periphery of the molecule reduces the tendency of the naphthalocyanine molecules to aggregate, thereby increase their solubility. Chapter 4 covers the synthesis and characterization of zinc tetra-2,3-pyrazinoporphyrazine and cobalt tetra-2,3-pyrazinoporphyrazine, whereas more future works are expected. The fifth chapter provides a conclusion to this work, and possible future directions of the research conducted herein.

Quantum coherence plays a vital role in the excitonic properties of organic semiconductors. Several theoretical and experimental studies have shown an unprecedented role of coherence in charge transfer and transport processes, which in turn can improve the performance of electronic devices. Specifically, an enhancement of exciton coherence size can result in fast energy transport and efficient charge separation. The ability to tailor the design and performance of organic electronics based on exciton coherence effects represents the possibility of ultrafast electronic applications in communication and information technology. The objective of this thesis is the excitonic coherence studies of 1D crystalline thin films of phthalocyanine-based organic semiconductors using steady-state and time-resolved photoluminescence spectroscopy (TRPL). One of the main focuses of this work is on investigating the correlation of intermolecular interactions, $\pi$ orbital overlap and dynamic disorders on the excitonic coherent behaviors in crystalline thin films of various phthalocyanine derivatives (i.e. H$_2$TPP, H$_2$OBPc, H$_2$OCPc, and H$_2$OBNc). Specifically, coherence lengths, exciton-phonon coupling strengths and the nearest neighbor (NN) interaction strengths are determined via: (1) the PL ratio of the excitonic coherence transition and its first vibrational replica and (2) the temperature evolution of radiative recombination lifetimes of coherent excitons. This study showed that the optimum coherence size and the robustness of excitonic coherence can be achieved by a complex interplay between NN interaction, vibrational energies and the coupling to vibrational modes. In particular, it is shown that the shortest NN distance does not ensure the achievement of maximum coherence length within the four investigated phthalocyanine species. Instead, the largest coherence length is measured in the octabutoxy derivative, where the saddle shape of the molecule and crystalline packing results in weaker coupling to the acoustic phonons modes despite having larger intermolecular NN distance. In addition, the effect of static and dynamic disorders on the behavior of exciton coherence is explored by alloying two phthalocyanine derivatives that are close in band gap energies and possess large coherence lengths, H$_2$OBPc and H$_2$OBNc. This study demonstrated the successful tuning of exciton coherence lengths and excitonic parameters in organic analogues of semiconductor alloys, H$_2$OBNc$_x$H$_2$OBPc$_{1-x}$. Furthermore, the correlation of exciton-phonon coupling and radiative recombination rate of coherent excitons with increasing alloy concentration or static disorders are successfully revealed.

This thesis is focused on adsorption of phthalocyanines on tin and indium passivated silicon Si(111) surfaces with the √3 × √3 reconstruction at room temperature. Scanning tunneling microscopy was used for obtaining atomically resolved surface images. Molecules on these surfaces predominantly adsorb on Si-substitutional defects. Local density of states (LDOS) of strongly adsorbed molecules was obtained by scanning tunneling spectroscopy. The origin of fuzzy imaging of molecules sitting on Si-substitutional double defects was probed. Voltage dependence of mean lifetime of two observed states, between which the "fuzzy" molecule is switching, was measured by analysis of tunneling current fluctuations. We discussed the influence of external parameters on the switching between the two states. We attribute the fuzzy behaviour of the molecule and resulting tunneling current fluctuations to the motion of the molecule in a double-well potential and propose two most likely kinds of the motion which most closely agree with the obtained data.