Gegenstand der vorliegenden Arbeit ist die Synthese und Charakterisierung neuartiger elektrophiler Barbiturate. In diesen Zielverbindungen sollte die kovalente Verknüpfung eines elektrophilen bzw. Lewis-aciden Zentrums mit einer Wasserstoffbrückensequenz realisiert sowie deren gegenseitige Beeinflussung untersucht werden. Im Mittelpunkt standen dabei Barbitursäure-funktionalisierte Triarylmethylium-Ionen sowie Merocyanine. Die Charakterisierung der synthetisierten Verbindungen erfolgte mittels NMR-Spektroskopie, Einkristall-Röntgenstrukturanalyse sowie solvatochromen Messungen. Besonderes Augenmerk lag auf der Wechselwirkung mit verschiedenen Rezeptoren über Wasserstoffbrückenbindungen, wobei sowohl die Anzahl als auch die Stärke der Wasserstoffbrücken variiert wurden. Die Reaktion der elektrophilen Barbiturate mit ausgewählten Nucleophilen wurde NMR- und UV/Vis-spektroskopisch verfolgt. In ternären Systemen bestehend aus Elektrophil, Nucleophil und Rezeptor wurde systematisch der Einfluss der Komplexierung über Wasserstoffbrücken auf die Gleichgewichts- und Geschwindigkeitskonstante der Elektrophil-Nucleophil-Rekombination erfasst. Daneben erfolgte die Bestimmung der Nucleophilie-Parameter substituierter Barbiturat-Anionen unter Berücksichtigung des ambidenten Verhaltens dieser Nucleophile.

Die Entwicklung von makrocyclischen Chelatoren, die mit Kupferionen thermodynamisch stabile und kinetisch inerte Komplexe bilden, ist in den letzten Jahren zunehmend in den Fokus der Forschung gerückt. Das ergibt sich insbesondere aus der Möglichkeit, Radiokupfernuklide aufgrund günstiger kernphysikalischer Eigenschaften sowohl für diagnostische (64Cu) als auch therapeutische (67Cu) Anwendungen einzusetzen. Hervorzuheben ist der Azamakrocyclus Cyclam (1,4,8,11-Tetraazacyclodecan), da dieser mit Kupfer(II)-Ionen Komplexe hoher thermodynamischer Stabilität bildet. Zudem weist der Chelator weitere Funktionalisierungsmöglichkeiten auf, um in Hinblick auf eine nuklearmedizinische Anwendung pharmakologisch relevante Moleküle wie beispielsweise Peptide oder Proteine (Antikörper oder Antikörperfragmente) kovalent zu binden und damit eine spezifische Anreicherung im Tumorgewebe zu ermöglichen. Allerdings erfordert das Maßschneidern der Eigenschaften von neuen bifunktionellen Chelatoren Kenntnisse über den Einfluss der Substituten auf die Stabilität der gebildeten Kupfer(II)-Komplexe. Die thermodynamische Stabilität lässt keine Aussagen über das Verhalten in vivo zu. Die Ursache für die kinetische Labilität in Säugetieren ist noch nicht vollständig verstanden, wird aber u. a. auf kupferbindende Enzyme bzw. Proteine zurückgeführt. Die Bioverteilung der Radiokupferkomplexe wird aber auch von weiteren Parameter, wie Hydrophilie, Ladung und Polarisierbarkeit beeinflusst. Mit dieser Arbeit wurde ein wesentlicher Beitrag zur Entwicklung von 64Cu Chelaten auf Basis von Cyclam-Propionsäure-Liganden geleistet. Diese Stoffklasse ist bisher synthetisch wenig erschlossen und Radiokupfer-markierte Komplexe zudem bisher gar nicht beschrieben. Daher ist es von besonderem Interesse die kinetische Stabilität Radiokupfer-markierter Cyclam-Propionsäure-Derivate zu untersuchen und mit einer Reihe bekannter Radiokupfer-markierter Cyclam-Essigsäure-Komplexe zu vergleichen. Es wurden vier N-funktionalisierte Cyclam-Derivate 13, 14b, 15 und 16, die eine unterschiedliche Anzahl an Propionsäuregruppen tragen, erfolgreich synthetisiert und in sehr hoher Reinheit (>99%) isoliert. Besonders hervorzuheben ist die erstmalige Synthese des trans-N,N´´-funktionalisierten Cyclam-Propionsäure-Derivates 14b in hoher Ausbeute (gesamt = 32%). Von den Verbindungen 13, 14b, 15 und 16 sind entsprechende Kupfer(II)-Komplexe hergestellt worden. Zur Aufklärung relevanter Fragestellungen bezüglich der chemischen und geometrischen Eigenschaften sind verschiedene spektroskopische Methoden (Röntgeneinkristallstrukturanalyse, IR, UV/VIS, Elektronenspinresonanz-Spektroskopie) anhand von den isolierten Kupfer(II)-Komplexen CuII-13, CuII-14b und CuII-16 herangezogen worden. Die röntgenkristallografischen Strukturaufklärungen der Komplexe CuII-14b und CuII-16 weisen eine verzerrt quadratisch-pyramidale Koordinationsgeometrie auf. Das Ligandenfeld wird innerhalb der Stickstoffebene mit steigendem Substitutionsgrad schwächer. Das wurde auch durch ESR-Messungen bestätigt. Nachweislich verursachen die zusätzlichen funktionellen Gruppen eine kleinere Ligandenfeldaufspaltung. Weiterhin nahm die kinetische Stabilität unter stark sauren Bedingungen mit steigendem Substitutionsgrad ab. Der Vergleich mit den bekannten oktaedrischen Kupfer(II)-Cyclam-Essigsäure-Komplexen zeigt, dass die quadratisch-pyramidalen Kupfer(II)-Cyclam-Propionsäure-Derivate unter stark sauren Bedingungen schneller dissoziieren. Als Ursache können die unterschiedlichen Konfigurationen diskutiert werden, da bei 4N+2-Geometrien die thermodynamisch bevorzugte trans III-Konfigurationen gebildet wird. Radiochemische Untersuchungen zur Bewertung der kinetischen Stabilität in vitro und in vivo sind mit den 64Cu-markierten Liganden 13, 14b, 15 und 16 durchgeführt worden. Hierfür ist ein In-vitro-Stabilitätstest basierend auf dem kupferbindenden Enzym Superoxid-Dismutase (SOD) bzw. humanem Serum für radiomarkierte Verbindungen entwickelt worden. In humanem Serum ist Albumin (~66 kDa) in sehr hoher Konzentration enthalten und eines der wichtigsten Transportproteine für extrazelluläre Kupfer-Ionen. Aufgrund seiner Abundanz im Blutplasma ist im Serum-Assay jeweils nur eine stark ausgeprägte Bande bei ca. 66 kDa detektiert worden. Dieser etablierte In-vitro-Stabilitätstest beruht im Gegensatz zu anderen herkömmlichen Analysemethoden (Radio-HPLC oder Radio-DC) auf dem Prinzip der Gelelektrophorese. Von großem Vorteil ist, dass mehrere Proben simultan untersucht werden können und die Ergebnisse zuverlässig und reproduzierbar sind. Die In-vitro-Ergebnisse zeigen einen ähnlichen Trend wie bei der säure-assoziierten Dissoziation, wobei die höchste Stabilität bemerkenswerterweise bei dem [64Cu]Cu-14b Komplex bestimmt wurde. Allerdings beruht der Mechanismus hier nicht auf einer Dissoziation sondern auf einer Transchelatisierung. Die Ergebnisse der Bioverteilungen in Wistar-Ratten korrelieren mit den In-vitro-Studien in humanem Serum. Der Komplex [64Cu]Cu 14b zeigte sowohl eine schnelle renale Blut-Clearence als auch eine sehr geringe Anreicherung in der Leber und stellt damit eine Alternative zu den kommerziell erwerblichen Liganden dar. Als geeignete Chelatoren bieten Cyclam-Monopropionsäure 13 und Cyclam-Dipropionsäure 14b die Möglichkeit, Radiokupfernuklide stabil zu binden und erlauben die mehrfache Einführung von EGFR-spezifischen Peptiden an das Grundgerüst. Als Grundgerüst wurde der Ligand 13 ausgewählt. Durch die Multifunktionalisierung sollen höhere Affinitäten zum Rezeptor und verbesserte metabolische Stabilitäten hervorgerufen werden. Für diese Verbindung liegen erste vielversprechende Ergebnisse vor, wobei hohe Affinitäten zu zwei EGFR-positiven Zelllinien bestimmt wurden.

Kohlenstoffnanoröhren (engl. carbon nanotubes, CNT)-Polymer-Komposite haben ein großes Potential im Bereich sensorischer Anwendungen. Dabei spielen die elektrischen Eigenschaften des Komposits und deren Änderungen unter mechanischer Belastung eine entscheidende Rolle. Einen maßgeblichen Einfluss nimmt dabei das Aspektverhältnis der CNT-Agglomerate sowie der CNTs selbst ein, welches jeweils vom CNT-Desagglomerationsprozess bestimmt wird. Die Dispergierung beeinflusst folglich auch die elektrische Leitfähigkeit und Reproduzierbarkeit des Komposits sowohl im mechanisch unbelasteten als auch belasteten Zustand. Dies wurde anhand von (teil-)analytischen Modellen gezeigt. Die Dispersionsqualität wird dabei von vielen Faktoren beeinflusst, wobei die Prozessparameter beim Ultraschalldispergieren derzeit nach der Trial-and-Error-Methode bestimmt werden. Im Rahmen der Arbeit wurde eine Dispergiergleichung für zylindrische Partikel, die CNTs näherungsweise sind, erstmals für die Dispergierung von CNTs in Lösungsmitteln entwickelt, angewendet sowie verifiziert. Die Gültigkeit der Gleichung für CNTs wurde durch Variation der Ultraschallparameter Zeit sowie Energie und deren Einfluss auf den Dispergiergrad gezeigt. Die mittels UV-VIS-Spektroskopie gemessene Extinktion diente dabei als indirekte Messgröße des Dispergiergrads. Nach Vorversuchen zur geeigneten Materialauswahl wurden alle relevanten Einflussparameter berechnet oder experimentell bestimmt. Die experimentelle Verifikation erfolgte an CNT-N-Methyl-2-pyrrolidon-Dispersionen, die mittels Ultraschallsonotrode kontrolliert dispergiert wurden. Im Ergebnis wurde gezeigt, dass die Bestimmung der optimalen Ultraschallparameter möglich ist und die bis dahin übliche Praxis der experimentellen Bestimmung der Dispergierparameter für CNTs ablösen kann. Mithin wurde die Grundlage für die Herstellung elektrisch reproduzierbarer CNT-Polymer-Komposit-basierter Sensoren gelegt. Darüber hinaus wurde das Anwendungspotential dieses Sensorkonzepts für Einzelsensoren zur punktuellen Druckmessung über eine Druckverteilungsmessung als Sensormatrix bis hin zur Anwendung als Einlegesohle im Schuh zur Überwachung des Drucks gezeigt. / Carbon nanotubes (CNT) polymer composites in the field of sensory applications have considerable potential. However, their electrical properties and their changes under mechanical stress play a decisive role. The deagglomeration process of the CNTs also has a great influence on the aspect ratio of the CNT agglomerates as well as the CNTs themselves and thus the electrical conductivity and reproducibility of the composite in both the mechanically unloaded and loaded state.This is shown by means of (partially) analytical models. The dispersion quality is influenced by many factors. The process parameters during ultrasound dispersion are currently being determined by a trial-and-error method. Within the scope of the work, a dispersing equation for cylindrical particles, which are approximate to CNTs, was first developed, applied and verified for the dispersion of CNTs in solvents. The validity of the equation for CNTs was shown by the variation of the ultrasonic parameters time as well as energy and their influence on the degree of dispersion. The absorbance measured by means of UV-VIS spectroscopy serves as an indirect measure of the degree of dispersion. After pre-testing for suitable material selection, all relevant influencing parameters were calculated or determined experimentally. Experimental verification was carried out on CNT-N-methyl-2-pyrrolidone dispersions, which were dispersed in a controlled manner by means of an ultrasonic sonotrode. As a result, it is illustrated that the determination of the optimal ultrasonic parameters is possible and can replace the conventional practice of the experimental determination of the dispersing parameters for CNTs. Accordingly, the basis for the production of electrically reproducible CNT polymer composite-based sensors has been established. In addition, the application potential of this sensor concept ranging from individual sensors for selective pressure measurement over pressure distribution measurement as a sensor matrix to the application as a shoe insole for pressure monitoring was shown.

This Diploma thesis is focused on physical and chemical effects which contribute to the decomposition of organic dyes by diaphragm discharge generated in water solutions. Due to the application of DC high voltage source in continuous regime, there is an effect of electrolysis contributing to the dye decomposition by diaphragm discharge. The aim of this work was to find out when the electrolysis is running (or when is the moment of discharge breakdown) and which factors influence the breakdown. The other goal was decomposition of selected textile and food organic dyes by electrolysis itself. In the theoretical part, theory about creation of electrical discharges in aqueous solutions is noted and various types of underwater discharges are described. Background researches about underwater electrical discharges used in the world are mentioned as well as the use of diaphragm discharges and various ways how to remove organic dyes from wastewater. Finally, theories of electrolysis, UV-VIS spectroscopy and basis of other analytical methods useful for detection of organic molecules are described. Experimental part is oriented to experiment procedure which was carried out in a reactor with separated electrode areas. Separation was made by dielectric diaphragm with a pinhole in the centre. Its initial diameter was 0.4 mm. Used chemicals and course of experiments are described in this part, too. First, the breakdown moment in the reactor was investigated (i. e. determination, when only electrolysis was operating) by formation of hydrogen peroxide and measurement of dynamic (time resolved) electrical characteristics. Next, decomposition of selected dyes by electrolysis was carried out. As the decomposition was related to decolorization of the solution, UV-VIS spectroscopy in the range of 350–700 nm was used for determination of dye concentration. Next part focused on results presents various factors which had an effect on breakdown of diaphragm discharge. These factors are kind of used electrolyte, initial conductivity of solution, kind of dye, temperature of solution and type of reactor (or solution volume). From the result, the most important factor is initial solution conductivity. After the determination of the breakdown moment, the electrolysis of organic dyes was performed. The applied current was 10 mA, initial conductivity was 500 µS/cm and used electrolyte was NaCl. Moreover comparison of dye decomposition in dependence on the different applied power was realized. From this comparison one can assume, there is no significant contribution of electrolysis (the efficiency is approximately 15 %) to the diaphragm discharge in aqueous solution.

Actuellement, les photochromes photoréversibles présentent un intérêt important en vue de leurs applications éventuelles comme interrupteurs optiques ou pour le traitement et le stockage de données. L’objectif principal de ce travail de thèse a été d’évaluer les 3-­-(2-­-benzylbenzoyl)-­-4-­-quinolones en tant que système photochromique photoréversible. Afin d’étudier la relation entre la structure chimique et le comportement photochromique de ce système, une série de nouvelles 3-­-(2-­-benzylbenzoyl)-­-4-­-quinolones à substitution variée a été préparée à l’aide de procédures connues ainsi qu’élaborées lors de ce travail. La photoréaction de ces nouveaux molecules étant très complexe, une méthode d’étude a été établie avec des 2-­-benzyl-­-3-­-benzoyl-­-4-­-quinolones photoénolisables au comportement plus simple. Leurs spectres d’absorption modélisés à l’aide de fonctions pekariennes ont été comparés avec les résultats des calculs quantiques. Le mécanisme selon lequel la réaction de décoloration se fait par l’ionisation des photoénols fortement acides via protonation des molécules du solvant a été établi. Enfin, la troisième partie est consacrée à l’étude des nouveaux dérivés de quinolones. D’après l’analyse de leurs spectres d’absorption, ainsi que les résultats des calculs quantiques, nous proposons un mécanisme où le transfert d’hydrogène photo-­-induit conduirait à la formation d’un intermédiaire biradicalaire, capable de se cycliser en dibenzo[b]acrydinones hydroxysubstituées. Un tel mécanisme expliquerait la forte influence qu’ont la nature des substituants en positions 1 et 2, ainsi que la température et la présence d’oxygène sur la régio-­- et stéréo-­-sélectivité de cette photoréaction. / Photoreversible photochromic compounds are currently of considerable interest from the point of view of their potential applications as molecular switches and for data storage and processing. The main target of the present investigation is to evaluate the scope and limitations of 3-­-(2-­-benzylbenzoyl)-­-4-­-quinolones as a photoreversible photochromic system. In order to investigate the relationship between quinolone chemical structures and photochemical behavior, a large series of new 3-­-(2-­-benzylbenzoyl)-­-4-­-quinolones with different substituents has been prepared using known as well as newly elaborated synthetic procedures. In the second part of the work a series of simpler photoenolizable 2-­-benzyl-­-3-­-benzoyl quinolones is studied by the means of fitting their UV-­-Vis absorption spectra and comparison with the results of quantum mechanical calculations at the TD DFT level. It was concluded that the mechanism of the reverse reaction involves ionization of the strongly acidic photoenols via protonation of the solvent molecules. The third part of the work includes investigation of the new quinolone derivatives. From the analyses of their absorption spectra and the results of quantum mechanical calculations, we propose a tentative mechanism, according to which the photoinduced hydrogen transfer yields a biradical, capable of cyclization into the hydroxy substituted dibenzo[b]acrydinones. This mechanism accounts for the observation that the nature of substituents in positions 1 and 2, the temperature and the presence of oxygen strongly affect regio-­- and stereoselectivity of the cyclization.

New complex silicon-containing molecules were made by B(C6F5)3-catalyzed hydrosilation, dehydrocoupling, and dealkylative coupling reactions starting from Si-H reagents. The scope of reactions starting from disilane was expanded to include the formation of silicon-sulfur1, silicon-oxygen and silicon-alkyl side-chains. Reaction inhibition was found with some heteroatom substrates, such as phenols and imines, that strongly bound to B(C6F5)3, and was consistent with the proposed mechanism (Chapter 2). B(C6F5)3 was found to be selective for Si-H activation in reactions of disilane and no competing Si-Si bond cleavage side-reactions were observed. This result will guide future studies and application of B(C6F5)3-catalyzed reactions with polysilanes. A different type of selectivity, the competing B(C6F5)3-catalyzed over-reduction, is evaluated and discussed in Chapter 3. This over-reduction reaction was classified into two distinct cases: alkyl groups for which over-reduction reaction was dependent on the steric bulk of the alkyl group and benzylic groups for which over-reduction was dependent on having an alpha-aryl group. These reactions are consistent with the proposed Piers-Oestreich mechanism (see Chapter 3) and suggest the rate-determining step for over-reduction is the nucleophilic attack of the alkoxysilane (R -O-SiR3) to the R3Si•••H•••B(C6F5)3 complex. Benzylic side-chains were over-reduced regardless of the steric bulk of the aryl groups. Literature precedents suggest that benzyl over-reductions must undergo an alternative mechanism to the Piers-Oestreich mechanism. A number of mechanisms have been proposed in the literature and in Chapter 3, suggesting conventional heteroatom substrate borane or silane-borane complexation. Furthermore, over-reduction of benzylic sulfur containing side-chains was found and this reaction was exploited in the B(C6F5)3-catalyzed synthesis of unique silicon-sulfur silicon-containing products. These over-reduction reactions highlighted the role of the silane for over-reduction and the challenges associated with the post-polymerization modification of poly(phenylsilane). The advances in B(C6F5)3-catalyzed synthesis of small silane molecules suggested reaction conditions and gave spectroscopic benchmarks that were applied to the post polymerization modification of poly(phenylsilane) (Chapter 4). New X-modified poly(phenylsilane) derivatives with thiolato (sulfur), alkoxy/aryloxy (oxygen), amido (nitrogen) and alkyl(carbon) side-chains were prepared with 10-40% incorporation of the ‘X’ group into poly(phenylsilane). These new polysilanes were characterized by the following methods: 1H/13C/29Si NMR, IR, MALS-GPC, EA, and UV-vis absorption spectroscopy. Together, these characterization methods showed that the polysilane had not undergone Si-Si cleavage and thus demonstrated the utility of B(C6F5)3 for the selective activation of Si-H bonds. Thermal decomposition of X-modified poly(phenylsilane) derivatives and parent poly(phenylsilane) showed interesting redistribution pathways (Chapter 5). The thermal decomposition products of poly(phenylsilane) were identified: volatile monosilanes, a structurally complex not-yet-identified phenylsilicon-containing material generated at 500 °C, and a mixture of silicon carbide (SiC) and elemental carbon generated at 800 °C. The B(C6F5)3-catalyzed post-polymerization method (Chapter 4) was evaluated based on the substitution percentage for X-functionalized poly(phenylsilane) derivatives. Reactions of highly electron-donating substrates gave a low amount of X incorporation (10%, e.g. aryloxy side-chains derived from phenol). Aryloxy groups were alternatively introduced via demethanative coupling, which gave a polymer with a greater substitution percentage (25%). The overall impact of the H-to-X substitution reactions was gauged by UV-vis absorption spectra and desirable UV absorption properties would require the modified poly(phenylsilane) to have a high degree of substitution. / Graduate / 2017-09-02

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Submitted by Angela Maria de Oliveira (amolivei@uepg.br) on 2018-06-05T14:40:04Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Schardosin, Janaina.pdf: 3840457 bytes, checksum: ffe3148238384650d2997e09aff27ed0 (MD5) / Made available in DSpace on 2018-06-05T14:40:04Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Schardosin, Janaina.pdf: 3840457 bytes, checksum: ffe3148238384650d2997e09aff27ed0 (MD5) Previous issue date: 2018-04-09 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O processo de humificação, conversão de resíduos orgânicos em húmus, é um fator importante na compreensão da dinâmica da matéria orgânica. A sua quantificação, é fundamental para o estudo da evolução química dessa substância. O objetivo deste trabalho foi caracterizar as amostras de ácidos húmicos (AHs) e quantificar o grau de humificação do solo e das frações físicas (por tamanho de partículas). As análises de Espectroscopias de Fluorescência de Raios X por Dispersão de Comprimento de Onda, Fluorescência na região do Visível, Espectroscopia Vibracional na região de Infravermelho e de Absorção na região do Ultravioleta e Vísivel, Espectrocospia Raman, acompanhadas das técnicas de Análise Térmica, Microscopia Eletrônica de Varredura com Canhão Eletrônico por Efeito de Campo e Espalhamento Dinâmico da Luz foram utilizadas. A quantificação do grau de humificação mostrou que AHs extraídos da profundidade (10- 20 cm) possuem estruturas aromáticas mais condensadas. A fração de AH que apresentou maior grau de humificação foi a extraída do solo com a adição de calagem, o que demonstra uma influência do calcário na aceleração do processo de humificação. O estudo das frações granulométricas do solo, determinou, com espectroscopia de infravermelho, os atributos orgânicos que estão associados as frações do solo e, que a maioria dos minerais presentes nas frações granulométricas, foram identificados como sendo caulinita, haloisita, quartzo e gibbsita. Já para o estudo da humificação dos AHs extraídos das frações granulométricas, a quantificação do grau de humificação, do maior para o menor, é procedente da fração silte, seguidos da fração argila e, por fim, a fração areia. / The humification process, conversion of organic waste into humus, is an important factor to understand the organic matter dynamics. Its quantification is vital for the study of this substance chemical evolution. This study aimed at characterizing humic acid (HA) samples and quantify the degree of soil humification and physical fractions (particle size). The analysis of Spectroscopies of wavelenght dispersive X-ray fluorescence, visible fluorescence, vibrational infrared region, ultraviolet and visible light absorption and Raman along with the techniques of Thermal Analysis, scanning electron microscopy with field effect gun and dynamic light scattering were employed. The humification degree quantification revealed that the HA extracted from the 10-20cm depth presented more polycondensed structures. The HA fraction that presented the highest humification degree was extracted from the soil with the addition of liming, which demonstrates the limestone influence in the acceleration of the humification process. The study of the soil granulometric fractions determined, with infrared spectroscopy, the organic properties that are associated to soil fractions and that most of the minerals present in the granulometric fractions, were identified as kaolinite, halloysite, quartz and gibbsite.The study of the humification in the HA extracted from the granulometric fractions quantified the humification degree and revealed the highest values in the silt fraction followed by the clay fraction and, finally, the lowest values were found in the sand fraction.

Core- and Valence Photoelectron Spectroscopy (PES), X-ray- and Ultraviolet-Visible Absorption Spectroscopy (XAS and UV-Vis), Scanning Tunneling Microscopy (STM) and Density Functional Theory (DFT) calculations are used to study the electronic and geometrical structure of a class of macro-cyclic molecules, Phthalocyanines (Pc), on surfaces. These molecules are widely studied due to their application in many different fields. Multilayer and monolayer coverages of Iron Phthalocyanine (FePc) and metal-free Phthalocyanine (H2Pc) deposited on different surfaces are investigated in order to get insight in the electronic and geometrical structure of the obtained overlayers, of crucial importance for the understanding of the film functionality. Sublimation of molecular thick films on Si(100) and on conducting glass results in films with molecules mainly oriented with their molecular plane orthogonal to the surface. Ex-situ deposited H2Pc films on conductive glass show different molecular orientation and morphology with respect to the vacuum sublimated films. We study the monolayer adsorption structure of FePc and H2Pc and compare our results with other Pc’s adsorbed on graphite. We find that the molecular unit cell and the superstructure is characteristic for each Pc adsorbed on graphite, even if the geometrical size of the compared molecules is the same. The PE- and XA- spectra of FePc on graphite are essentially identical for the mono- and multilayer preparations, evidencing weak intermolecular and molecular-substrate interactions of van der Waals nature. Furthermore, we characterize Pc’s on InSb (001)-c(8x2). The substrate In rows are observed to be the adsorption site for Pc’s. We find that the growth of the two-dimensional islands of FePc is prolonged in the [-110] direction, in contrast to ZnPc adsorbed on the same substrate at room temperature. We interpret this result as an indication that the adsorption is controlled by the substrate corrugation observed at 70 K.

Organic molecules such as porphyrins and alkanethiols are currently being investigated for applications such as sensors, light-emitting diodes and single electron transistors. Porphyrins are stable, highly conjugated compounds and the choice of metal ion and substituents bound to the macrocycle as well as other effects such as chemical surrounding and cluster size modulate the electronic and photonic properties of the molecule. Porphyrins and their derivatives are relatively non-toxic and their very rich photo- and electro-chemistry, and small HOMO-LUMO gaps make them outstanding candidates for use in molecularly-enhanced electronic applications. For these studies, self-assembled tri-pyridyl porphyrin thiol derivatives have been fully characterized on Au(111) surfaces. A variety of surface characterization techniques such as Atomic Force Microscopy (AFM), Scanning Tunneling Microscopy (STM), FT-IR spectroscopy and X-ray photoelectron spectroscopy (XPS) have been implemented in order to obtain information regarding the attachment orientation based on the angle and physical height of the molecule, conductivity which is determined based on the apparent height and current-voltage (I-V) measurements of the molecule, conductance switching behavior due to conformational or other effects as well as the stability of the molecular ensembles. Specifically, the transport properties of free base and zinc coordinated tri-pyridyl porphyrin thiol molecular islands inserted into a dodecanethiol matrix on Au(111) were investigated using STM and cross-wire inelastic electron tunneling spectroscopy (IETS). The zinc porphyrin thiol islands observed by STM exhibited reversible bias induced switching at high surface coverage due to the formation of Coulomb islands of ca. 10 nm diameter driven by porphyrin aggregation. Low temperature measurements (~ 4 K) from crossed-wire junctions verified the appearance of a Coulomb staircase and blockade which was not observed for single molecules of this compound or for the analogous free base. Scanning probe lithography via nanografting has been implemented to directly assemble nanoscale patterns of zinc porphyrin thiols and 16-mercapotohexadecanoic acid on Au surfaces. Matrix effects during nanopatterning including solvent and background SAMs have been investigated and ultimately ~ 10 nm islands of zinc porphyrins have been fabricated which is the optimal size for the observed switching effect.