Hannover, Universiẗat, Diss., 1999.

Berlin, Freie Universiẗat, Diss., 2001. / Dateiformat:zip, Dateien im PDF-Format.

Dresden, TU Dresden, Diss., 2005. / Text engl. Computerdatei im Fernzugriff.

Würzburg, Univ., Diss., 2008

Universiẗat, Diss., 2001--Mainz.

Univ., Diss.--Regensburg, 1999.

TU Dresden, Diss., 2005--Dresden. / Text engl.

For grafting polypyrrole on oxidized surfaces, 3-substituted pyrrole alkyl phosphonic acids, 11-(pyrrol-3-yl undecyl) trimethoxysilanes and 1-substituted pyrrole alkyl organosilanes with different chain length were designed and successfully synthesized as adhesion promoters. These new derivatives were studied for their adsorption behavior on oxide substrates and chemical or electrochemical deposition of polypyrrole over modified oxide surface or electrodes. Several analytical techniques such as contact angle measurement, surface plasmon resonance spectroscopy (SPR), UV-VIS Spectroscopy, grazing incident FTIR, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and atomic force microscopy (AFM) were employed to characterize the adsorbed layers on different substrates. Contact angle measurement and ellipsometry data showed that high concentrations in apolar hydrocarbon solvent and long reaction times are sufficient to form tightly packed monolayer of 1-substituted pyrrole alkyl monochlorosilanes (PMCS) on substrates. Adsorption kinetics were studied by SPR and showed that the adsorption took place within a few seconds, then continuously increased and reached a plateau. The orientation of these synthesized monomers is investigated to be well-suited for use as adhesion promoter. CV-measurements showed that 3-substrated pyrrole derivatives had lower oxidation potential, whereas 1-substituted pyrrole derivatives had higher oxidation potential compared with pyrrole. Surface deposition of polypyrrole on the adhesion promoter modified (silane-modified and phosphonic acid-modified) substrates by chemical and electrochemical polymerization were investigated. PPy films formed on the modified surfaces by surface chemical polymerization showed a better adhesion compared to those on the unmodified surfaces. The morphology of PPy films was influenced by the alkyl chain length of the adhesion promoter and the deposition condition, such as choice of oxidant and solvent. The thickness of the resulting PPy films were controlled by the polymerization conditions, such as choice of solvent, deposition time, pyrrole to oxidant ratio and monomer concentration. The thickness of the deposited PPy film was estimated in the range of 10-400 nm by AFM and ellipsometry. The electrical properties were studied by current-voltage (j-V) measurement. Temperature dependence of j-V characteristics of Si/SiO2/PPy/PMCS-16/Al films revealed that the current increases with temperature, the film shows a typical semiconductor behavior. The use of these adhesion promoters modified electrode for electrochemical polymerization resulted in adhesive polypyrrole films.Also the 3-substituted pyrrole phosphonic acids were found to be homo-and co-polymerizable (with pyrrole) under chemical methods. TGA showed that homopolymers are less stable than polypyrrole due to the 3-substitution. he homopolymer of 3-substituted phosphonic acid derivatives of pyrrole is soluble. Films coated from the MeOH solution of homopolymer could be successfully used as humidity sensors. It is observed that the resistivity of the 3-substituted homopolypyrrole sensors increases and capacitance decreases during exposure to humid air. The polypyrrole films obtained by surface chemical polymerization was also used as humidity sensors.

For grafting polypyrrole on oxidized surfaces, 3-substituted pyrrole alkyl phosphonic acids, 11-(pyrrol-3-yl undecyl) trimethoxysilanes and 1-substituted pyrrole alkyl organosilanes with different chain length were designed and successfully synthesized as adhesion promoters. These new derivatives were studied for their adsorption behavior on oxide substrates and chemical or electrochemical deposition of polypyrrole over modified oxide surface or electrodes. Several analytical techniques such as contact angle measurement, surface plasmon resonance spectroscopy (SPR), UV-VIS Spectroscopy, grazing incident FTIR, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and atomic force microscopy (AFM) were employed to characterize the adsorbed layers on different substrates. Contact angle measurement and ellipsometry data showed that high concentrations in apolar hydrocarbon solvent and long reaction times are sufficient to form tightly packed monolayer of 1-substituted pyrrole alkyl monochlorosilanes (PMCS) on substrates. Adsorption kinetics were studied by SPR and showed that the adsorption took place within a few seconds, then continuously increased and reached a plateau. The orientation of these synthesized monomers is investigated to be well-suited for use as adhesion promoter. CV-measurements showed that 3-substrated pyrrole derivatives had lower oxidation potential, whereas 1-substituted pyrrole derivatives had higher oxidation potential compared with pyrrole. Surface deposition of polypyrrole on the adhesion promoter modified (silane-modified and phosphonic acid-modified) substrates by chemical and electrochemical polymerization were investigated. PPy films formed on the modified surfaces by surface chemical polymerization showed a better adhesion compared to those on the unmodified surfaces. The morphology of PPy films was influenced by the alkyl chain length of the adhesion promoter and the deposition condition, such as choice of oxidant and solvent. The thickness of the resulting PPy films were controlled by the polymerization conditions, such as choice of solvent, deposition time, pyrrole to oxidant ratio and monomer concentration. The thickness of the deposited PPy film was estimated in the range of 10-400 nm by AFM and ellipsometry. The electrical properties were studied by current-voltage (j-V) measurement. Temperature dependence of j-V characteristics of Si/SiO2/PPy/PMCS-16/Al films revealed that the current increases with temperature, the film shows a typical semiconductor behavior. The use of these adhesion promoters modified electrode for electrochemical polymerization resulted in adhesive polypyrrole films.Also the 3-substituted pyrrole phosphonic acids were found to be homo-and co-polymerizable (with pyrrole) under chemical methods. TGA showed that homopolymers are less stable than polypyrrole due to the 3-substitution. he homopolymer of 3-substituted phosphonic acid derivatives of pyrrole is soluble. Films coated from the MeOH solution of homopolymer could be successfully used as humidity sensors. It is observed that the resistivity of the 3-substituted homopolypyrrole sensors increases and capacitance decreases during exposure to humid air. The polypyrrole films obtained by surface chemical polymerization was also used as humidity sensors.

Im Rahmen dieser Arbeit wurde ein synthetischer Membrantransporter für acetylierte Aminosäurecarboxylate entworfen und hergestellt. Als Bindungsstelle für die Carboxylate wurde das Guanidiniocarbonylpyrrol-Motiv von Schmuck verwendet. In den Seitenarm des Pyrrols wurde ein L-Valinamid-Rest eingebracht, um die Möglichkeit zu zusätzlichen Wasserstoffbrückenbindungen zu bieten und gegebenenfalls Substrat- und Enantioselektivität zu erreichen. Zur Herstellung der Löslichkeit in unpolaren Medien wie dem Inneren der Zellmembran musste eine lipophile Gruppe eingebracht werden. Als löslichkeitsvermittelnder Rest wurde Tris-(Dodecyloxy)phenylmethylen ausgewählt, das drei lange unpolare Alkylreste trägt. Zusammengenommen ergab sich so ein Rezeptor für Oxo-Anionen und speziell für Aminosäurecarboxylate mit erhöhter Löslichkeit in organischen Medien. Somit war die Fähigkeit zu Membrantransport gegeben. In Kraftfeldrechnungen erhielt man die vermutliche Struktur des Rezeptor-Substrat-Komplexes, der eine Kombination aus einer Salzbrücke, Wasserstoffbrückenbindungen und einer Stapelwechselwirkung von Guanidinum-Kation, Benzylgruppe und ggf. aromatischem Rest des Aminosäuresubstrates aufweist. Nach erfolgreicher Synthese wurde in Extraktionsexperimenten die Fähigkeit des Rezeptors erprobt, Aminosäurecarboxylate aus einer wässrigen in eine organische Phase aus zu überführen. Man erhielt das beste Extraktionsvermögen für Ac-Trp-OH, gefolgt von Ac Phe OH und Ac Tyr OH. Es wurde eine neue Formel aufgestellt, mit der aus den pKS-Werten der Substrate und den Extraktionsdaten mit und ohne Rezeptor die Bindungskonstanten der Rezeptor-Substrat-Komplexe berechnet werden konnten. Die Größe der Bindungkonstanten entsprach der Reihenfolge Trp > Tyr > Phe ~ Val mit den höchsten Bindungskonstanten für das Tryptophanderivat mit 1.5*10E4 1/M. Zur Bestätigung der Bindungskonstanten wurden ITC-Messungen durchgeführt. Es wurden Messungen des Rezeptors in Chloroform mit den tert-Butylammoniumsalzen der acetylierten Aminosäuren Phenylalanin, Tyrosin und Valin durchgeführt. Für die Werte von Enthalpie und Entropie konnten bei dieser Auswertung konsistente Werte ermittelt werden. Die höchsten Werte der Enthalpie erhielt man für das Tyrosinderivat mit 3.7*10E3 cal/mol, gefolgt vom Phenylalaninderivat mit 2.8*10E3 cal/mol und Valinderivat mit 1.3*10E3 cal/mol. Diese Abstufung entspricht dem Einfluss des aromatischen Restes, der durch die Stapelwechselwirkung mit dem Guanidinium-Kation die Bindungswärme erhöht und durch den damit verbundenen engeren Komplex den Wert für die Entropie senkt. Für die Evaluierung des Transportvermögens wurden U-Rohr-Versuche verschiedener Art durchgeführt. Es wurde ein Gradient von pH 6 in der Ausgangsphase auf pH 8 in der Zielphase eingesetzt, wodurch der Rezeptor an der Grenzfläche zur Zielphase deprotoniert wurde, was zu gerichtetetem Transport führte. Es ergaben sich recht starke Unterschiede für die Fluxwerte der einzelnen Substraten, die der Reihenfolge Val > Phe > Ala > Trp > Tyr folgten. Dabei wurde das Valinderivat um den Faktor 17 schneller als das Tyrosinderivat befördert, mit dem recht hohen Flux von 1.11*10E-6 mol/m2*s, was nahe an den höchsten literaturbekannten Wert für acetylierte Aminosäuren heranreicht. Durch Verwendung gleicher Substratkonzentrationen in Start- und Zielphase konnte aktiver Transport nachgewiesen werden, d.h. Transport gegen das Konzentrationsgefälle. Die Triebkraft des Transportes war der Gradient von pH 6 auf pH 8 zwischen Ausgangs- und Zielphase, der durch den Symport von Substrat und einem Proton ausgeglichen wurde. Bei einem kompetitiven Versuch mit einer Mischung der verschiedenen Substrate in der Ausgangsphase wurden veränderte Fluxwerte und Selektivitäten festgestellt. Die neue Reihenfolge der Transportgeschwindigkeit war nun Trp > Phe > Val > Tyr > Ala, wobei die Fluxwerte fast durchgehend niedriger waren als im Einzelversuch. Die Veränderung der Werte erschließt sich bei Vergleich mit den thermodynamischen Daten aus den Extraktionsexperimenten. Bei direkter Konkurrenz um den Rezeptor wurden diejenigen Substrate mit den höchsten Bindungskonstanten bevorzugt, unabhängig von ihrer Transportgeschwindigkeit. Die schwächer bindenden Substrate wurden aus dem Komplex verdrängt und wiesen deswegen niedrigere Transportwerte auf. Der kompetitive Versuch ist somit eine stärkere Abbildung der Bindungsstärke und entspricht eher der Situation in einer realen Zelle. / Within the scope of this work a new membrane carrier for acetylated amino acids was designed and synthesized. For the binding site of the carboxylate the guanidinio-carbonylpyrrole motif by Schmuck was selected. In the pyrrole’s side chain an L-valinamide residue was introduced, to allow for additional hydrogen bonding and potentially achieve substrate- and enantioselectivity. For solubility in nonpolar media such as the inner part of the cell membrane a lipophilic group had to be introduced. Tris-(dodecyloxy)-phenylmethylene, which bears three long, nonpolar alkyl chains, was selected to procure the desired solubility. All in all this yielded a receptor for oxo-anions and especially for amino acid carboxylates with increased solubility in organic media. This design resulted in the ability for membrane transport. In force field calculations the probable structure of the receptor-substrate-complex was obtained. It showed a combination of a salt bridge, hydrogen bonds and pi-stacking between the guanidinium cation, the benzyl group and, if applicable, the amino acid’s aromatic residue. After the successful synthesis, extraction experiments were carried out to test the receptor’s ability to transfer amino acid carboxylates from an aqueous into an organic phase. The best extractability was attained for Ac-Trp-OH, followed by Ac-Phe-OH and Ac-Tyr-OH. A new equation was established to calculate the binding constants of the receptor-substrate-complexes with the known pKS-values of the substrates and the extraction data with and without receptor. The values of the binding constants followed the order Trp > Tyr > Phe ~ Val with the highest values for the tryptophane derivative with 1.5*10E4 1/M. To confirm the binding constants, ITC experiments were conducted. Measurements of the receptor in chloroform with the tert-butylammonium salts of the acetylated amino acids phenylalanine, tyrosine and valine were conducted.For the enthalpy and entropy consistent values could be determined. These were 3.7*10E3 cal/mol for the tyrosine derivative, 2.8*10E3 cal/mol for the phenylalanine derivative and 1.3*10E3 cal/mol for the valine derivative. This incrementation complies with the influence of the aromatic residue, which increases the binding heat by the pi-stacking and decreases the value of the entropy because of the resulting tighter complex. For the evaluation of the transport capabilities various U-tube experiments were conducted. A gradient from pH 6 in the source phase to pH 8 in the target phase was employed, which led to deprotonation of the receptor near the interface to the target phase, resulting in directed transport. There were quite strong differences for the substrates’ flux values, which followed the order of Val > Phe > Ala > Trp > Tyr. The valine derivative was transported 17 times faster than the tyrosine derivative, with a quite high flux of 1.11*10E-6 mol/m2*s. This is close to the highest literature-known value for acetylated amino acids. By employing analogous substrate concentrations in the source and target phase, active transport, that is transport against the concentration gradient, could be achieved. The driving force of the transport was the gradient from pH 6 to pH 8 between the source and target phase, which was diminished by the symport of substrate and a proton. In a competitive experiment with a mixture of the various substrates in the source phase different values for flux and selectivity were found. The new order of the transport velocities was now Trp > Phe > Val > Tyr > Ala. Nearly all of the flux values were lower than before. The change of the values can be explained by the comparison with the thermodynamic data from the extraction experiments. With direct competition for the receptor, the substrates with higher binding constants were preferred, independent of their transport velocity. The substrates with weaker binding were expulsed from the complex and now showed lower transport values. The competitive transport experiment is therefor a better depiction of the binding strength and comes closer to the situation in a real cell.