The ¹HNMR spectra of all possible structural isomers of mono and dihydroxy substituted naphthalenes are measured in trifluoracetic acid and trifluormethanesulfonic acid as well as in their deuterated derivatives. These spectra indicate different protonation/deuteration positions in the compounds studied. Whereas with the relative weak TFA the OH group as most basic group of the substrates is protonated, with the more acidic TFS also aromatic positions with lower basicity are protonated. However, some of these position were indicated only by using deutertated acids. To quantify the degree of proton/deuterium exchange at the aromatic rings, dioxane as proton standard was used. For the OH-protonation a complex between the appropriate naphthol and the acid used, in which a quick proton exchange can be occur, is assumed. Furthermore, the formation of corresponding trifluoroacetates or triflates by reaction of the naphthols with the corresponding acids has been indicated. In some cases, in which the ring positions of protonation are not definitely clear, 2D NOESYNMR experiments have been performed.

In analogy with the reaction of phenols with very strong super acids, these compounds can be protonated by the weaker super acid trifluoroacetic acid (TFA) and trifluoromethanesulphonic acid (TFS) also giving rise to the formation of OH and/or ring protonated products, which can be identified unambiguously by means of ¹HNMR spectroscopy. The same reactions are possible with the deuterated acids TFA-d and TFS-d. However, from these reactions, additional information on the proton and deuterium attack at different positions in the phenolic compounds is possible not detectable by the hitherto used non-deuterated acids. Moreover, the reaction of phenols with these deuterated acids allows the preparation of partially or fully deuterated phenols that are also important as markers in biological application and material chemistry.

Rhodopsin ist der Photorezeptor der Stäbchenzellen in der Retina von Vertebraten und wird als Prototyp für die gesamte Gruppe der GPCRs beforscht. Trifft ein Photon auf das Protein, so wird der über eine Schiffbase kovalent gebundene Chromophor von seiner 11-cis- in die All-trans-Konfiguration isomerisiert und setzt infolgedessen den Aktivierungsprozess in Gang. Dieser mündet in der aktiven Rezeptorkonformation, die das G-Protein Transducin aktivieren kann und dadurch eine Kaskade weiterer Aktivierungsschritten einleitet, die letztlich ein Nervensignal verursachen. Das Ziel dieser Arbeit war die Aufklärung der späten Aktivierungsschritte und ihrer Ursache-Wirkungs-Beziehungen. Zu diesem Zweck wurden Blitzlichtphotolyse, Elektronenspinresonanz (EPR) mit Spinlabeling (SDSL), UV/vis-Spektroskopie, FTIR-Spektroskopie und Fluoreszenzspektroskopie angewandt. Kinetische Messungen wurden unter identischen Bedingungen durchgeführt, um die Abfolge der mit den unterschiedlichen Techniken zugänglichen Aktivierungsschritte aufzuklären. Nach der Bildung des absorptionsspektroskopisch definierten Meta-II-Zustands bewegt sich die Helix TM6 in einem späteren Schritt als ganzes nach außen und markiert damit den Übergang von Meta-IIa zu Meta-IIb. Dadurch wird die bis dahin in der Membran verborgene D(E)RY-Region für das Umgebungsmedium zugänglich und nimmt ohne Zeitverzögerung ein Proton auf, wodurch der Meta-IIb*H+-Zustand gebildet wird. Die verfügbaren Daten sprechen dafür, dass das D(E)RY-Motiv bei der Aktivierung des Transducins sowohl die Alpha- als auch die Gamma-Untereinheit desselben bindet. Die Bindung von zu Transducin-Abschnitten analogen Peptiden kann dann erfolgen, wenn die Helix TM6 im nach außen bewegten Zustand ist, und führt zur Abgabe von bis zu zwei Protonen vom aktivierten Rhodopsin. Sowohl das D(E)RY- und das NPxxY(x)5,6F-Motiv als auch die beiden Zustände Meta-IIb und Meta-IIb*H+ könnten relevant für den sequenziellen Transducin-Aktivierungsmechanismus sein. / Rhodopsin is the photoreceptor in the rod cells of the vertebrate retina. It is considered as a prototype of the whole group of GPCRs. Upon absorption of a photon the chromophore, which is covalently bound through a Schiff base, is isomerized from its 11-cis into the all-trans configuration. This initiates the activation process and finally results in the active receptor conformation which is capable of activating the G protein transducin and thereby triggers a cascade of further activation steps which finally cause a nerve signal. The aim of this work was the clarification of the late activation steps and their cause-and-effect chain. For this purpose flash photolysis, electron paramagnetic resonance (EPR) with spin labeling (SDSL), UV/vis spectroscopy, FTIR spectroscopy and fluorescence spectroscopy were applied. Kinetic measurements were executed under identical conditions in order to elucidate the sequence of activation steps, which are accessible with the different techniques. After formation of the spectroscopically defined Meta-II state helix TM6 moves outward as a rigid body, thereby marking the transition from Meta-IIa to Meta-IIb. Therefore the D(E)RY region, which is until then buried in the membrane, gets accessible to the surrounding solution. It consequently takes up a proton without delay, thus forming the Meta-IIb*H+ state. Available data argue for the D(E)RY motif binding both the Alpha and the Gamma subunit of transducin during activation of the latter. The binding of peptides which are analogous to sections of transducin is possible when helix TM6 is in the outward position. It causes the release of up to two protons from the activated rhodopsin. Both the D(E)RY motif and the NPxxY(x)5,6F motif as well as both the states Meta-IIb and Meta-IIb*H+ are potentially relevant for the sequential transducin activation mechanism.

For every phenomenon found in inorganic materials, organic counterparts have been found in the last 50 years. The discovery of metallic conductivity in the inorganic conjugated polymer (SN)x was a forerunner to the discovery of metallic conductivity in Polyacetylene [1]. It was soon followed by the development of Polypyrrole and Polythiophene, and by the rediscovery of Polyaniline as a conducting polymer [2]. In polymers like Polyacetylene and Polythiophene, doping is by a redox reaction where the incorporation of electron withdrawing groups creates charge carriers in the polymer backbone. In contrast to these polymers, the main doping mechanism in Polyaniline is protonation, that is the attachment of a proton (donated by an acid) to specific sites (imine and amine groups) in the polymer. The protonated groups are also the sites where water and oxygen interact with the charge carriers on the polymer chain. A wide variety of quasi-particle states (excitons, bipolarons, separated polarons and polaron lattice forms) exist in Polyaniline, in its different states of oxidation and protonation. All of them have different transport and optical signatures. Out of these, only the polaron lattice gives rise to a half-filled conduction band, and therefore a metallic state [3]. This fascinating interplay of protonation and metallic features in Polyaniline, combined with its easy processibility, has made Polyaniline an attractive conducting polymer. Therefore the main focus of this thesis is on the role of the dopant on the electronic and optical properties of doped Polyaniline. The first chapter describes the main features of Polyaniline and its doping by protonation. The second chapter describes the experimental and simulation methods used in this thesis. Steady improvements in processing have led to reduced disorder in the samples, and have given rise to stronger metallic features like metallic (Drude-like) reflectivity in the infrared frequencies, and a positive temperature coefficient of the logarithmic derivative of the conductivity. High molecular weight Polyaniline doped with sulfonic acid dopants by surfactant-counterion processing, like Polyaniline doped with AMPSA (2-acrylamido-2-methyl-1-propanesulfonic acid) [4] and cast from dichloroacetic acid (DCA), shows all the metallic features indicative of an intrinsic metallic state [5]. In this thesis, the third chapter describes the spin-charge dynamics of Polyaniline doped with AMPSA (PANIAMPSA) through X-band Electron Spin Resonance studies [6]. Electron Spin Resonance (ESR) is an important technique to probe the spin-charge dynamics of conducting polymers [7, 8]. The X-band ESR spectra of PANI doped with AMPSA showed the presence of two lines (one broad and one narrow) at all temperatures and doping levels, indicative of two types of spin carriers. Three interesting features were observed in our study: a large linewidth ( ~100 Gauss), a maximum of ESR linewidth at ~ 25 K, and a surprising independence of linewidth on water/O2 . The temperature dependence of both linewidths suggests that the broad line is due to the delocalised charge carriers in well-ordered regions, and that the narrow line is due to localised spins in the disordered regions in the sample. Although the XRD spectra showed minimal crystallinity, the ESR and SQUID susceptibility had a strong Pauli contribution, indicative of an intrinsic metallic state. A similarity of the temperature dependence of linewidths of PANI-AMPSA with MWNT-s and HOPG graphite suggested that some quasi-2-D (Q2D) ordering is present in PANI-AMPSA. From Semi-empirical molecular modelling studies, a plausible hydrogen bonding pattern is suggested that can give rise to the Q2D graphene-like arrangement of the PANI polymer chains. This ordering is due to hydrogen bonding between the acrylamido group of the dopant and the amine fragment of the Polyaniline backbone. Hydrogen bonds are not just structural linkers between adjacent chains; they can have subtle effects on electronic states of the polymer backbone due to charge transfer/withdrawal by the hydrogen bond from the delocalised β-electron system of the backbone. The same Q2D model is used to explain the water/oxygen independence of linewidth in PANI-AMPSA. The temperature dependence of linewidth of both lines has been explained in terms of the QTDG (Quasi Two Dimensional Graphite) model, where a strong exchange interaction is presumed to arise between the 2D delocalised charge carriers and the localised spins, leading to a low-temperature peak in the the linewidth. Water is known to significantly enhance the conductive properties of doped Polyaniline [9]. A detailed DFT (Density Functional Theory) modelling study of the influence of water in doped Polyanilines is presented, which clearly indicated that water enhances the charge transfer between the counterion and the polymer backbone. The torsion angles between the adjacent phenyl rings of the emeraldine base decrease when the imine nitrogens are protonated by inorganic acids like HCl and HBr, and hydration of the acid counterions further decrease the torsion angles. In contrast, the torsion angles of the AMPSA protonated Polyaniline are already low (comparable to the hydrated cases), and the charge transferred by AMPSA is also enhanced. Visualisation of the molecular structure of the PANI-AMPSA complex suggested that water molecules may play a minimal role in the electronic properties of AMPSA doped Polyaniline. We suggest the Q2D ordering as the reason for the temperature dependence of the linewidth, the lack of oxygen and water dependence of the linewidth, as well as the enhanced metallic properties in PANI-AMPSA, as compared to other doped Polyanilines. The electronic states of Polyaniline are modified by both redox processes and protonation. This gives rise to a wide variety of optical states, which can be easily accessed by both applied potential and pH [10]. Therefore Polyaniline displays strong electrochromism across the visible, near-IR (NIR), IR and even microwave spectral regions. This feature has wide applications in electrochromic devices. However, a fundamental understanding of the phenomena behind this electrochromism, the charge carrier(s) responsible, and the relation of nanoscopic morphology and electrochemical properties to the electrochromism, is still not clear. In the fourth chapter, we have analysed extensive data from electrochromic devices [11]. Clear assignments are that certain population states contribute predominantly to certain spectral regions (e.g. bipolaron states to the IR, the valence band to the visible and other mid-gap states to the microwave). Among more specific findings, a prominent 7µm (0.16 eV) peak in MIR devices is ascribed to bipolarons, while a low-energy transition at 0.054 eV is ascribed to inter/intra-chain transitions. Each of these transitions is tracked with respect to changes in applied potential, as well as correlated with device morphology and construction. Our analysis of UV-Vis-MIR-FIR-microwave results along with detailed SEM data clearly relates performance in different wavelength regions to morphology. Preliminary kinetics analysis show that the diffusion rates in these devices could be improved further. These findings point to the potential design of very broad-band electrochromic systems encompassing the visible through microwave regions. Polyaniline in its insulating states can be considered as a series of linked oligoanilines. These oligoaniline states can either be considered as a model for describing the properties of the polymer, or can be interesting systems themselves in the light of single-molecular electronic devices [12]. Both applied potential and pH can change the electronic states of these systems. The ability of pH to modify the oxidation states in these systems (and induce electronic transport), and the influence of water on these properties can be a model for biological systems too. While a wealth of information on oligoanilines has been generated from experiments, computational modelling of these systems is less reported. Among many computational methods that have been developed for calculation of optical absorption spectra of molecules, Time Dependent Density Functional Theory (TDDFT) is the method with the widest use. TDDFT obtains the excitation energies of a molecule from the linear response of the electronic density to a external perturbing field [13]. Solvent effects, which are known to affect the excitation energies, are included through the SCRF/PCM (Self-consistent Reaction Field/ Polarizable Continuum Model). PCM is a method that treats the solvent molecules as a continuum, and self-consistently evaluates their electronic distribution around the solute. In the fifth chapter, a systematic study of the optical properties of neutral oligoaniline, in three oxidation states, is performed by varying the chain length and linearity of the backbone. The intrinsic accuracy in the excitation energies obtainable by the combined TDDFT/PCM formalism has enabled us to suggest effective oligomer lengths for the optical transitions in Polyaniline; these are 4 rings for emeraldine base, 4–8 rings for leucoemeraldine base and 4 rings for pernigraniline. The sensitivity of the 2.0 eV exciton peak in emeraldine base to the chemical environment is also apparent from this work. The Valence Density of States (VDOS) and vibrational frequencies, that have been obtained in course of these simulations, have been quantitatively analysed and are a useful addition to understanding the optical properties of neutral Polyanilines. A summary of the results of the dopant and water dependence on the electronic and structural properties of protonated oligoanilines was presented in the third chapter; the appendix describes the methodology in detail. It is worthwhile to emphasize that doped Polyaniline is a system where protonation, hydration and extended β-conjugation all occur together synergistically, and a good overall description of this system is necessary. Modelling the doped state of Polyaniline is a bit more difficult, due to spin polarisation. Ideally, conducting Polyaniline should be modelled in the solid state, with neighbouring chains, counterions and water molecules. Water is known to reversibly increase the macroscopic conductivity and ESR linewidth of doped Polyaniline. In the sixth chapter of this thesis, optical spectra of the bipolaron, separated polaron, and the polaron lattice forms of doped Polyaniline, explicitly including the counterions (Cl, Br, AMPSA) are obtained by the TDDFT method. All the polaronic lattice forms show a dominant absorption at 1.0–1.2 eV, with no absorptions in the range 1.4–2.0 eV. The inclusion of water molecules to solvate the counterions is shown to only weakly modify the optical properties in the polaron lattice form. In the case of polarons on a twisted chain, the 1.0 eV peak is shifted to 1.5 eV. For bipolarons, there is an absorption at 1.3–1.5 eV, along with another peak at 1.8 eV. Comparing with experimental spectra we suggest that the 1.5, 2.8 eV set belongs to a polaron lattice form wherein the chains are twisted. However, individually the 1.5 eV peak may equally come from bipolarons or separated polarons. The peak at 1.8 eV may either be ascribed to a bipolaron form (in which case there should be a 1.5 eV peak too), or to an isolated polaron. The isolated polaron may also show a peak at 2 eV and 3.5 eV that is clearly from a residual emeraldine base electronic state. The steady evolution of the (a) 2 eV exciton peak in emeraldine base to a (b) 1.6– 1.8 eV peak (isolated polarons) to a (c) 1.5 eV peak in the bipolaron form to (d) 1.3 eV peak in the separated polaron form to (e) a 1.0–1.2 eV peak in the fully doped metallic polaron lattice form is clear. This steady evolution observed from TDDFT simulations may help in clarifying the experimental assignments, especially in electrochemical studies on Polyaniline. Simulations including the water molecules were performed to study the experimentally observed dramatic changes on hydration in Polyaniline. However hydration of ions is a dynamic process and static geometries may not provide a fully realistic description. Combined ab initio Molecular Dynamics (AIMD) and TDDFT calculations may be necessary to realistically model the transport properties of doped Polyaniline. This chapter tries to lay a foundation for such work. The main results obtained in this thesis are summarized in the conclusion. To conclude, this thesis is on the electronic and optical properties of Polyaniline. An ESR study on AMPSA doped Polyaniline indicated a unique 2D nanoscopic morphology, and this structure was validated by molecular modelling. The detailed analyses on electrochromic devices led us to perform TDDFT simulations of neutral and doped Polyanilines. These simulations have resulted in clear UV-VIS-IR assignments in all forms of Polyaniline.

A Emodina (EMH) é uma das antraquinonas mais abundantes na natureza. Essa molécula vem sendo largamente usada como material de estudo científico por apresentar diversas atividades farmacológicas, tais como antiviral, antitumoral, antifungal, digestiva e outras. É conhecido que a Emodina em solução aquosa alcalina pode sofrer mais de um processo de desprotonação, apresentando-se na forma desprotonada, EM-, após a primeira desprotonação. Nesta tese de doutorado estudamos as propriedades estruturais e eletrônicas da molécula Emodina em meio solvente e em bicamadas lipídicas a fim de caracterizar as propriedades relacionadas à espectroscopia UV-Vis, à reatividade e à termodinâmica dessa molécula nesses ambientes. Realizamos cálculos quânticos com a Emodina em vácuo e em meio solvente, onde consideramos todos os possíveis sítios de desprotonação. Como resultados desses cálculos, identificamos os sítios da primeira, segunda e terceira desprotonação. Calculamos o pKa1 da Emodina em água e o pK*a1 em metanol através de simulações computacionais com o método Monte Carlo e cálculos quânticos, com o solvente descrito com o modelo contínuo polarizável. Nossos melhores valores para o pKa1 da Emodina determinados nesses solventes foram 8.4±0.5 e 10.3±1.5, que estão em boa concordância com os valores experimentais, (pKa1=8.0±0.2 e pK*a1=11.1±0.1) obtidos nesta tese para Emodina em água e metanol, respectivamente. Adicionalmente realizamos simulações com Dinâmica Molecular com as espécies EMH e EM- em bicamada lipídica de DMPC, para investigar a nível atômico as interações dessas espécies com a bicamada e determinar as posições preferenciais dessas espécies nesse ambiente anfifílico. Os resultados dessas simulações mostraram que as espécies EMH e EM- ficam inseridas na bicamada, na região polar dos lipídios, próximos aos gliceróis. Esses resultados corroboram as nossas medidas do espectro de absorção dessas espécies em bicamada lipídica, onde mostramos de forma qualitativa, que ambas as espécies ficam inseridas na bicamada, na região das cabeças polares dos lipídios. A análise das propriedades estruturais da bicamada na vizinhança das espécies da Emodina como área por lipídio e densidade eletrônica dos lipídios, mostrou que o efeito da EM- na estrutura da bicamada lipídica é maior do que o da EMH. Esses resultados corroboram as nossas medidas de DSC(Differential Scanning Calorimetry) das espécies da Emodina na bicamada. / Emodin (EMH) is one of the most abundant anthraquinone derivatives found in nature. This molecule has been used widely as research material, due to its biological and pharmacological activities such as antiviral, anticancer, antifungal, digestive and antibacterial activities. It is known that Emodin in alkaline aqueous solution can undergo more than one deprotonation, leading to the specie EM- in the first deprotonation process. In this PhD thesis, we studied the structural and electronic properties of this molecule in several solvents and lipid bilayers, in order to characterize the properties related to UV-Vis absorption spectroscopy, reactivity and thermodynamics of this molecule in these environments. Performing quantum mechanics (QM) calculations for all possible deprotonation sites and tautomeric isomers of Emodin in vacuum and in water, we identified the sites of the first, second and third deprotonations. We calculated the pKa1 of Emodin in water and pK*a1 in methanol with free energy perturbation method, implemented in the Monte Carlo simulation, and with QM calculations, where the solvent was treated as a polarizable continuum medium. Our best values for pKa1 of Emodin in these solvents were 8.4±0.5 and 10.3±1.5, which are in very good agreement with the experimental values obtained in this thesis pKa1=8.0±0.2 and pK*a1=11.1±0.1, for water and methanol, respectively. Additionally, we performed molecular dynamics simulations of both species in fully hydrated lipid bilayers of DMPC to investigate at atomic detail the molecular mechanism of the interaction of these species with lipid membrane and its preferred positions in this amphiphilic environment. As results of these simulations, we obtained that both species of Emodin have a strong tendency to insert into the lipid bilayer, remaining near the glycerol group of DMPC. These results corroborate our measured absorption spectra of these species in the bilayer, which qualitatively showed that both species are within the bilayer, inserted in the lipid headgroup region. Our results also show that the effect of EM- specie in the lipid bilayer structure is stronger than the EMH, which corroborate our DSC(Differential Scanning Calorimetry) measurements.

A Emodina (EMH) é uma das antraquinonas mais abundantes na natureza. Essa molécula vem sendo largamente usada como material de estudo científico por apresentar diversas atividades farmacológicas, tais como antiviral, antitumoral, antifungal, digestiva e outras. É conhecido que a Emodina em solução aquosa alcalina pode sofrer mais de um processo de desprotonação, apresentando-se na forma desprotonada, EM-, após a primeira desprotonação. Nesta tese de doutorado estudamos as propriedades estruturais e eletrônicas da molécula Emodina em meio solvente e em bicamadas lipídicas a fim de caracterizar as propriedades relacionadas à espectroscopia UV-Vis, à reatividade e à termodinâmica dessa molécula nesses ambientes. Realizamos cálculos quânticos com a Emodina em vácuo e em meio solvente, onde consideramos todos os possíveis sítios de desprotonação. Como resultados desses cálculos, identificamos os sítios da primeira, segunda e terceira desprotonação. Calculamos o pKa1 da Emodina em água e o pK*a1 em metanol através de simulações computacionais com o método Monte Carlo e cálculos quânticos, com o solvente descrito com o modelo contínuo polarizável. Nossos melhores valores para o pKa1 da Emodina determinados nesses solventes foram 8.4±0.5 e 10.3±1.5, que estão em boa concordância com os valores experimentais, (pKa1=8.0±0.2 e pK*a1=11.1±0.1) obtidos nesta tese para Emodina em água e metanol, respectivamente. Adicionalmente realizamos simulações com Dinâmica Molecular com as espécies EMH e EM- em bicamada lipídica de DMPC, para investigar a nível atômico as interações dessas espécies com a bicamada e determinar as posições preferenciais dessas espécies nesse ambiente anfifílico. Os resultados dessas simulações mostraram que as espécies EMH e EM- ficam inseridas na bicamada, na região polar dos lipídios, próximos aos gliceróis. Esses resultados corroboram as nossas medidas do espectro de absorção dessas espécies em bicamada lipídica, onde mostramos de forma qualitativa, que ambas as espécies ficam inseridas na bicamada, na região das cabeças polares dos lipídios. A análise das propriedades estruturais da bicamada na vizinhança das espécies da Emodina como área por lipídio e densidade eletrônica dos lipídios, mostrou que o efeito da EM- na estrutura da bicamada lipídica é maior do que o da EMH. Esses resultados corroboram as nossas medidas de DSC(Differential Scanning Calorimetry) das espécies da Emodina na bicamada. / Emodin (EMH) is one of the most abundant anthraquinone derivatives found in nature. This molecule has been used widely as research material, due to its biological and pharmacological activities such as antiviral, anticancer, antifungal, digestive and antibacterial activities. It is known that Emodin in alkaline aqueous solution can undergo more than one deprotonation, leading to the specie EM- in the first deprotonation process. In this PhD thesis, we studied the structural and electronic properties of this molecule in several solvents and lipid bilayers, in order to characterize the properties related to UV-Vis absorption spectroscopy, reactivity and thermodynamics of this molecule in these environments. Performing quantum mechanics (QM) calculations for all possible deprotonation sites and tautomeric isomers of Emodin in vacuum and in water, we identified the sites of the first, second and third deprotonations. We calculated the pKa1 of Emodin in water and pK*a1 in methanol with free energy perturbation method, implemented in the Monte Carlo simulation, and with QM calculations, where the solvent was treated as a polarizable continuum medium. Our best values for pKa1 of Emodin in these solvents were 8.4±0.5 and 10.3±1.5, which are in very good agreement with the experimental values obtained in this thesis pKa1=8.0±0.2 and pK*a1=11.1±0.1, for water and methanol, respectively. Additionally, we performed molecular dynamics simulations of both species in fully hydrated lipid bilayers of DMPC to investigate at atomic detail the molecular mechanism of the interaction of these species with lipid membrane and its preferred positions in this amphiphilic environment. As results of these simulations, we obtained that both species of Emodin have a strong tendency to insert into the lipid bilayer, remaining near the glycerol group of DMPC. These results corroborate our measured absorption spectra of these species in the bilayer, which qualitatively showed that both species are within the bilayer, inserted in the lipid headgroup region. Our results also show that the effect of EM- specie in the lipid bilayer structure is stronger than the EMH, which corroborate our DSC(Differential Scanning Calorimetry) measurements.

Ziel der Untersuchungen war die Charakterisierung der Protonierungs-, Komplexbildungs- und Verteilungseigenschaften von tripodalen Azaliganden unter Anwendung thermodynamischer und spektroskopischer Verfahren. Im Vordergrund stand dabei der Einfluß des Lösungsmittels auf die zugrundeliegenden Gleichgewichte. Ausgehend von dem Aminopodanden Tris(2-aminoethylamin) (tren) wurden für eine Reihe abgeleiteter Verbindungen mit unterschiedlichen Stickstoffdonorfunktionen und Substituenten Faktoren untersucht, welche die beteiligten Gleichgewichte beeinflussen. Das Protonierungsverhalten der Polyaminverbindungen ist im starken Maße von elektrostatischen, elektronischen und Solvenseinflüssen abhängig, welche durch den Abstand der benachbarten Aminfunktionen, die Substitution am Aminstickstoffatom und die sterischen Eigenschaften der Substituenten bestimmt werden. Faktoren, welche die Solvatation der Aminfunktionen verringern, führen zu einer Verringerung der Protonierungskonstanten. Zudem beeinflussen die Zusammensetzung der verwendeten Methanol-Wasser-Gemische sowie das verwendete Leitsalz die Protonierungskonstanten z.T. deutlich. Die Komplexbildung der untersuchten Azapodanden mit Ag+ in Methanol zeigt Unterschiede, welche hauptsächlich auf die unterschiedliche Basizität von Imin- bzw. Aminstickstoffatomen sowie Substituenteneffekte zurückzuführen sind. Von sterisch aufwendigen Substituenten an den Donorfunktionen der Podandarme können zudem destabilisiernde Effekte infolge der Beeinflussung der Koordinationsgeometrie von Ag+ ausgehen. Heteroditope Tetraazacryptanden zeigen gegenüber abgeleiteten offenkettigen Podanden erhöhte Stabilitätskonstanten, wobei auch die Verknüpfungsposition der tripodalen Einheiten am Phenylspacer und die Bindung von Wasser im Käfighohlraum eine Rolle spielen. Lösungsmittelpolarität und Gegenion haben einen deutlichen Einfluß auf die Komplexbildung mit Ag+. Der Schwerpunkt von Untersuchungen an Zweiphasensystemenen wäßrig-organisch lag auf dem Übergang von Wasser in die organische Phase unter dem Einfluß von extrahierten Spezies bei der Kationen- und Anionenextraktion. Mit der Verteilung von Liganden und Kationen- bzw. Anionenkomplexen lassen sich Änderungen des Wassersättigungsgehaltes in der niedrigpolaren organischen Phase registrieren, die mit der unterschiedlichen Hydratation der Spezies korrelieren. Qualitativ wurde die Hydratation von Azapodanden mittels IR- und 1H-NMR-Spektroskopie nachgewiesen, wobei auch Hinweise auf bestimmte, die Hydratation verringernde Faktoren, wie intramolekulare Wasserstoffbrücken, erhalten wurden. Quantitativ konnten mittels Karl-Fischer-Titration und Verteilungsmessungen Hydratationszahlen für ausgewählte Ligansysteme bestimmt werden. Extrahierte Komplexe der Verbindungen mit Ag+, Co2+, Ni2+ und Zn2+ zeigen eine gegenüber den freien Komplexbildnern veränderte Hydratation. Bei Ag+ kann in allen Fällen von einer deutlichen Verringerung der Hydratationszahlen ausgegangen werden. Für die zweifachgeladenen Kationen konnte kein klarer Nachweis erbracht werden. Es ergeben sich aber Hinweise, wonach zum Teil keine Verringerung auftritt, was auf eine zusätzliche Koordinationsstellen von Wasser am Kation hinweist. Bei der Iodidextraktion treten bei gleichzeitiger pH-Abhängigkeit mehrere Komplexspezies auf, was die Bestimmung von Hydratationszahlen erschwert. Als hilfreich erwies sich die Simulation für verschiedene mögliche Zusammensetzungen. Dabei stellte sich heraus, daß der 1:1-Komplex des untersuchten monoprotonierten Aminopodanden in Chloroform wahrscheinlich stärker hydratisiert ist als der freie Ligand, während die entsprechende 1:2-Spezies (Ligand:Iodid) eine ähnliche oder schwächere Hydratation aufweist als der Ligand.

Ziel der Untersuchungen war die Charakterisierung der Protonierungs-, Komplexbildungs- und Verteilungseigenschaften von tripodalen Azaliganden unter Anwendung thermodynamischer und spektroskopischer Verfahren. Im Vordergrund stand dabei der Einfluß des Lösungsmittels auf die zugrundeliegenden Gleichgewichte. Ausgehend von dem Aminopodanden Tris(2-aminoethylamin) (tren) wurden für eine Reihe abgeleiteter Verbindungen mit unterschiedlichen Stickstoffdonorfunktionen und Substituenten Faktoren untersucht, welche die beteiligten Gleichgewichte beeinflussen. Das Protonierungsverhalten der Polyaminverbindungen ist im starken Maße von elektrostatischen, elektronischen und Solvenseinflüssen abhängig, welche durch den Abstand der benachbarten Aminfunktionen, die Substitution am Aminstickstoffatom und die sterischen Eigenschaften der Substituenten bestimmt werden. Faktoren, welche die Solvatation der Aminfunktionen verringern, führen zu einer Verringerung der Protonierungskonstanten. Zudem beeinflussen die Zusammensetzung der verwendeten Methanol-Wasser-Gemische sowie das verwendete Leitsalz die Protonierungskonstanten z.T. deutlich. Die Komplexbildung der untersuchten Azapodanden mit Ag+ in Methanol zeigt Unterschiede, welche hauptsächlich auf die unterschiedliche Basizität von Imin- bzw. Aminstickstoffatomen sowie Substituenteneffekte zurückzuführen sind. Von sterisch aufwendigen Substituenten an den Donorfunktionen der Podandarme können zudem destabilisiernde Effekte infolge der Beeinflussung der Koordinationsgeometrie von Ag+ ausgehen. Heteroditope Tetraazacryptanden zeigen gegenüber abgeleiteten offenkettigen Podanden erhöhte Stabilitätskonstanten, wobei auch die Verknüpfungsposition der tripodalen Einheiten am Phenylspacer und die Bindung von Wasser im Käfighohlraum eine Rolle spielen. Lösungsmittelpolarität und Gegenion haben einen deutlichen Einfluß auf die Komplexbildung mit Ag+. Der Schwerpunkt von Untersuchungen an Zweiphasensystemenen wäßrig-organisch lag auf dem Übergang von Wasser in die organische Phase unter dem Einfluß von extrahierten Spezies bei der Kationen- und Anionenextraktion. Mit der Verteilung von Liganden und Kationen- bzw. Anionenkomplexen lassen sich Änderungen des Wassersättigungsgehaltes in der niedrigpolaren organischen Phase registrieren, die mit der unterschiedlichen Hydratation der Spezies korrelieren. Qualitativ wurde die Hydratation von Azapodanden mittels IR- und 1H-NMR-Spektroskopie nachgewiesen, wobei auch Hinweise auf bestimmte, die Hydratation verringernde Faktoren, wie intramolekulare Wasserstoffbrücken, erhalten wurden. Quantitativ konnten mittels Karl-Fischer-Titration und Verteilungsmessungen Hydratationszahlen für ausgewählte Ligansysteme bestimmt werden. Extrahierte Komplexe der Verbindungen mit Ag+, Co2+, Ni2+ und Zn2+ zeigen eine gegenüber den freien Komplexbildnern veränderte Hydratation. Bei Ag+ kann in allen Fällen von einer deutlichen Verringerung der Hydratationszahlen ausgegangen werden. Für die zweifachgeladenen Kationen konnte kein klarer Nachweis erbracht werden. Es ergeben sich aber Hinweise, wonach zum Teil keine Verringerung auftritt, was auf eine zusätzliche Koordinationsstellen von Wasser am Kation hinweist. Bei der Iodidextraktion treten bei gleichzeitiger pH-Abhängigkeit mehrere Komplexspezies auf, was die Bestimmung von Hydratationszahlen erschwert. Als hilfreich erwies sich die Simulation für verschiedene mögliche Zusammensetzungen. Dabei stellte sich heraus, daß der 1:1-Komplex des untersuchten monoprotonierten Aminopodanden in Chloroform wahrscheinlich stärker hydratisiert ist als der freie Ligand, während die entsprechende 1:2-Spezies (Ligand:Iodid) eine ähnliche oder schwächere Hydratation aufweist als der Ligand.