Squaraine mit ausgedehnter Konjugation

Squaraine mit ausgedehnter Konjugation: Die vorliegende Arbeit ist in zwei Teilbereiche gegliedert, wobei der erste Teil die Synthese und Eigenschaftsuntersuchung symmetrischer und unsymmetrischer, stilbenoider Squaraine mit ausgedehnter Konjugation (DAD-Systeme) betrifft. Im zweiten Teil der Arbeit werden als Modellverbindungen für diese Squaraine Oligo(phenylenvinylen)e (OPVs) mit terminaler Donor-Acceptor-Substitution hergestellt.Es wurden drei unterschiedliche Klassen von konjugationsverlängerten Squarainen synthetisiert: unsymmetrische und symmetrische Monosquaraine sowie Oligosquaraine mit zwei, drei oder vier quarylium-Einheiten. Um eine bessere Löslichkeit zu gewährleisten, tragen die meisten Verbindungen voluminöse, flexible Bis(2-hexyloctyl)amino-Reste. Teilweise konnte die Löslichkeit auch durch zusätzliche Hexylseitenketten noch weiter verbessert werden. Der Aufbau der stilbenoiden Resorcine, die zur Synthese der entsprechenden Squaraine benötigt werden, erfolgte fast ausschließlich über die Wittig-Horner-Reaktion. Die 3,5-Dihydroxysubstitution erhöht die Nucleophilie in der 4-Position, so daß sich die stilbenoiden Resorcine in guten Ausbeuten mit Quadratsäure oder mit einer Semiquadratsäure zu den gewünschten Squarainen kondensieren ließen. Die Herstellung der Donor-Acceptor-substituierten OPVs erfolgte nach einer konvergenten Synthesestrategie, bei der auf eine repetitive Wittig-Horner-Reaktion und eine einfache Schutzgruppentechnik zurückgegriffen wurde. Als Acceptorgruppen dienten Formyl-, Cyano- und Nitrosubstituenten, als Donorgruppe wurden Bis(2-Hexyloctyl)amino-Reste eingesetzt. Die igenschaftsuntersuchungen an den konjugierten Oligomeren konnten zur Aufklärung des ungewöhnlichen spektroskopischen Verhaltens der Squaraine beitragen. Es wurde ein athematischer Ansatz entwickelt, der das Absorptionsverhalten D-A-substituierter Oligo(phenylenvinylen)e exakt beschreiben kann. Semiempirische Rechnungen und elektrooptische bsorptionsmessungen an diesen Verbindungen bestätigten die experimentell gefundenen Trends.

From discrete anions to extended solids: new uranium thiophosphates

Die wichtigste Klasse zeotyper Verbindungen sind die Thio- und Selenophosphate der Übergangsmetalle. Ziel dieser Dissertation war die Darstellung und Charakterisierung neuer Uranthiophosphate. Die dargestellten Verbindungen enthalten vierwertige Urankationen, die von acht Schwefelatomen koordiniert sind. Da die enthaltenen Thiophosphatanionen in den meisten Fällen als zweizähnige Liganden fungieren, entstehen dreidimensionale Netzwerke mit pseudotetraedrisch koordinierten Metallzentren. In der Verbindung U(P2S6)2 durchdringen sich drei identische diamantartige Netzwerke, wodurch optimale Raumerfüllung erreicht wird. Die Einführung von Alkalimetallkationen in das System führt zu einer Vielzahl neuer Verbindungen, deren Eigenschaften durch die Stöchiometrie der Edukte und durch die Kationenradien bestimmt werden. Beispielsweise enthält die Kristallstruktur von Na2U(PS4)2 zweidimensionale anionische [U(PS4)2]n-Schichten, während die analoge Verbindung CsLiU(PS4)2 eine poröse dreidimensionale Netzwerkstruktur besitzt. Der Vergleich der untersuchten quaternären und quinären Verbindungen zeigt, dass eine Korrelation zwischen dem Kationenradius und dem Durchmesser der Poren besteht. Dies lässt auf eine Templatfunktion der Alkalimetallkationen beim Aufbau der anionischen Teilstruktur schließen. Die neuen Verbindungen wurden aus reaktiven Polysulfidschmelzflüssen oder durch Auflösen amorpher Vorläufer in Alkalimetallchloridschmelzen synthetisiert. Die Kristallstrukturen wurden durch Einkristall-Röntgenmethoden bestimmt. Ein Vergleich der magnetischen Eigenschaften der Verbindungen beweist, dass in allen untersuchten Fällen U(IV) vorliegt. Die Substanzen zeigen paramagnetisches Verhalten, in UP2S7 und CsLiU(PS4)2 sind außerdem antiferromagnetische Wechselwirkungen zwischen benachbarten Uranatomen nachweisbar.

Polyelectrolytes and their counterions studied by EPR spectroscopy

In this thesis methods of EPR spectroscopy were used to investigate polyion-counterion interactions in polyelectrolyte solutions. The fact that EPR techniques are local methods is exploited and by employing spin-carrying (i.e., EPR-active) probe ions it is possible to examine polyelectrolytes from the counterions’ point of view. It was possible to gain insight into i) the dynamics and local geometry of counterion attachment, ii) conformations and dynamics of local segments of the polyion in an indirect manner, and iii) the spatial distribution of spin probe ions that surround polyions in solution. Analysis of CW EPR spectra of dianion nitroxide spin probe Fremy’s salt (FS, potassium nitrosodisulfonate) in solutions of cationic PDADMAC polyelectrolyte revealed that FS ions and PDADMAC form transient ion pairs with a lifetime of less than 1 ns. This effect was termed as dynamic electrostatic attachment (DEA). By spectral simulation taking into account the rotational dynamics as a uniaxial Brownian reorientation, also the geometry of the attached state could be characterized. By variation of solvent, the effect of solvent viscosity and permittivity were investigated and indirect information of the polyelectrolyte chain motion was obtained. Furthermore, analysis of CW EPR data also indicates that in mixtures of organic solvent/water PDADMAC chains are preferentially solvated by the organic solvent molecules, while in purely aqueous mixtures the PDADMAC chain segments were found in different conformations depending on the concentration ratio R of FS counterions to PDADMAC repeat units.Broadenings in CW EPR spectra of FS ions were assigned to spin-exchange interaction and hence contain information on the local concentrations and distributions of the counterions. From analysis of these broadenings in terms of a modified cylindrical cell approach of polyelectrolyte theory, radial distribution functions for the FS ions in the different solvents were obtained. This approach breaks down in water above a threshold value of R, which again indicates that PDADMAC chain conformations are altered as a function of R. Double electron-electron resonance (DEER) measurements of FS ions were carried out to probe the distribution of attached counterions along polyelectrolyte chains. For a significant fraction of FS spin probes in solution with a rigid-rod model polyelectrolyte containing charged Ru2+-centers, a bimodal distance distribution was found that nicely reproduced the spacings of direct and next-neighbor Ru2+-centers along the polyelectrolyte: 2.35 and 4.7 nm. For the system of FS/PDADMAC, DEER data could be simulated by assuming a two-state distribution of spin probes, one state corresponding to a homogeneous (3-dimensional) distribution of spin probes in the polyelectrolyte bulk and the other to a linear (1-dimensional) distribution of spin probes that are electrostatically condensed along locally extended PDADMAC chain segments. From this analysis it is suggested that the PDADMAC chains form locally elongated structures of a size of at least ~5 nm.

Rod-coil copolymer structures

Skalenargumente werden verwendet, um Rod-Coil Copolymere mit fester Zusammensetzung von steifen Stäbchen und flexiblen Ketten zu studieren. In einem selektiven Lösungsmittel, in dem sich nur die Ketten lösen, bildet ein Rod-Coil Multiblock zylinderförmige Micellen aus aggregierten Stäbchen verbunden durch Kettenstücke. Die Stäbchen aggregieren, um Energie zu gewinnen. Dieser Prozeß wird durch den Entropieverlust der flexiblen Ketten ausgeglichen. Das Adsorptionsverhalten von Aggregaten aus parallel aneinandergelagerten, einzelnen Rod-Coil Diblöcken in selektivem Lösungsmittel wird anhand von erweiterten Skalenbetrachtungen diskutiert. Wenn ein solches Aggregat mit den Stäbchen parallel zur Oberfläche adsorbiert, verschieben sich die Stäbchen gegeneinander. Zusätzlich werden die Stabilität der adsorbierten Aggregate und andere mögliche Konfigurationen untersucht. Um einen Rod-Coil Multiblock mit variabler Zusammensetzung zu studieren, wird eine Feldtheorie entwickelt. Jedes Segment kann entweder steif oder flexibel sein. Das System zeigt drei Phasenzustände, offene Kette, amorphe Globule und flüssig-kristalline Globule. Beim Übergang von amorpher zu flüssig-kristalliner Globule steigt der Anteil an steifen Segmenten rapide an. Dieser Übergang wird durch die isotrope Wechselwirkung zwischen den steifen Segmenten und die anisotrope Oberflächenenergie der Globule verursacht.

Double-stimulus sensitive (temperature and pH) self-assemblable polymers

The rheological properties of block co-polymers in water solution at different pH have been investigated. The block copolymers are based on different architectures containing poly(ethylene glycol), poly(propylene glycol) and different blocks of polymer that change their hydrophobic/hydrophilic behavior as a function of pH. The polymer chains of the starting material were extended at their functional ends with the pH-sensitive units using ATRP; this mechanism of controlled radical polymerization was chosen because of the need to minimize polydispersity and avoid transfer reactions possibly leading to homopolymeric inpurities. The starting material were modified in order to use them as macroinitiator for ATRP. The kinetic of each ATRP reaction has been investigated, in order to be able to synthesize polymers with different degree of polymerization, stopping the reaction when the desired polymers chain length has been reached. We will use polymer chains with different basicity and degree of polymerization to link any possible effect of their presence to the conditions under which they become hydrophobic. It has been shown that the rate of polymerization changes changing the type of macroinitiator and the type of monomer synthesized. The slowest rate of polymerization is the one with the most hindered monomer synthesized using the macroinitiator with the highest molecular weight. The water solubility of the synthesized polymers changes depending on the pH of the solution and on the structure of the polymers. It has been shown using 1H-NMR that some of the synthesized polymers are capable to self-aggregation in water solution. The self-aggregation and the type of aggregation is influenced from the structure of the polymer and from the pH of the solution. Changing the structure of the polymers and the pH it is possible to obtain different type of aggregates in solution. This aggregates differ for the volume occupied from them, and for their hardness. Rheological measurements have been demonstrated that the synthesized polymers are capable to form gel phases. The gelation temperature changes changing the structure of the aggregates in solution and it is possible to correlate the changing in the gelation temperature with the changing in the structure of the polymer.

Extended arm polyphenylene dendrimers

In order to eliminate the de Gennes packing problem, which usually limits the attainable size of dendrimers, a new branching unit containing para-tetraphenylene ethynyl arms has been synthesized and utilized in the preparation of dendrimers of the Müllen type. The divergent principle of synthesis, based on the Dilthey reaction, could be carried up to sixth generation which contains 2776 benzene rings and possesses a diameter in the 27 nm range ("exploded dendrimer"). Monodispersity and dimensions of this and the lower generation species have been studied by MALDI-TOF MS (including the very recent superconducting tunnel junction detector), by size-exclusion chromatography, dynamic light scattering, transmission electron microscopy, and atomic force microscopy. Interesting features, apart from the huge dimension, are the low density and high porosity of these giant molecules which cause extensive aggregation in the gas phase, flattening on solid support (AFM) and the ready incorporation of guest molecules in the condensed phase. Since the synthesis of the para-tetraphenylene arms is quite elaborate, similar dendrimers containing para-terphenylene arms have been prepared; they are accessible more economically ("semi-exploded dendrimers"). It has been shown that they in several aspects mimic the features of the "exploded dendrimers". In order to take advantage of the presence of large internal cavities in this dendrimer type, dendrons containing -C≡C- triple bonds have also been incorporated. Surprisingly, they are readily hydrogenated under the condition of heterogeneous catalysis (Pd/C) which demonstrates the large size of the cavities. As revealed by a quartz microbalance study the post-hydrogenation dendrimers are less prone to incorporate guest molecules than before hydrogenation. Obviously, the more flexible nature of the former reduces porosity, it also leads to significant shrinkage. An interesting perspective is the use of homogeneous hydrogenation catalysts of variable size with the aim of determining the dimension of internal free space.

A molecular approach towards tethered bilayer lipid membranes: synthesis and characterization of novel anchor lipids

Tethered bilayer lipid membranes (tBLMs) are a promising model system for the natural cell membrane. They consist of a lipid bilayer that is covalently coupled to a solid support via a spacer group. In this study, we developed a suitable approach to increase the submembrane space in tBLMs. The challenge is to create a membrane with a lower lipid density in order to increase the membrane fluidity, but to avoid defects that might appear due to an increase in the lateral space within the tethered monolayers. Therefore, various synthetic strategies and different monolayer preparation techniques were examined. Synthetical attempts to achieve a large ion reservoir were made in two directions: increasing the spacer length of the tether lipids and increasing the lateral distribution of the lipids in the monolayer. The first resulted in the synthesis of a small library of tether lipids (DPTT, DPHT and DPOT) characterized by 1H and 13C NMR, FD-MS, ATR, DSC and TGA. The synthetic strategy for their preparation includes synthesis of precursor with a double bond anchor that can be easily modified for different substrates (e.g. metal and metaloxide). Here, the double bond was modified into a thiol group suitable for gold surface. Another approach towards the preparation of homogeneous monolayers with decreased two-dimensional packing density was the synthesis of two novel anchor lipids: DPHDL and DDPTT. DPHDL is “self-diluted” tether lipid containing two lipoic anchor moieties. DDPTT has an extended lipophylic part that should lead to the preparation of diluted, leakage free proximal layers that will facilitate the completion of the bilayer. Our tool-box of tether lipids was completed with two fluorescent labeled lipid precursors with respectively one and two phytanyl chains in the hydrophobic region and a dansyl group as a fluorophore. The use of such fluorescently marked lipids is supposed to give additional information for the lipid distribution on the air-water interface. The Langmuir film balance was used to investigate the monolayer properties of four of the synthesized thiolated anchor lipids. The packing density and mixing behaviour were examined. The results have shown that mixing anchor with free lipids can homogeneously dilute the anchor lipid monolayers. Moreover, an increase in the hydrophylicity (PEG chain length) of the anchor lipids leads to a higher packing density. A decrease in the temperature results in a similar trend. However, increasing the number of phytanyl chains per lipid molecule is shown to decrease the packing density. LB-monolayers based on pure and mixed lipids in different ratio and transfer pressure were tested to form tBLMs with diluted inner layers. A combination of the LB-monolayer transfer with the solvent exchange method accomplished successfully the formation of tBLMs based on pure DPOT. Some preliminary investigations of the electrical sealing properties and protein incorporation of self-assembled DPOT and DDPTT-based tBLMs were conducted. The bilayer formation performed by solvent exchange resulted in membranes with high resistances and low capacitances. The appearance of space beneath the membrane is clearly visible in the impedance spectra expressed by a second RC element. The latter brings the conclusion that the longer spacer in DPOT and the bigger lateral space between the DDPTT molecules in the investigated systems essentially influence the electrical parameters of the membrane. Finally, we could show the functional incorporation of the small ion carrier valinomycin in both types of membranes.

Heteroatom containing polycyclic aromatic hydrocarbons with positive charge - synthesis and characterization

The synthesis and characterization of various heteroatom containing PAHs with positive charge were investigated in this work: 1. A series of 2-phenyl-benzo[8,9]quinolizino[4,5,6,7-fed]phenanthridinylium (PQP) salts with different alkyl chains and anions were synthesized. The synthesis of the extended derivates of PQP salts with two fused benzene rings, 2-phenyl-naphthacene[1,2]quinolizino[3,4,5,6-def]benzo[i]phenanthridinium (DBPQP) tetrafluoroborate was also developed. The self-assembly behavior of these amphiphilic PAHs was investigated in methanolic solution as well as in the bulk. Various aggregates with different morphologies such as fibers, tubes and vesicals were obtained from their solution. All of these morphology changes could be ascribed to the changes in intermolecular interactions which resulting from the difference in the molecular structures such as aromatic cores, alkyl chains and counterions. 2. The synthetic strategy of oxygen containing positively charged PAHs, benzo[5,6]naphthaceno[1,12,11,10-jklmna]xanthylium (BNAX) salts and its dibenzo derivates, DBNAX salts were developed. With a similar method, sulfur containing benzo[5,6]naphthaceno[1,12,11,10-jklmna]thioxanthylium (BNATX) salts were also synthesized. Various BNAX salts with different alkyl chains could be obtained and their supramolecular behavior were investigated. A discotic liquid crystalline behavior was observed for di- (3-25) and tridodecyl (3-27) substituted BNAX salts and both compounds exhibited large unit cell in their 2D-WAXS patterns which could be attributed to the formation of dimer structures. By drop casting their methanolic solution on silicon wafers, similar nanoscaled fibers from monododecyl substituted BNAX bromide 3-24 and DBNAX bromide 3-35 could be observed. 3. A novel synthetic method toward nitrogen containing 14-phenyl-dibenzo[jk,mn]naphtho[2,1,8-fgh]thebenidinium (DBNT) salts was also developed. In this method, the undehydrogenated precursor of DBNT, dibenzoacridinium salt could be produced directly from the reaction between dibenzoxanthenylium derivates and amine/aniline in reasonable yields. Various DBNT salts with different alkyl and alkylphenyl chains on their nitrogen atom were synthesized in this two-step method. The self-assembly behavior of two alkylated DBNT salts, 4-15a and 4-18b was also studied in this work. Compound 4-15a formed nanoscaled fibers and helical aggregates were obtained from 4-18b in their methanolic solutions. 4. Various ionic complexes were derived by complexing PQP and DBPQP cations with different sulfate/sulfonate group containing anionic surfactants. The ionic complexes resulting from the ionic self-assembly (ISA) method exhibited self-assembly behavior which was controllable by the species and shape of cations and anions. Various aggregates such as nanofibers and spherical aggregates could be produced from their methanolic solution in a defined manner conveniently.

Entanglement entropy in restricted integrable spin-chains

In questa tesi abbiamo presentato il calcolo dell’Entropia di Entanglement di un sistema quantistico unidimensionale integrabile la cui rappresentazione statistica é data dal modello RSOS, il cui punto critico é una realizzazione su reticolo di tutti i modelli conformi minimali. Sfruttando l’integrabilitá di questi modelli, abbiamo svolto il calcolo utilizzando la tecnica delle Corner Transfer Matrices (CTM). Il risultato ottenuto si discosta leggermente dalla previsione di J. Cardy e P. Calabrese ricavata utilizzando la teoria dei campi conformi descriventi il punto critico. Questa differenza é stata imputata alla non-unitarietá del modello studiato, in quanto la tecnica CTM studia il ground state, mentre la previsione di Cardy e Calabrese si focalizza sul vuoto conforme del modello: nel caso dei sistemi non-unitari questi due stati non coincidono, ma possono essere visti come eccitazioni l’uno dell’altro. Dato che l’Entanglement é un fenomeno genuinamente quantistico e il modello RSOS descrive un sistema statistico classico bidimensionale, abbiamo proposto una Hamiltoniana quantistica unidimensionale integrabile la cui rappresentazione statistica é data dal modello RSOS.

A regional environmental accounting matrix and integrated environmental economic analyses to support regional planning

This research deals with the deepening and use of an environmental accounting matrix in Emilia-Romagna, RAMEA air emissions (regional NAMEA), carried out by the Regional Environment Agency (Arpa) in an European project. After a depiction of the international context regarding the widespread needing to integrate economic indicators and go beyond conventional reporting system, this study explains the structure, update and development of the tool. The overall aim is to outline the matrix for environmental assessments of regional plans, draw up sustainable reports and monitor effects of regional policies in a sustainable development perspective. The work focused on an application of a Shift-Share model, on the integration with eco-taxes, industrial waste production, energy consumptions, on applications of the extended RAMEA as a policy tool, following Eurostat guidelines. The common thread is the eco-efficiency (economic-environmental efficiency) index. The first part, in English, treats the methodology used to build a more complete tool; in the second part RAMEA has been applied on two regional case studies, in Italian, to support decision makers regarding Strategic Environmental Assessments’ processes (2001/42/EC). The aim is to support an evidence-based policy making by integrating sustainable development concerns at all levels. The first case study regards integrated environmental-economic analyses in support to the SEA of the Regional Waste management plan. For the industrial waste production an extended and updated RAMEA has been developed as a useful policy tool, to help in analysing and monitoring the state of environmental-economic performances. The second case study deals with the environmental report for the SEA of the Regional Program concerning productive activities. RAMEA has been applied aiming to an integrated environmental-economic analysis of the context, to investigate the performances of the regional production chains and to depict and monitor the area where the program should be carried out, from an integrated environmental-economic perspective.

Life Cycle Assessment of Peach Nectar: a comparative analysis between conventional and bioenergy-from-waste integrated food chains

Modern food systems are characterized by a high energy intensity as well as by the production of large amounts of waste, residuals and food losses. This inefficiency presents major consequences, in terms of GHG emissions, waste disposal, and natural resource depletion. The research hypothesis is that residual biomass material could contribute to the energetic needs of food systems, if recovered as an integrated renewable energy source (RES), leading to a sensitive reduction of the impacts of food systems, primarily in terms of fossil fuel consumption and GHG emissions. In order to assess these effects, a comparative life cycle assessment (LCA) has been conducted to compare two different food systems: a fossil fuel-based system and an integrated system with the use of residual as RES for self-consumption. The food product under analysis has been the peach nectar, from cultivation to end-of-life. The aim of this LCA is twofold. On one hand, it allows an evaluation of the energy inefficiencies related to agro-food waste. On the other hand, it illustrates how the integration of bioenergy into food systems could effectively contribute to reduce this inefficiency. Data about inputs and waste generated has been collected mainly through literature review and databases. Energy balance, GHG emissions (Global Warming Potential) and waste generation have been analyzed in order to identify the relative requirements and contribution of the different segments. An evaluation of the energy “loss” through the different categories of waste allowed to provide details about the consequences associated with its management and/or disposal. Results should provide an insight of the impacts associated with inefficiencies within food systems. The comparison provides a measure of the potential reuse of wasted biomass and the amount of energy recoverable, that could represent a first step for the formulation of specific policies on the integration of bioenergies for self-consumption.

Amphiphile Kammpolymere von Poly(2,7-carbazol)

Die vorliegende Dissertation beschreibt die Verschmelzung der Konzepte von konjugierten Polyelektrolyten und amphiphilen Kammpolymeren in Form von konjugierten, Poly(2,7-carbazol)-basierenden Polyelektrolytkammpolymeren mit Poly(L-lysin)seitenketten sowie Alkyl- oder Polyethylenglykolsubstituenten. Die Synthese wurde durch die Suzuki-Polykondensation von monodispersen Makromonomeren erreicht. Hierbei fand die Precursor-Synthesestrategie Anwendung. In diesem Ansatz war die ε-Aminofunktion des Lysins mit einer Benzoyloxycarbonylschutzgruppe geschützt. Der Aufbau der benötigten monodispersen Makromonomere erfolgte durch die Kupplung von Poly(L-lysin)ketten an den Carbazolbaustein mittels eines aktivierten Esters. Eine Besonderheit der hergestellten Kammpolymere lag in den konformativen Eigenschaften seiner einzelnen Komponenten. Dabei konnte die Konformation der Poly(L-lysin)seitenketten infolge ihres Polyelektrolyt- und Peptidcharakters gezielt mit Hilfe des pH-Wertes und der Ionenstärke variiert werden, wohingegen das konjugierte Rückgrat seine steife Konformation beibehielt. Infolge des Polyelektrolytcharakters zeigte sich zudem, dass die Polymere in sauren und neutralen, wässrigen Lösungen zu großen Teilen in Form von Domänenstrukturen auftraten, während im Basischen eine sofortige Aggregation eintrat. Ein weiteres Merkmal der vorgestellten Polyelektrolytkammpolymere war ihr amphiphiler Charakter. Diese Amphiphilie der in dieser Arbeit vorgestellten Polyelektrolytkammpolymere beeinflusste dabei maßgeblich ihre unstrukturierte Anordnung in Lösung, in der festen Phase sowie an Oberflächen.