Who witnesses The Witness? Finding witnesses in The Witness is hard and sometimes impossible

We analyze the computational complexity of the many types of pencil-and-paper-style puzzles featured in the 2016 puzzle video game The Witness. In all puzzles, the goal is to draw a simple path in a rectangular grid graph from a start vertex to a destination vertex. The different puzzle types place different constraints on the path: preventing some edges from being visited (broken edges); forcing some edges or vertices to be visited (hexagons); forcing some cells to have certain numbers of incident path edges (triangles); or forcing the regions formed by the path to be partially monochromatic (squares), have exactly two special cells (stars), or be singly covered by given shapes (polyominoes) and/or negatively counting shapes (antipolyominoes). We show that any one of these clue types (except the first) is enough to make path finding NP-complete ("witnesses exist but are hard to find"), even for rectangular boards. Furthermore, we show that a final clue type (antibody), which necessarily "cancels" the effect of another clue in the same region, makes path finding $\Sigma_2$-complete ("witnesses do not exist"), even with a single antibody (combined with many anti/polyominoes), and the problem gets no harder with many antibodies. On the positive side, we give a polynomial-time algorithm for monomino clues, by reducing to hexagon clues on the boundary of the puzzle, even in the presence of broken edges, and solving "subset Hamiltonian path" for terminals on the boundary of an embedded planar graph in polynomial time.Comment: 72 pages, 59 figures. Revised proof of Lemma 3.5. A short version of this paper appeared at the 9th International Conference on Fun with Algorithms (FUN 2018

Study of random porous morphologies by means of statistical analysis and computer simulations of fluid dynamics

This thesis presents an investigation of porous media by means of simulation techniques and morphological analysis. As a basis for the investigation throughout this work, we use three- dimensional (3D) images of porous structures obtained by imaging techniques, in particular, fo- cused ion beam scanning electron microscopy (FIB-SEM) and confocal laser scanning microscopy (CLSM) for macroporous space, and scanning transmission electron microscopy (STEM) to re- solve mesopores. A set of different morphological methods (chord length distribution (CLD), medial axis analysis (MAA), estimations of geometric, branch and diffusive tortuosities) are applied to capture averaged descriptors of the reconstructed porous samples. Because fluid dy- namics is inherent in many applications of porous media, several techniques are deployed to simulate the fluid dynamics in the reconstructions of porous media. This work includes four chapters that cover three different topics associated with the investigation of fluid dynamics in porous media. Each chapter also represents a separate journal publication. In the first chapter, we perform hydrodynamic dispersion simulations to study the morphology- flow relationship in physical reconstructions of particulate beds as well as in computer-generated packings of monosized spheres. A combination of lattice-Boltzmann and random-walk parti- cle tracking (RWPT) methods were utilized to simulate the flow and mass transport, respec- tively. Based on mean chord length μ and standard deviation σ estimated for CLD, we present a morphological descriptor, σ/μ, that can predict the longitudinal dispersion coefficient for any morphological configuration of packed beds. In the second chapter, we introduce the overall hindrance factor expression, H(λ), that de- scribes transport limitations in mesoporous space of random silica monoliths in dependence of λ, the ratio of solute size to mean pore size. The presented H(λ) is obtained through diffusion simulations of finite-size tracers applying the RWPT technique in three reconstructions of mor- phologically similar porous silica. The expression can also be utilized to assess the hindered diffusion coefficient for any material with similar morphology. In the third chapter, we adopt the lattice-gas mean field density functional theory (MFDFT) to virtually reproduce adsorption/desorption processes in a mesopore network of one of the monoliths from the second chapter. We demonstrate a good qualitative agreement of simulated boundary curves with experimental isotherms with an H2 hysteresis loop obtained for nitrogen at 77 K. We also use 3D images of the phase distribution that can be provided by MFDFT for any relative pressure value in the range 0 < p/p0 ≤ 1 to reveal the relation between hysteresis and phase distribution. In the fourth chapter, we continue using the concept of exploration of phase distribution and perform MFDFT modeling in physically reconstructed geometrical models of two ordered (SBA-15, KIT-6) and one random mesoporous silicas. We conduct a short parametric study of the MFDFT model to find optimal agreement with experimental isotherms in the hysteresis region. We also present simulated boundary curves for both ordered structures with a clear H1 hysteresis loop and for the disordered material with type H2(a) hysteresis. The phase distribution analysis as well as the shape of scanning curves reveal a highly heterogeneous morphology of the random silica. Hence, pore blocking and cavitation phenomena are identified and analyzed

Analysis of Morphology and Transport Characteristics of Mesoporous Materials

Today, mesoporous silica are employed in a wide field of applications. They are used for example as packing materials in chromatography, as support materials for the transport of medical agents within and through the human body, in catalysis or as nanoparticles in nanomedicine. In particular, the mobility of guest molecules within the mesopore system, which is spatially confined by the solid silica framework, is a central aspect in all fields of application. The diffusive transport within and through the mesopores is directly connected to the pore morphology: Due to the spatial confinement of the pore volume and the resulting steric interactions of the guest molecules with the solid silica walls the transport of the molecules is hindered compared to diffusion within free space. This hindrance of diffusion is quantitatively expressed by the effective diffusion coefficient. To make predictions about the transport properties of different individual silica, the formulation of quantitative expressions that describe the relationship between their morphological features and the resulting transport properties is necessary. The pore morphology of the investigated material is often just roughly described by using simplified geometrical models. However, by using simplified geometrical models, individual morphological aspects like constrictions, irregularities or other defects like dead-ends within the pore system, which have a significant influence on the transport properties of an individual material, are not taken into account, often leading to defective and inaccurate results in investigations of morphology-transport relationships. By means of electron tomography (ET), the real three-dimensional (3D) structure of a material can be reconstructed, uncovering morphological details on the nanoscale and making a most accurate investigation of the morphology possible. In this work, the reconstructions are subsequently employed as geometrical models for numerical simulations of hindered diffusion within and through the mesopore system for different tracer sizes. The resulting tracer size dependent functions for the accessible porosity and for the corresponding diffusion coefficients then accurately reflect the morphology-induced hindrance of diffusion for the underlying individual pore system. In the present work, this approach is employed for the investigation of various silica with fundamentally different morphology by means of hindered diffusive transport within and through the mesopores of the correspondent silica framework. The goal of this work is the formulation of general expressions, which enable accurate predictions about the performance of the investigated material for a certain field of application, using only a few material-specific parameters and avoiding the need of an underlying simplified geometrical model. In the first chapter a chromatographic column packed with mesoporous silica particles is investigated in terms of its inter- and intraparticle morphology and its influence on separation characteristics in size exclusion chromatography (SEC). The work is focused on a 2.1 mm I.D. column packed with fully porous ethylene-bridged-hybride-(BEH)particles (1.7 µm particle diameter). The goals of the study include (i) the investigation of morphology-transport/retention relationships for SEC-columns, (ii) the determination of optimal experimental conditions to either maximize peak capacity or assure a constant rate of peak capacity over the whole separation window, (iii) the prediction and comparison of SEC-performance of core-shell particles (nonporous core, porous shell) possessing the same mesopore morphology in their shell as fully porous BEH particles, and (iv) the discussion about possible advantages if the presented reconstruction-simulation approach is employed in order to accelerate method development in SEC. First, the packing microstructure is reconstructed by means of focused ion beam scanning electron microscopy (FIB-SEM) in order to compare the packing characteristics of sections close to the wall of the column with those in the column center. By means of macropore-scale lattice-Boltzmann method (LBM) simulations of the flow profile the influence of the packing microstructure on the flux velocity can be investigated. A clear radial heterogeneity of the packing density is observed, causing an obvious dependence of the flux velocity (obtained from LBM simulations) on the radial position within the column. The flux close to the column walls is much weaker than in the center of the column, where the flux velocity is equal the velocity within unrestricted bulk volume. This radial variation of the flux velocity can be explained by the similar shape of the pressure profile that results from the packing procedure. While single silica particle close to the solid column wall experience an enhanced compressive stress, the pressure is more distributed over the rather flexible particles located in the bulk volume of the column center. Furthermore, the 3D reconstruction of the packing material in the column center obtained by FIB-SEM proofs the existence of a random sphere packing in this area of the column. From the reconstruction, an external (interparticle) porosity of the column of εe = 0.39 is determined. By means of ET, the mesopore volume inside the BEH particles is reconstructed and subsequently employed as geometrical model for diffusion simulations. Numerical simulations of hindered diffusion are conducted within the mesopore volume based on the random-walk particle-tracking-(RWPT-)technique, and the intraparticle porosity ε as well as the local diffusive hindrance factor Kd can be obtained as functions of λ, the ratio of mean mesopore size and tracer diameter. For pointtracers, an accessible intraparticle porosity of ε0 = 0.49 is obtained with this technique. The derived porosity function is compared to the accessible porosity when assuming a cylindrical or a spherical pore geometry, demonstrating a particularly high discrepancy in case of a cylindrical pore model. Furthermore, the analogy between the obtained function for the local diffusive hindrance factor and the well-known RENKIN model is certified. Here, a significant deviance is observed especially for large λ. For pointtracers, an intraparticle tortuosity value of τ0 = 1.95 is furthermore determined from the effective diffusion coefficient at λ = 0. The reconstructed bulk stack (based on FIB-SEM) and the 3D reconstruction of the intraparticle mesopore volume (based on ET) are subsequently employed as geometrical models for diffusion simulations using the hierarchical diffusion model, where tracers of different sizes move through both the macropore volume between the BEH particles and the intraparticle mesopore space, providing tracer size dependent values for the effective diffusivity Dbed. The effective bed diffusivity reflects the interplay of the inter- and intraparticle tracer diffusivities, resulting in a parabolic behavior of Dbed as function of λ. First, small tracers have access to both inter- and intraparticle porosity, causing Dbed to decrease with increasing tracer sizes until at a certain λ, Dbed starts to increase again since the accessible intraparticle porosity becomes significant smaller than the accessible interparticle volume and the diffusion is mainly controlled by the external (interparticle) diffusion. The observed morphology-transport relationships are furthermore used to make presumptions about the performance of SEC-experiments under certain experimental conditions. It is shown that optimal experimental conditions can easily be diagnosed with help of the precedent findings, so that central parameters limiting the performance of SEC-experiments, for example the global peak capacity or the rate of peak capacity, can be controlled. Under certain conditions it is then possible to determine the optimal flow rate for a given temperature and mean pore size in order to maximize the global peak capacity. Additionally, the influence of core-shell particles as packing material on the rate of peak capacity is investigated for different ρ (ratio between the diameter of the nonporous core to the diameter of the whole particle). Here, an increasing peak capacity is found for increasing ρ, though meanwhile a more rapidly closing separation window is observed. This means in praxis that the application of core-shell particles in SEC-experiments is advantageous, if simple analyte mixtures as well as a small amount of high molecular mass analytes are present in the experiment. In the second chapter morphology-transport relationships of two mesoporous silica with ordered pore systems, SBA-15 and KIT-6, are investigated. SBA-15 exhibits a 1D primary pore system, which is composed of hexagonally arranged cylindrical pores, as well as a secondary pore system, where the pores are located at random positions within the amorphous silica walls around the primary pores and therefore allow for diffusive transport in all directions through the ordered pore system. The 3D primary pore system of KIT-6, in contrast, is built of two interpenetrating networks of cylindrical pores, while the secondary pores (mostly micro- and small mesopores) are located like in SBA-15 within the silica walls and therefore provide for a high interconnectivity of the primary pores. First, the structural parameters of both materials are examined by means of X-Ray diffraction analysis (XRD) and nitrogen physisorption analysis. 3D reconstructions of the pore spaces of SBA-15 and KIT-6 obtained from ET are subsequently employed as geometrical models for numerical simulations of diffusive transport through the materials. By means of the RWPT-technique the accessible porosity for pointtracers and the corresponding effective diffusion coefficients can be determined and shown as functions of λ. For pointtracers (λ = 0), accessible porosities of ε0 = 0.69 und ε0 = 0.70 are obtained for SBA-15 and KIT-6, respectively. The diffusive tortuosity can be directly determined for both systems from the respective diffusion coefficient (SBA-15: τ0 = 1.41; KIT-6: τ0 = 1.31). Furthermore, the relationship between the porosity and the corresponding tortuosity as functions of λ are investigated in more detail by considering ε(λ) as a function of τ(λ). It is shown that the global and local diffusion coefficient for hindered diffusion can be evaluated by ARCHIE`s law for small tracer sizes (small λ), while for larger tracers (large λ) the WEISSBERG equation is more appropriate for this purpose. This approach is found to be an equally good alternative to the reconstruction-simulation-approach for the determination of the global and the local diffusion coefficient. With the use of previous findings about ordered silica from this study, the morphology-transport relationships are compared with those found for unordered silica. It is shown that ordered silica give better results in terms of higher selectivities than observed for unordered silica. This comes from the narrower pore size distribution of KIT-6 and SBA-15, which leads to a faster decline of the diffusion with increasing tracer sizes than it is the case for unordered silica. However, the transport efficiency through and within ordered materials is not significantly better than for unordered silica, even in case of a highly interconnected ordered 3D pore structure. Additionally, a narrower pore size distribution causes an enhanced sensitivity against constrictions or other irregularities within the pore system of ordered silica, so that no clear advantage of using ordered silica rather than unordered silica as packing materials in chromatography or as support structures can be pointed out in this study. The third chapter deals with the analysis of morphology-transport relationships for two unordered mesoporous silica of different mean pore sizes, Si60 with a mean pore size of dmeso = 5.9 nm and Si100 with dmeso = 13.0 nm. By means of ET, the pore volumes of Si60 and Si100 are reconstructed and subsequently employed as geometrical models for RWPT-simulations within the mesopores. Similarly to the second chapter, the main aspect of this study is the determination of the accessible porosities as well as the effective diffusion coefficients experienced by passive tracers of different sizes due to the steric and hydrodynamic interaction with the solid silica walls during their diffusion through the mesopore space of each material. With this technique, diffusive tortuosities can be directly determined from the inverse diffusion coefficients for pointtracers (λ = 0). The investigation of the accessible porosities and the diffusion coefficients of both materials as functions of λ shows a stronger hindrance of the tracer diffusion with increasing tracer sizes for Si60 than observed for Si100 for similar tracer sizes. As a result, the access to the mesopores of Si60 can be assumed to be more selective to different tracer sizes, which is of highest interest when it comes to the immobilization or transport of key molecules or the size selective formation of new species within the mesopores, for example. This study is focused on the ring-closing metathesis of a α,ω-diene to the macro(mono)-cyclization (MMC) product and to the oligomer by means of a Hoveyda-Grubbs-catalysator of the second generation, which is immobilized inside the mesopores. Via diffusion ordered nuclear magnetic resonance spectroscopy (DOSY-NMR) the hydrodynamic diameters of the relevant species (MMC product, oligomer, substrate, and catalyst) can be determined and inserted into the previously obtained tracer size dependent functions of the porosities and the diffusion coefficients to allow for accurate predictions about the accessibility of the mesopores for the correspondent species as well as its mobility within the pore system. It is shown that already the first size selective step, the immobilization of the catalyst within the pores, lets assume a significantly smaller catalyst uptake (at similar reaction time) for Si60 than for Si100 due to the substantial spatial confinement and therefore much slower diffusion of the catalyst within and through the pore space of Si60. Because of the larger oligomer size in contrast to the smaller MMC product as well as the smaller substrate, the formation of the MMC product is preferred over that of the oligomer for both materials, which is more pronounced for Si60 than for Si100. With the observed higher selectivity of Si60 comes along a strongly reduced mobility of the species within the mesopores, which may cause a smaller reaction efficiency and yield. The presented approach towards the quantification of transport properties of mesoporous silica is generally applicable to most different micro-reaction systems with various catalysts, substrates and reaction products, to determine the correspondent selectivities and efficiencies of the considered systems. Together with the obtained information and complementary experimental data, it is possible to uncover complex reaction paths and to enable a better understanding of mechanisms within olefin metathesis. The fourth chapter is focused on the investigation of the radial dependence of the morphology within dendritic mesoporous silica nanoparticles (DMSNs). Four different DMSNs are compared, which were all synthesized in a typical microemulsion system with slightly modified reaction parameters. For synthesis, the primary aspect was the independent adjustment of the particle size and the pore size distribution, enabling a pairwise investigation of the four DMSNs: Two of the DMSNs exhibit a comparable pore size distribution, but different particle sizes (i), while the other two DMSNs possess shifted PSDs at similar particle size (ii). By means of ET, 3D reconstructions of the four DMSNs are obtained, serving as geometrical models for the radial analysis of essential morphology-specific descriptors. For radial investigation, concentric hollow spheres with defined radius and coat thickness are cut from the center point of the DMSNs and the segment porosity as well as the chord length distribution (CLD) within the segment mesopore space is determined for different radii. The porosity and the mean chord length (i.e., the mean distance between two opposite silica walls) can then be considered as functions of the outer segment radius. For all DMSNs, a significant porosity loss is observed at the surface of the particles, which is assumed to result from the calcination step during synthesis, leading to a partial melting of the particle surface. The smaller porosity at the particle surface has massive influence on the accessibility of the intraparticle mesopore space for molecules coming from the outside as well as their exit velocity from inside the DMSNs, which needs to be taken into account when considering the applicability and efficiency of DMSNs as drug carriers and for controlled drug release in the human body. Furthermore, the investigation of the mean chord length as a function of the radius reveals a broadening of the pore diameter within increasing radius of the considered segment for one of the DMSNs. Such conical pore shape is particularly convenient, for example if especially large molecules (e.g., DNA or RNA) should have access to the intraparticle mesopore space. In summary, the present work shows that with the underlying approach, i.e., the employment of 3D reconstructions as geometrical models for subsequent diffusion simulations as well as the quantitative investigation of morphological features and the resulting transport properties of an individual material, most different silica materials can be analyzed by means of various problems: The investigation of the effect of synthesis parameters on morphological features, the influence of the pore arrangement and geometries on the efficiency or performance of a material in chromatography or catalysis, for instance, or the radial investigation of the intraparticle pore morphology, to name just a few examples. It is shown that by means of simplified geometric models (e.g., cylindrical or spherical pore models) in most cases the very individual pore structure of mesoporous silica cannot be adequately described. In this work an approach is presented, which enables the quantification of morphology and transport properties for individual materials in a simple way, so that in the next step highly accurate general expressions can be formulated for different classes of silica materials.Mesoporöse Silikamaterialien kommen heutzutage in vielschichtigen Anwendungsbereichen zum Einsatz. Hierzu zählen die Anwendung von Silika als Packungsmaterialien in der Chromatographie, als Supportmaterialien für medizinische Stoffe für deren Transport im und durch den Körper, in der Katalyse oder in Form von Nanopartikeln in der Nanomedizin. Entscheidend ist in allen Anwendungsgebieten die Beweglichkeit von Gastmolekülen in dem Mesoporensystem, welches durch das feste Silikagerüst räumlich begrenzt ist. Der diffusive Transport innerhalb der und durch die Poren ist dabei direkt mit deren Morphologie verknüpft: Aufgrund des begrenzten Porenraums und der daraus resultierenden sterischen Wechselwirkungen der Gastmoleküle mit den festen Silikawänden wird der Transport der Moleküle im Vergleich zur freien Diffusion gehindert. Die Hinderung der Diffusion kommt quantitativ in dem effektiven Diffusionskoeffizienten zum Ausdruck. Um Vorhersagen über die Transporteigenschaften verschiedener individueller Silika treffen zu können, ist es notwendig, quantitative Ausdrücke für die Beziehung zwischen deren Morphologie und den daraus resultierenden Transporteigenschaften zu formulieren. Die Porenmorphologie des betrachteten Materials wird dabei oft nur grob mit Hilfe vereinfachter geometrischer Modelle beschrieben. Allerdings werden durch die Verwendung vereinfachter geometrischer Modelle individuelle morphologische Eigenschaften wie Engstellen, Unregelmäßigkeiten oder andere Defekte wie sogenannte „dead-ends“ (Sackgassen), welche einen entscheidenden Einfluss auf die Transporteigenschaften eines individuellen Materials haben, nicht berücksichtigt, sodass die Ergebnisse solcher Untersuchungen von Morphologie-Transport-Zusammenhängen oft fehlerbehaftet und ungenau sind. Mit Hilfe von Elektronentomographie (ET) kann dagegen die dreidimensionale (3D) Struktur eines Materials exakt rekonstruiert werden, sodass auch morphologische Details im Nanometerbereich aufgedeckt werden können und eine korrekte Untersuchung der Morphologie ermöglicht wird. Die Rekonstruktionen werden in dieser Arbeit anschließend als geometrische Modelle für numerische Simulationen gehinderter Diffusion von Tracern verschiedener Größe durch das Mesoporensystem sowie innerhalb des Systems verwendet. Die resultierenden, von der Größe der Tracer abhängigen, Funktionen für die zugänglichen Porositäten und für die entsprechenden Diffusionskoeffizienten geben dann die morphologiebedingte Hinderung der Diffusion im zugrundeliegenden individuellen Mesoporensystem exakt wieder. In der vorliegenden Arbeit werden mit Hilfe dieses Ansatzes verschiedene Silikamaterialien unterschiedlichster Morphologie hinsichtlich des Einflusses morphologischer Eigenschaften auf den gehinderten diffusiven Transport durch die und innerhalb der Mesoporen des jeweiligen Silikagerüstes analysiert. Ziel ist die Formulierung allgemeiner Gleichungen, die die exakte Vorhersage über die Güte eines Materials für ein bestimmtes Anwendungsgebiet mit Hilfe weniger materialspezifischen Parameter ermöglichen, ohne dass ein vereinfachtes geometrisches Modell von Nöten ist. Im ersten Kapitel wird eine mit mesoporösen Silika-Partikeln gepackten chromatographis

Single particle 2D Electron crystallography for membrane protein structure determination

Proteins embedded into or attached to the cellular membrane perform crucial biological functions. Despite such importance, they remain among the most challenging targets of structural biology. Dedicated methods for membrane protein structure determination have been devised since decades, however with only partial success if compared to soluble proteins. One of these methods is 2D electron crystallography, in which the proteins are periodically arranged into a lipid bilayer. Using transmission electron microscopy to acquire projection images of samples containing such 2D crystals, which are embedded into a thin vitreous ice layer for radiation protection (cryo-EM), computer algorithms can be used to generate a 3D reconstruction of the protein. Unfortunately, in nearly every case, the 2D crystals are not flat and ordered enough to yield high-resolution reconstructions. Single particle analysis, on the other hand, is a technique that aligns projections of proteins isolated in solution in order to obtain a 3D reconstruction with a high success rate in terms of high resolution structures. In this thesis, we couple 2D crystal data processing with single particle analysis algorithms in order to perform a local correction of crystal distortions. We show that this approach not only allows reconstructions of much higher resolution than expected from the diffraction patterns obtained, but also reveals the existence of conformational heterogeneity within the 2D crystals. This structural variability can be linked to protein function, providing novel mechanistic insights and an explanation for why 2D crystals do not diffract to high resolution, in general. We present the computational methods that enable this hybrid approach, as well as other tools that aid several steps of cryo-EM data processing, from storage to postprocessing

Towards artificial photosynthesis : resolving supramolecular packing of artificial antennae chromophores through a hybrid approach

Photosynthesis is a highly cross linked process. However, we can distinguish a set of fundamental building blocks like chlorophylls, which interact to form photosystem, which performs the complex function of water splitting. The key challenge in artificial photosynthesis is to learn how to design systems that can adapt and optimize their topologies in line with self-assembly of natural photosystem. In this thesis I combine different techniques of cross polarization Magic angle spinning Nuclear Magnetic Resonance and Transmission Electron Microscopy with simulation and modeling, to resolve the global packing of molecules which are potential candidates for efficient solar fuel cell devices. This thesis focuses on the packing analysis of three-dimensional structures, which are heterogeneous in nature. I demonstrate a new and general structure determination approach that, in combination with first-principles quantum chemical calculations, establishes the structures of molecularly ordered antenna complexes that lack long-range 3D atomic crystalline order. This is possible despite the absence of a priori information on the space group or atomic coordinates. Chapter 2 describes DATZnS(3ʹ-NMe) parallel stacking in an antiparallel framework with the P2/c space group. 13C CP/MAS NMR yields number of asymmetric sites in the structure and recognition motif. This in conjunction with unit cell parameters and diffraction spots from the Fourier transformation of a TEM image is used to resolve the structure. Supramolecular recognition motif is a characteristic of the packing of the DATZnS(3ʹ-NMe) molecule. The molecular recognition and molecular symmetry steer the packing into a racemic mixture with a c-glide plane and inversion symmetry to release the steric hindrance. Simulation of the LGCP build up curve between specific pairs and electron diffraction were used to validate the proposed packing. Chapter 3 describes the centerosymmetric dimer formation with NMI extending outwards to capture the solar energy. MAS NMR chemical shifts were used to generate a truncated 1,7-perylene-3,4,9,10-tetracarboxylic monoimide dibutylester motif. This motif is further optimized and used for molecular replacement approach to generate a partial 3D electron density approach. The P-1 symmetry obtained from Electron Nano Crystallography is used to graft the naphathelene monoimide substituents. The alkyl chains are modeled using the intermolecular correlation observed in HETCOR. Naphthalene monoimide antennas projecting out from the rows of dimers formed out of rod type D1A2 could capture the light energy and transfer to dimers through FRET. Finally, in chapter 4 C2 molecular symmetry obtained from MAS NMR and DFT modeling is used as the core motif to propose the packing of the DATZnS(4H). Intermolecular correlations obtained from the HETCOR shows the folding of the tails along the phenazine moiety. The analogous modeling showed how the packing could be steered by the NCH3 functional group between antiparallel and parallel dipoles. This understanding opens the way for the evidence based design of light harvesting antenna. In summary, a novel methodology to resolve the structure of chromophore antenna from a structural background with static and dynamic heterogeneity that strongly limits the diffraction response is shown. Furthermore, I anticipate that the insights into packing of the antenna are key to the design of the organic solar fuel cell device in the future.Bio-organic Synthesi

Programmable sphere-tubule frameworks through supramolecular and supracolloidal assembly pathways

The dissertation focuses on the study of a series of new supracolloidal frameworks which can be specifically programmed by the use of tailored supramolecular bile salt derivatives (BSDs) anisotropic structures in combination with isotropic polymeric particles, without resorting to auxiliary functionalization of none the two species. With their high tunability and high repetibility these programmable frameworks could be seen as an innovative pathway for mere nanomaterial preparation and for a deeper understanding of supracolloidal interaction mechanisms among different colloidal units. Three important features can be remarked: 1. The innovative use of anisotropic supramolecular building blocks working as versatile tools for supracolloidal assemblies preparation: the introduction of these mixed systems, based on elementary units composed from isotropic and anisotropic particles, allows to bypass the state of the art constrain given, among the other things, by the need to induce the anisotropy of interaction with satellite chemical functionalizations on the particle surface, particularly influencing the range of geometries accessible and the preparation complexity. 2. The possibility to program the specific framework desired, choosing among a wide range of BSDs with an achieved and solid know-how of their self-assembly behavior and structural characteristics. 3. The possibility to have as outcome intriguing systems in a wide range of configurations possible: from core-corona assemblies to chirally (or non-chirally) decorated supramolecular tubules, from highly ordered frameworks with lattice properties to well-defined crystalline domains in a gel matrix

Nanostructured catalytic films for multiphase microstructured reactors

The application of microstructured catalytic reactors for gas-liquid reactions requires the development of new techniques for the incorporation of highly active catalytic thin films onto their microstructured surfaces. These catalytic thin films may have open porosities even up to 50%. Their application limits the pressure drop over the microreactor in comparison to micro packed beds, it enhances the catalyst accessibility, and it may significantly reduce mass transfer limitations. In this PhD thesis, ordered mesoporous silica and titania films with a thickness of 100 to 400 nm were developed via an evaporation induced self assembly method on different substrates (glass, silicon, titanium). These polymer templated meso¬porous silica films have a narrow pore size distribution and were synthesized with a wide range of pore sizes (2 to 8 nm). A new calcination protocol was developed which allows the complete removal of the surfactant at mild conditions. The thermal and hydro¬thermal stability of the films that were obtained with an ionic surfactant was improved by pH adjust¬ment during hydrolysis and by Al incorporation. Microwave assisted hydro¬thermal synthesis of these ordered microporous films was also investigated in an attempt to reduce the synthesis time from several days to less than 10 hours. The obtained thin films have been loaded with polymetallic nanoparticles with a size of 1 to 3 nm to specifically activate a selected functionality of complex organic molecules. Methods for the deposition and the stabilization of bi-metallic and tri-metallic clusters by adsorption onto the mesoporous thin films have been investigated. A "one pot" sol-gel synthesis of the mesoporous films with embedded colloidal nano¬particles was developed which eliminates an additional impregnation step and produces a uniform distribution of the active components throughout the mesoporous films. Various experimental techniques such as ellipsometric porosimetry, XRD, 2D SAXS, XPS, SEM, and TEM have been applied to obtain insight in the physical and chemical phenomena that determine the performance as well as the stability of the thin films. The activity and the selectivity of the resulting catalytic thin films have been investigated in the batch and in the continuous mode in the hydrogenation of citral and phenylacetylene. The latter was done in a 10 m long micro capillary (i.d. 250 µm) with a catalytic thin film deposited onto its inner channel wall surface. It was shown that the selectivity towards the target product can be changed by varying the metal ratio in the bimetallic nanoparticles. The high stability of these catalytic thin films allows their further implementation in fine chemicals synthesis using microstructured reactors