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π-Conjugated two-dimensional covalent organic frameworks (2D COFs) are emerging as a novel class of electro-active materials for (opto-)electronic and chemiresistive sensing applications. However, understanding the intricate interplay between chemistry, structure and conductivity in π-conjugated 2D COFs remains elusive. Here, we report a detailed charac-terization for the electronic properties of two novel samples consisting of Zn- and Cu-phthalocyanine-based pyrazine-linked 2D COFs. These 2D COFs are synthesized by condensation of metal-phthalocyanine (M=Zn and Cu) and pyrene derivatives. The obtained polycrystalline-layered COFs are p-type semiconductors both with a band gap of ~1.2 eV. Mobilities up to ~5 cm²/Vs are resolved in the dc limit, which represent a lower threshold induced by charge carrier localization at crystalline grain boundaries. Hall Effect measurements (dc limit) and terahertz (THz) spectroscopy (ac limit) in combination with den-sity functional theory (DFT) calculations demonstrate that varying metal center from Cu to Zn in the phthalocyanine moiety has a negligible effect in the conductivity (~5×10⁻⁷ S/cm), charge carrier density (~10¹² cm⁻³), charge carrier scattering rate (~3×10¹³ s⁻¹), and effective mass (~2.3m₀) of majority carriers (holes). Notably, charge carrier transport is found to be aniso-tropic, with hole mobilities being practically null in-plane and finite out-of-plane for these 2D COFs.

Comprehensive understanding of chirality has played a crucial role for ensuring safety and efficacy of drug products. In many cases, two optical configurations of a chiral molecule exhibit substantially different physiological behaviour, and thus the preparation of single enantiomers has become as an essential topic in the pharmaceutical industry.1-2 Enantiomerically pure compounds could generally be achieved by separation from racemic mixtures or direct synthesis of enantiopure molecules. Either way, chiral materials which are employed as stationary phase in chiral columns or chiral catalysis, are a basic condition to decide to enantiomeric excess of resulting mixtures. Despite obtaining high enantiomeric purity, the chiral separation of racemic mixtures is considered as an expensive and inefficient approach due to undesired enantiomers, while asymmetric synthesis, which enables dominant formation of the single enantiomers, is an atom-economical method. However, the development of efficient heterogeneous chiral catalysts has been still required further investigations to provide more potential options for asymmetric organic reactions, especially carbon-carbon bond formations, which are key steps in organic synthesis.1-3 In recent years, metal-organic frameworks have emerged as one of the most intriguing solid porous materials. Together with the highly active catalytic centers, wide structural and functional variations, MOFs have been successfully employed as heterogeneous catalysts for a variety of organic transformations.4-5 However, very few achievements relating to MOFs as asymmetric catalysts have been reported to date because of their low thermal and chemical stabilities. Such solid stable frameworks, the Zr-MOFs offers great opportunities for designing novel effective asymmetric catalysts.1, 6-9 This is an interesting, but also challenging topic with many open issues: • How can we introduce effectively enantiopure active sites into Zr-MOFs? • Are there any posit

Nanoparticle (NP) implementation in industry has increased during the last years. However, the consequences of NP release to the environment have not been fully understood yet and long-term effects are hardly predictable. Information regarding a possible NP uptake by organisms is urgently needed. Here, we investigate the uptake of presynthesized AuNPs of different diameters by living diatoms. To better understand the influence of NPs on diatoms, cells were monitored in vivo using Surface Enhanced Raman Spectroscopy (SERS). By 3D Raman imaging, AuNPs with diameters ≥50 nm could clearly be localized inside the cells, whereas smaller AuNPs were never detected in the cell interior. This indicates a size-dependent uptake mechanism that comes along with different toxicities. As diatoms present an essential source of the marine food chain, this observation is relevant not only for diatoms themselves but also for higher organisms.

The ultimate goal of this work is providing insights into fundamental (physico-) chemical (redox) behavior of hexavalent uranium (U(VI)), trivalent europium (Eu(III)) and selenium (Se), and upon their interaction with ubiquitous small biomolecules (in case of U(VI) and Eu(III)) or alkaline earth metal ions (in case of Se(IV) and Se(VI)) by application of Nuclear Magnetic Resonance (NMR) spectroscopy. NMR spectroscopy is a powerful method proving its usefulness also to environmental and nuclear waste related studies in aqueous solutions by determination of (potential) binding sites, molecular structures (even conformation and configuration) as well as intra- and intermolecular dynamics, (redox) reaction pathways and mechanisms. The present work comprises extensive NMR spectroscopic investigations in aqueous (D2O) solutions on (i) glutathione (GSH) and glutathione disulfide (GSSG) interactions with trivalent lanthanides (Ln(III), particularly Eu(III)) and U(VI), (ii) molecular structures of citrate (Cit) complexes of U(VI), and their reactions upon light-irradiation, as well as (iii) pH- and temperature-dependent speciation of selenium oxyanions, i.e., Se(VI) (selenate) and Se(IV) (selenite and, notably, hydrogen selenite) as well as Se(VI) and Se(IV) interaction with alkaline earth metal ions. These investigations are supported by time-resolved laser-induced fluorescence spectroscopy (TRLFS), ultraviolet-visible-near infrared (UV-Vis-NIR), IR/Raman, and extended X-ray absorption fine structure (EXAFS) spectroscopy, transmission electron microscopy (TEM), as well as quantum chemical calculations on density functional theory (DFT) level. For NMR spectroscopic data on GSH/GSSG complexation towards both Eu(III) and U(VI) are lacking, the herein presented results are new, and nicely complement other spectroscopic studies. Ln(III) complexes of GSH are characterized by their high solubility at least up to 300 mM and pD 5. However, the formation constant of the Eu(III)–GSH 1

Diatoms are unicellular, eukaryotic microalgae inhabiting nearly all aquatic habitats. They are famous for their micro- and nanopatterned silicabased cell walls, which are envisioned for various technologic purposes. Within this review article, we summarize recent in vivo modifications of diatom biosilica with respect to the following questions: (i) Which metals are taken up by diatoms and eventually processed into nanoparticles (NPs)? (ii) Are these NPs toxic for the diatoms and––if so––what factors influence toxicity? (iii) What is the mechanism underlying NP synthesis and subsequent metabolism? (iv) How can the obtained materials be useful for materials science?

Die vorliegende Arbeit befasst sich mit der Synthese phosphorhaltiger anorganischer Verbindungen in ionischen Flüssigkeiten (engl. ionic liquids, ILs) und legt einen Schwerpunkt auf die Untersuchung der grundlegenden mechanistischen Abläufe, insbesondere auf die Aktivierung von elementarem Phosphor in ILs. Durch die Kombination spektroskopischer und theoretischer Methoden wurde ausführlich das chemische Verhalten von Phosphorhalogeniden in halogenidhaltigen ILs analysiert. Es konnte gezeigt werden, dass nach der Auflösung von rotem Phosphor mit Iod ein Gleichgewicht in der Lösung vorliegt, welches zu der Bildung von Tetrachlorophosphat führt. Insgesamt weist der beobachtete, dynamische Koordinationsprozess der Liganden Ähnlichkeiten zu einer strukturellen Diffusion bzw. Grotthuss-Diffusion auf. Diese Mischungen könnten somit potenziell als kostengünstige Elektrolyte verwendet werden. In weiteren Untersuchungen gelang es, aus Cu und rotem Phosphor in halogenidhaltigen ILs reproduzierbar und in hoher Reinheit Cu3−xP (x = 0,05) zu synthetisieren. Die Optimierung der Reaktion ermöglichte dabei Ausbeuten von über 99 %. Während der Reaktion kommt es zu einer IL-induzierten nukleophilen Aktivierung des roten Phosphors, wodurch hochreaktive P4-Moleküle gebildet werden. Durch die direkte Verwendung von P4 in ILs konnte nachfolgend erstmals kupferarmes Cu3−xP (0,1 < x < 0,7) gezielt synthetisiert werden, ohne das phosphorreiche Nebenprodukte gebildet wurden. Die elektrochemische Charakterisierung unterschiedlicher Cu3−xP-Phasen als Anodenmaterial in Lithium-Ionen-Akkumulatoren zeigte, dass sich das chemische Verhalten gegen Li mit der Zusammensetzung des Materials ändert. Da sich kupferarmes Cu3−xP durch eine höhere Kapazität und kupferreiches Material durch eine bessere Zykelnstabilität auszeichnet, erlauben die Ergebnisse dieser Arbeit die weitere Optimierungen dieses Materials für den Einsatz in Akkumulatoren.:1. Motivation und Einleitung 1 1.1. Klassische Flussmittel in d