Mechanochemistry of fluoride solids: from mechanical activation to mechanically stimulated synthesis

This lecture text is focused on the comparatively young field of mechanochemistry of fluoride solids, considering both their mechanical activation and their mechanochemical synthesis. Beside a literature survey, the mechanochemical synthesis of binary fluorides MF2, MF3, of complex fluorides MMgF4, of solid solutions Ma xMb 1−xF2 or M1− xLnxF2+x (Ln: Y, Eu) and of fluorine-containing coordination polymers is presented. Owing to their interesting potential applications in the field of fluoride ion conductivity or luminescence properties when doped, most of the given examples are alkaline earth metal compounds. A short historical survey, remarks on peculiarities and consequences of mechanical activation as well as the necessary technical equipment for mechanochemical reactions precede the section.Peer Reviewe

Effects of phase Separation and devitrification processes in oxide glasses on ESR spectra

The consequences of phase Separation and devitrification processes for the ESR patterns of Fe³⁺ ions and oxygen hole centres in giassy and glassy-crystalline Systems are discussed. Analysis of the Fe³⁺ spectra by Simulation (including 4th order terms) allows their model-based Interpretation for homogeneous, phase-separated and devitrified samples as well. It is even possible to estimate the ratio of Fe³⁺ ions incorporated into the giassy matrix to those localized in the crystalline phase. An influence of irreversible structural reorganization in glasses on γ-irradiation-induced oxygen hole centres is detectable by studying their Saturation behaviour For the example of a barium Silicate glass studied here, pronounced passage effects could be detected at 77 K. In contrast, a devitrified sample of the same composition after γ Irradiation yielded the same spectral pattern at low microwave power, but only Saturation broadening was to be observed when rising the microwave power. In an annealed sample of anorthite composition (in mol%: 25CaO, 25AI₂O₃, 50SiO₂) progressive crystal growth was detectable using Fe³⁺ ions as probes

Chlorodefluorination of Fluoromethanes and Fluoroolefins at a Lewis Acidic Aluminum Fluoride

Chlorodefluorination reactions of fluoromethanes and fluoroolefins catalysed by the highly Lewis acidic nanoscopic aluminum chlorofluoride (ACF, AlClxF3−x, x≈0.05–0.3) in the presence of ClSiEt3 were studied. Both fluoromethanes and fluoroolefins convert under mild reaction conditions by fluorine-chlorine exchange steps into chlorinated fluoro derivatives. MAS NMR studies provided information on the interaction of silanes and hexafluoropropene with the ACF surface.CRC 1349Deutsche Forschungsgemeinschaft (DFG), German Research FoundationDeutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659Chinese Scholarship CouncilPeer Reviewe

Structure and properties of fluorinated and non‐fluorinated Ba‐coordination polymers – the position of fluorine makes the difference

As the most electronegative element, fluorine has a strong influence on material properties such as absorption behaviour or chemical and thermal stability. Fluorine can be easily integrated into coordination polymers (CPs) via a fluorinated acetate, here trifluoroacetate in Ba(CF3COO)2, or directly via a metal fluorine bond (BaF(CH3COO)). In the present study both possibilities of fluorine integration were tested and their effect on structure and properties of barium coordination polymers was investigated in comparison with the non-fluorinated barium acetate (Ba(CH3COO)2). In addition to the study of their thermal behaviour and their decomposition temperature, the CPs structures were tested for their application as possible anode materials in lithium ion batteries and for their sorption of water and ammonia. The properties of the CPs can be traced back to the individual structural motifs and could thus trigger new design ideas for CPs in LIBs and/or catalysis.HU BerlinBAMPeer Reviewe

Niobium pentoxide nanomaterials with distorted structures as efficient acid catalysts

Niobium pentoxides are promising acid catalysts for the conversion of biomass into fuels and chemicals. Developing new synthesis routes is essential for designing niobium pentoxide catalysts with improved activity for specific practical processes. Here we show a synthesis approach in acetophenone, which produces nanostructured niobium pentoxides with varying structure and acidity that act as efficient acid catalysts. The oxides have orthorhombic structures with different extents of distortions and coordinatively unsaturated metal atoms. A strong dependence is observed between the type and strength of the acid sites and specific structural motifs. Ultrasmall niobium pentoxide nanoparticles, which have strong Brønsted acidity, as well as Lewis acidity, give product yields of 96% (3 h, 140 °C, 100% conversion), 85% (3 h, 140 °C, 86% conversion), and 100% (3 h, 110 °C, 100% conversion) in the reactions of furfuryl alcohol, 5-(hydroxymethyl)furfural, and α-angelica lactone with ethanol, respectively.Peer Reviewe

An Amorphous Teflate Doped Aluminium Chlorofluoride: A Solid Lewis‐Superacid for the Dehydrofluorination of Fluoroalkanes

An anion-doped aluminium chlorofluoride AlCl0.1F2.8(OTeF5)0.1 (ACF-teflate) was synthesized. The material contains pentafluoroorthotellurate (teflate) groups, which mimic fluoride ions electronically, but are sterically more demanding. They are embedded into the amorphous structure. The latter was studied by PDF analysis, EXAFS data and MAS NMR spectroscopy. The mesoporous powder is a Lewis superacid, and ATR-IR spectra of adsorbed CD3CN reveal a blue-shift of the adsorption band by 73 cm−1, which is larger than the shift for SbF5. Remarkably, ACF-teflate catalyzes dehydrofluorination reactions of monofluoroalkanes to yield olefins in C6D6. In these cases, no Friedel-Crafts products were formed.German Research Foundation http://dx.doi.org/10.13039/501100001659Diamond Light Source http://dx.doi.org/10.13039/100011889German Research Foundation http://dx.doi.org/10.13039/501100001659Peer Reviewe

An Amorphous Teflate Doped Aluminium Chlorofluoride: A Solid Lewis‐Superacid for the Dehydrofluorination of Fluoroalkanes

An anion‐doped aluminium chlorofluoride AlCl0.1F2.8(OTeF5)0.1 (ACF‐teflate) was synthesized. The material contains pentafluoroorthotellurate (teflate) groups, which mimic fluoride ions electronically, but are sterically more demanding. They are embedded into the amorphous structure. The latter was studied by PDF analysis, EXAFS data and MAS NMR spectroscopy. The mesoporous powder is a Lewis superacid, and ATR‐IR spectra of adsorbed CD3CN reveal a blue‐shift of the adsorption band by 73 cm−1, which is larger than the shift for SbF5. Remarkably, ACF‐teflate catalyzes dehydrofluorination reactions of monofluoroalkanes to yield olefins in C6D6. In these cases, no Friedel‐Crafts products were formed

Studies on the local structure of the F ∕ OH site in topaz by magic angle spinning nuclear magnetic resonance and Raman spectroscopy

The mutual influence of F and OH groups in neighboring sites in topaz (Al2SiO4(F,OH)2) was investigated using magic angle spinning nuclear magnetic resonance (MAS NMR) and Raman spectroscopy. The splitting of 19F and 1H NMR signals, as well as the OH Raman band, provides evidence for hydrogen bond formation within the crystal structure. Depending on whether a given OH group has another OH group or fluoride as its neighbor, two different hydrogen bond constellations may form: either OH⋯O⋯HO or F⋯H⋯O. The proton accepting oxygen was determined to be part of the SiO4 tetrahedron using 29Si MAS NMR. Comparison of the MAS NMR data between an OH-bearing and an OH-free topaz sample confirms that the 19F signal at −130 ppm stems from F− ions that take part in H⋯F bonds with a distance of ∼ 2.4 Å, whereas the main signal at −135 ppm belongs to fluoride ions with no immediate OH group neighbors. The Raman OH sub-band at 3644 cm−1 stems from OH groups neighboring other OH groups, whereas the sub-band at 3650 cm−1 stems from OH groups with fluoride neighbors, which are affected by H⋯F bridging. The integrated intensities of these two sub-bands do not conform to the expected ratios based on probabilistic calculations from the total OH concentration. This can be explained by (1) a difference in the polarizability of the OH bond between the different hydrogen bond constellations or (2) partial order or unmixing of F and OH, or a combination of both. This has implications for the quantitative interpretation of Raman data on OH bonds in general and their potential use as a probe for structural (dis-)order. No indication of tetrahedrally coordinated Al was found with 27Al MAS NMR, suggesting that the investigated samples likely have nearly ideal Al/Si ratios, making them potentially useful as high-density electron microprobe reference materials for Al and Si, as well as for F

dolls/puppets in threat scenarios

Puppen in Bedrohungsszenarien – so lautet der Themenschwerpunkt der ersten Ausgabe der interdisziplinären online-Zeitschrift "denkste: puppe / just a bit of: doll" zu Mensch-Puppen-Diskursen (Akronym: de:do). Die Bezeichnung ‚Puppe’ steht dabei für anthropomorphe ,Wesen’ und Artefakte in all ihren unterschiedlichen Erscheinungsformen und der Begriff der Bedrohung wird hier weit gefasst. Ausgangspunkt der Entscheidung für diesen Fokus war die Annahme, dass Puppen und puppenaffinen Artefakten sowohl in Zeiten existenzieller Bedrohung als auch in Phasen innerpsychischer Beunruhigung und Irritation eine besondere Bedeutung zukommt. Die hier einbezogenen Beiträge stammen aus unterschiedlichen Fachdisziplinen und eröffnen in der bewusst nicht disziplinär ausgerichteten Zusammenstellung reizvolle multiperspektivische Mensch-Puppen-Diskurse. Dabei sind nicht nur die hier angesprochenen Themenbezüge, sondern auch die jeweiligen methodischen Zugänge ausgesprochen heterogen. So werden Puppen-Narrative aufgegriffen, die beispielsweise innerhalb der Literaturwissenschaft an die lange Tradition von Puppen-Erzählungen anknüpfen, aber auch solche, die aktuell in den Diskursen über Zukunftsszenarien und neue Technologien mittels verschiedener medialer Formate und/oder künstlerischer Aktionen für Diskussionsstoff sorgen. Ein erster thematischer Fokus liegt auf der Bedeutung von Puppen im Zuge der Erfahrung von Bedrohung und Verlusten im Kontext von Krieg, Flucht und Verfolgung in politisch unsicheren Zeiten. Hier werden aus verschiedenen fachdisziplinären Perspektiven unterschiedliche Facetten von Bedrohungsszenarien angesprochen. So geht es aus theaterwissenschaftlicher Sicht um zwei Inszenierungen aus dem Bereich des Objekt- und Materialtheaters, in denen bedrohliche Kriegsdarstellungen mittels Plastikpuppen bzw. amorphen Materials aufbereitet werden. Aus psychologischer Perspektive kommen Rollen und Funktionen von Puppen als Übergangsobjekte im Kontext von Umbrüchen, Krieg und Gewalt zur Sprache. In zwei literaturwissenschaftlichen Beiträgen wird jeweils ein Roman aus der Kinder- und Jugendliteratur analysiert, in denen in einem Fall eine Puppe zur psychischen Stabilisierung der literarischen Protagonistin beiträgt und im anderen Fall das Schicksal der Puppe die Geschichte von Abschied und letztendlicher Vernichtung ihrer Besitzerin erzählt und symbolisiert. Und schließlich geht es um den Stellenwert von Puppen und Teddys in verschiedenen Kinderzeitschriften, die – in den politisch unsicheren Zeiten zwischen und nach den beiden Weltkriegen – Identifikationsfiguren und Interaktionspartner für Kinder sein können. Ein zweiter Fokus thematisiert Puppen und ihre Narrative im Kontext verschiedener aversiver Erfahrungen sowie in Zeiten psychischer Irritation. So geht es zum einen um die literaturwissenschaftliche Sicht auf die Bedeutung und Wirkung von Puppen in zwei ‚klassischen’ Puppenerzählungen: „"Nussknacker und Mausekönig" von E.T.A. Hoffmann und "Romeo und Julia auf dem Dorfe" von Gottfried Keller. Zum anderen werden in verschiedenen Beiträgen Entgrenzungs-, Transformations- und Identitätsfragen in Mensch-Puppen-Bezügen aus medien- und kunstwissenschaftlicher sowie kinderliterarischer Perspektive angesprochen, in denen Puppen in Gestalt von Androiden, Kunstwesen oder anthropomorphen Figuren agieren und dabei selber Irritationen auslösen oder Versuche darstellen, Antworten auf beunruhigende Fragen zu finden. Über den Themenschwerpunkt hinaus finden sich zudem eine Reihe weiterer Beitragsformen zu verschiedenen puppenbezogenen Themen und Praxen, die noch einmal das breite Spektrum unterschiedlicher Puppen-Narrative und Zugangsformen dokumentieren: So beschäftigt sich ein freier Beitrag mit dem Puppenspiel als strukturiertes Therapieangebot für Kinder, bei den Miszellen findet sich eine Skizze zu Marlene Dietrich und ihren Puppen sowie ein kurzer Essay zu einer biographischen Erinnerung, ein Interview mit der Begründerin des Berliner Puppentheaters bubales veranschaulicht Möglichkeiten der dramatischen und poetischen Umsetzung von Puppen-Themen, im Diskussionsforum wird ein kritischer Blick auf "Barbie als Diskursmaschine" geworfen und eine Rezension zum Ausstellungskatalog "From Her Wooden Sleep von Ydessa Hendels" lotet Chancen und Grenzen der künstlerischen Arbeit mit Puppen-Artefakten aus.Dolls / Puppets in Threat Scenarios – this is the topic focus of the first issue of the interdisciplinary online magazine "denkste: puppe / just a bit of: doll" on human-doll discourses (acronym: de: do). The term ’doll’ stands for anthropomorphic ’beings’ and artifacts of all kinds and the concept of threat is broadly defined. This focus was stimulated by the assumption that dolls and doll-related artifacts are of particular importance in times of existential threat as well as in phases of inner psychic anxiety and irritation. Yet, the basically ambiguous character of the doll does not necessarily determine a clear effect, so that its usability always involves a certain blurriness and ambivalence. In threatening and adverse situations dolls can act as companions and significant (transitional) objects, thus allowing psychic stabilization, security, and attachment as well as enabling (inner) autonomy, agency, and developmental processes. But dolls can also be a crucial component of threat scenarios themselves and act frightening in this function. All this applies not only to material and real existing dolls and puppets, but also to dolls as literary and / or media figures as well as to doll narratives of any kind. The articles included here come from different disciplines and open up an appealing and deliberately non-disciplinary oriented human-doll discourse from multiple perspectives. Accordingly, the relevant themes as well as the respective methodological approaches are highly heterogeneous. Thus, some contributions follow the long tradition of doll narratives in literature while others discuss currrent topics and discourses on future scenarios and new technologies by means of various doll-related media formats and / or art performances. A first thematic focus is on the significance of dolls in experiencing threats and losses in the context of war, flight and persecution in times of political uncertainty. Here, different facets of threat scenarios are addressed from different disciplinary perspectives. From the field of object and material theater two productions are introduced in which menacing war scenes are processed by means of plastic dolls or amorphous material. From a psychological perspective, dolls are discussed in their roles and functions as transitional objects within the context of upheaval, war and violence. Furthermore, two literary contributions analyze novels from children’s and youth literature. One story deals with a doll which contributes to the psychological stabilization of the literary protagonist. The other story tells of a girl and her doll which symbolizes the final farewell and eventual annihilation of the (Jewish) girl. Finally, the role of dolls and teddy bears in various children’s magazines is exemplified, which serve as identification figures and interaction partners for children in the politically unstable times between and after the two World Wars. A second focus deals with dolls and their narratives in the context of various aversive experiences as well as in times of psychological irritation. Two contributions analyze the meaning and effect of dolls in two ’classical’ doll narratives from a literary perspective: "Nussknacker und Mausekönig" by E.T.A. Hoffmann and "Romeo und Julia auf dem Dorfe" by Gottfried Keller. Further contributions address questions of ego dissolution, transformation and identity processes in human-doll relations from various perspectives such as media, art and children’s literature. Here, dolls appear as androids, artistic or anthropomorphic figures which cause irritation themselves or attempt to find answers to disturbing human-doll questions. In addition to the main topic, there are also a number of other sections and types of contributions on various doll-related topics and practices which once again document the wide range of doll narratives and possible forms of access: For example, a free contribution deals with doll play as a structured therapy for children, the miscellaneous section includes a portrait of Marlene Dietrich and her dolls as well as a short essay on a biographical reminiscence, an interview with the founder of the Berlin Puppet Theater bubales illustrates the possibilities of dramatic and poetic realization of puppet and doll narratives, a critical view on "Barbie as a discourse machine" is presented in the discussion forum and a review of the exhibition catalog "From Her Wooden Sleep by Ydessa Hendels" explores opportunities and limits of artistic work with doll artifacts