Ionische Flüssigkeiten auf Basis von komplexen Übergangsmetallhalogeniden

In der vorliegenden Arbeit wurden neue d- und f-Elemente enthaltende ionische Fluessigkeiten auf Basis von 1-Alkyl-3-Methylimidazolium(Cxmim+)-halogeniden und Thiocyanaten synthetisiert und charakterisiert. So konnte der strukturelle Aufbau ionischer Fluessigkeiten mit komplexen Anionen auf Basis von V3+, Cu+ und Hg2+ bestimmt werden. Dabei zeigt sich im Falle von Quecksilber sowohl eine Beeinflussung der Koordinationssphaere des Metallions in Abhaengigkeit von der Kettenlaenge des Kations als auch durch die Wahl des Halogenids: waehrend das Quecksilber von Cl- bevorzugt in einer 3+2 Koordination von fuenf Liganden in Form einer trigonalen Bipyramide umgeben ist, so wird die tetraedrische Koordination in den Iodidverbindungen praeferiert. Bei den Bromiden ist die Kettenlaenge des Kations auf die lokale Umgebung des Metallzentrums entscheidend. In dem durch Reaktion mit Methanol und [C4mim]Cl zugaenglichen, aus drei Cr3+ Ionen aufgebauten, spinfrustriertem Cluster Cr3Cl9 konnten mittels Roentgeneinkristalldiffraktometrie und Messung der magnetischen Suszeptibilitaet die Bindungsverhaeltnisse aufgeklaert werden. Durch Hochmagnetfeldmessungen bis zu 60 Tesla konnten die energetischen Zustaende des Spinsystems soweit aufgespalten werden, bis ein Crossover dieser Zustaende beobachtet wurde, welcher mit Aenderungen der dielektrischen Konstante gekoppelt ist. Die Ergebnisse werden durch Bandstrukturrechnungen untermauert. Durch den Einbau von Cu+ in die Strukturen von [C4mim]3[LnCl6] (Ln = Gd, Tb, Dy) wurden neue Materialen mit außergewoehnlichen lumineszenten Eigenschaften erhalten. Dabei laesst sich ein Energieuebertrag vom Imidazoliumring auf das Cu+ Ion beobachten. Die Emissionsspektren sind breitbandig und temperaturabhaengig. Die Emission von Tb3+ und Dy3+ wird davon nicht beeinflusst. In den bei Raumtemperatur fluessigen ILs auf Basis von [C6mim]SCN und Dy(SCN)3 konnte das hohe magnetische Moment des Dysprosiums auf die Fluessigkeit uebertragen werden, so dass sich die ionische Fluessigkeit durch Magnetfelder manipulieren laesst. Die lumineszenten Eigenschaften des Dy3+ verleihen den Fluessigkeiten darueber hinaus optische Eigenschaften. Die Lebensdauer des angeregten Zustandes liegt mit 48 Mikrosekunden weit ueber dessen Lebensdauer in waessrigen Loesungen

Phosphonium Chloromercurate Room Temperature Ionic Liquids of Variable Composition

The system trihexyl(tetradecyl)phosphonium ([P66614]Cl)/mercury chloride (HgCl2) has been investigated by varying the stoichiometric ratios from 4:1 to 1:2 (25, 50, 75, 100, 150, and 200 mol % HgCl2). All investigated compositions turn out to give rise to ionic liquids (ILs) at room temperature. The prepared ionic liquids offer the possibility to study the structurally and compositionally versatile chloromercurates in a liquid state at low temperatures in the absence of solvents. [P66614]2[HgCl4] is a simple IL with one discrete type of anion, while [P66614]{HgCl3} (with {} indicating a polynuclear arrangement) is an ionic liquid with a variety of polyanionic species, with [Hg2Cl6]2– apparently being the predominant building block. [P66614]2[Hg3Cl8] and [P66614][Hg2Cl5] appear to be ILs at ambient conditions but lose HgCl2 when heated in a vacuum. For the liquids with the compositions 4:1 and 4:3, more than two discrete ions can be evidenced, namely, [P66614]+, [HgCl4]2–, and Cl– and [P66614]+, [HgCl4]2–, and the polynuclear {HgCl3}−, respectively. The different stoichiometric compositions were characterized by 199Hg NMR, Raman- and UV–vis spectroscopy, and cyclic voltammetry, among other techniques, and their densities and viscosities were determined. The [P66614]Cl/HgCl2 system shows similarities to the well-known chloroaluminate ILs (e.g., decrease in viscosity with increasing metal content after addition of more than 0.5 mol of HgCl2/mol [P66614]Cl, increasing density with increasing metal content, and the likely formation of polynuclear/polymeric/polyanionic species) but offer the advantage that they are air and water stable

Solution-Based Synthesis of GeTe Octahedra at Low Temperature

GeTe octahedra were prepared by reaction of equimolar amounts of GeCl2·dioxane and Te(SiEt3)2 in oleylamine, whereas a slight excess of the Te precursor yielded GeTe octahedra decorated with elemental Te nanowires, which can be removed by washing with TOP. The mechanism of the GeTe formation is strongly influenced by the solvent. The expected elimination of Et3SiCl (dehalosilylation) only occurred in aprotic solvents, whereas Te(SiEt3)2 was found to react with primary and secondary amines with formation of silylamines. Temperature-dependent studies on the reaction in oleylamine showed that crystalline GeTe particles are formed at temperatures higher than 140 °C. XRD, SAED, and HRTEM studies proved the formation of rhombohedral GeTe nanoparticles. These findings were confirmed by a single-crystal and powder X-ray analysis. The rhombohedral structure modification was found, and the structure was solved in the acentric space group R3m

Genome-wide association identifies nine common variants associated with fasting proinsulin levels and provides new insights into the pathophysiology of type 2 diabetes.

OBJECTIVE: Proinsulin is a precursor of mature insulin and C-peptide. Higher circulating proinsulin levels are associated with impaired β-cell function, raised glucose levels, insulin resistance, and type 2 diabetes (T2D). Studies of the insulin processing pathway could provide new insights about T2D pathophysiology. RESEARCH DESIGN AND METHODS: We have conducted a meta-analysis of genome-wide association tests of ∼2.5 million genotyped or imputed single nucleotide polymorphisms (SNPs) and fasting proinsulin levels in 10,701 nondiabetic adults of European ancestry, with follow-up of 23 loci in up to 16,378 individuals, using additive genetic models adjusted for age, sex, fasting insulin, and study-specific covariates. RESULTS: Nine SNPs at eight loci were associated with proinsulin levels (P < 5 × 10(-8)). Two loci (LARP6 and SGSM2) have not been previously related to metabolic traits, one (MADD) has been associated with fasting glucose, one (PCSK1) has been implicated in obesity, and four (TCF7L2, SLC30A8, VPS13C/C2CD4A/B, and ARAP1, formerly CENTD2) increase T2D risk. The proinsulin-raising allele of ARAP1 was associated with a lower fasting glucose (P = 1.7 × 10(-4)), improved β-cell function (P = 1.1 × 10(-5)), and lower risk of T2D (odds ratio 0.88; P = 7.8 × 10(-6)). Notably, PCSK1 encodes the protein prohormone convertase 1/3, the first enzyme in the insulin processing pathway. A genotype score composed of the nine proinsulin-raising alleles was not associated with coronary disease in two large case-control datasets. CONCLUSIONS: We have identified nine genetic variants associated with fasting proinsulin. Our findings illuminate the biology underlying glucose homeostasis and T2D development in humans and argue against a direct role of proinsulin in coronary artery disease pathogenesis

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

A Systematic Study on the Mesomorphic Behavior of Asymmetrical 1-Alkyl-3-dodecylimidazolium Bromides

To determine the essential parameters for mesophase formation in imidazolium-based ionic liquids (ILs), a library of 1-alkyl-3-dodecylimidazolium bromides was synthesized, abbreviated as CnC12, where 0 ≤ n ≤ 13, as the general notion is that a dodecyl side chain would guarantee the formation of an ionic liquid crystal (ILC). All salts were fully characterized by NMR spectroscopy and mass spectrometry. Their thermal properties were recorded, and mesophase formation was assessed. An odd–even effect is observed for 5 ≤ n ≤ 10 in the temperatures of melting transitions. While the majority of this series, as expected, formed mesophases, surprisingly compounds C2C12 and C6C12 could not be classified as ILCs, the latter being a room temperature IL, while C2C12 is a crystalline solid with melting point at 37 °C. The single crystal structure of compound 1-ethyl-3-dodecylimidazolium bromide (C2C12) was successfully obtained. Remarkably, the arrangement of imidazolium cores in the structure is very complicated due to multiple nonclassical hydrogen bonds between bromide anions and imidazolium head groups. In this arrangement, neighboring imidazolium rings are forced by hydrogen bonds to form a “face-to-face” conformation. This seems to be responsible for the elimination of a mesophase. To conclude, the general view of a dodecyl chain being a functional group to generate a mesophase is not entirely valid.Reprinted with permission from Cryst. Growth Des., 2014, 14 (4), pp 1561–1571. Copyright 2014 American Chemical Society.</p

On the Mesophase Formation of 1,3-Dialkylimidazolium Ionic Liquids

A series of seven different 1,3-dialkylimidazolium-based ion-pair salts with the same molecular weight and size but different symmetries was synthesized. For all salts, bromide was chosen as the counterion, giving the series ([C<i>n</i>IMC<i>m</i>]­[Br]), where IM = imidazolium and C<i>n</i> and C<i>m</i> are varying <i>N</i>-alkyl substituents with <i>n</i> + <i>m</i> = 13. Thus, the effect of symmetry on the physicochemical properties, such as thermal transitions, densities and viscosities and particularly mesophase formation, is investigated herein. All salts are fully characterized by NMR spectroscopy and mass spectrometry, and their physicochemical properties such as thermal transitions, densities, and viscosities are reported. Single crystal X-ray structure analysis is reported for 1-tridecylimidazolium bromide ([C0IMC13]­[Br]) and 1-ethyl-3-undecylimidazolium bromide ([C2IMC11]­[Br]). Salts 1-tridecylimidazolium bromide ([C0IMC13]­[Br]) and 1-dodecyl-3-methylimidazolium bromide ([C1IMC12]­[Br]) exhibit thermotropic liquid crystal behavior, confirmed by differential scanning calorimetry, polarized optical microscopy, and small-angle X-ray diffraction to be the SmA mesophase. A structure with interdigitation of alkyl chains is observed for all of [C0IMC13]­[Br], [C1IMC12]­[Br], and [C2IMC11]­[Br], despite the absence of thermotropic liquid crystalline behavior for the latter (and all other isomers with an alkyl chain length less than 12 carbon atoms). This allows us to draw the conclusion that for the liquid crystal phase of an ionic liquid to exist, not only are the calamitic shape and integral length of a molecule important but a minimal alkyl chain length of <i>n</i> = 12 is also required. Therefore, a dodecyl group could be considered as the functional group responsible for liquid crystalline behavior