1,1′-(Ethane-1,2-di­yl)bis­(1,4,7-triazonane)

In the centrosymmetric title compound (dtne), C14H32N6, two 1,4,7-triaza­cyclo­nonane (tacn, or 1,4,7-triazonane) moieties are linked together each at an amino position by a single ethyl­ene spacer. The mol­ecular packing is supported by pairs of inter­molecular N—H⋯N hydrogen bonds, which form R 2 2(22) ring motifs and link the mol­ecules into infinite chains running parallel to the a axis

Edge Transfer Lithography Using Alkanethiol Inks

Edge lithographic patterning techniques are based on the utilization of the edges of micrometer-sized template features for the reproduction of submicrometer structures. Edge transfer lithography (ETL) permits local surface modification in a single step by depositing self-assembled monolayers onto a metal substrate selectively along the feature edges of an elastomeric stamp. In this report two stamp designs are described that now allow for the use of alkanethiol inks in ETL and their use as etch resists to reproduce submicrometer structures in gold. Anisotropically modified stamps are shown to combine the potential for very high-resolution patterning with the versatility and simplicity of microcontact printing

Coordination chemistry of amide-functionalised tetraazamacrocycles: structural, relaxometric and cytotoxicity studies

Three different tetraazamacrocyclic ligands containing four amide substituents that feature groups (namely allyl, styryl and propargyl groups) suitable for polymerisation have been synthesised. Gadolinium(III) complexes of these three ligands have been prepared as potential monomers for the synthesis of polymeric MRI contrast agents. To assess the potential of these monomers as MRI contrast agents, their relaxation enhancement properties and cytotoxicity have been determined. A europium(III) complex of one of these ligands (with propargyl substituents) is also presented together with its PARACEST properties. In addition, to gain further insight into the coordination chemistry of the tetra-propargyl substituted ligand, the corresponding zinc(II) and cadmium(II) complexes have been prepared. The X-ray crystal structures of the tetra-propargyl ligand and its corresponding gadolinium(III), zinc(II) and cadmium(II) complexes are also presented

Luminescent iridium complexes for detection of molybdate

Reactions of [Ir(CŸN)2Cl]2 [HCŸN = 2-(3-R-phenyl)pyridine, 2-(3-R-phenylpyrazole) R = H, Me] with Me2-phencat give luminescent complexes [Ir(CŸN)2(Me2-phencat)][PF6] (Me2-2a, b, c)[PF6]. Deprotection of the methoxy groups with BBr3 is problematic as simultaneous bromination of the cyclometallated phenyl groups occurs. However, deprotection of Me2-phencat with BBr3 followed by complexation with [Ir(CŸN)2Cl]2 gives luminescent complexes [Ir(CŸN)2(H2-phencat)][PF6] (H2-3a, c)[PF6], which are luminescent sensors for molybdate

PEG-capped, lanthanide doped GdF3 nanoparticles: luminescent and T-2 contrast agents for optical and MRI multimodal imaging

A facile method for the synthesis of water dispersible Er3+/Yb3+ and Tm3+/Yb3+ doped upconverting GdF3 nanoparticles is reported. Strong upconversion emissions are observed in the red (for Er/Yb doped) and near-infrared (for Tm/Yb doped) regions upon laser excitation at 980 nm. The PEG coating ensures a good dispersion of the system in water and reduces the radiationless de-excitation of the excited states of the Er3+ and Tm3+ ions by water molecules. The r(2) relaxivity values are quite high with respect to the common T-2-relaxing agents (22.6 +/- 3.4 mM(-1) s(-1) and 15.8 +/- 3.4 mM(-1) s(-1) for the Tm/Yb and Er/Yb doped samples, respectively), suggesting that the present NPs can be interesting as T-2 weighted contrast agents for proton MRI purpose. Preliminary experiments conducted in vitro, in stem cell cultures, and in vivo, after subcutaneous injection of the lanthanide-doped GdF3 NPs, indicate scarce toxic effects. After an intravenous injection in mice, the GdF3 NPs localize mainly in the liver. The present results indicate that the present Er3+/Yb3+ and Tm3+/Yb3+ doped GdF3 NPs are suitable candidates to be efficiently used as bimodal probes for both in vitro and in vivo optical and magnetic resonance imaging

Zentrale Rechtsfragen des Bauvergaberechts : ein Vergleich zwischen Deutschland und Österreich

Die vorliegende Ausarbeitung „Zentrale Rechtsfragen des Bauvergaberechts – Ein Vergleich zwischen Deutschland und Österreich –“ befasst sich nicht nur mit rein theoretischen Aspekten des öffentlichen Vergaberechts für Bauleistungen zweier wichtiger europäischer Länder, sondern zeichnet sich vor allem durch eine fundierte, praxisorientierte Darstellung und kompetente Aufarbeitung der schwierigen Rechtsmaterie aus

Flipped Lab Ein verdrehtes Laborpraktikum

Erstsemesterstudierende fühlen sich gerade in der Studieneingangsphase naturwissenschaftlich-technischer Studiengänge häufig kognitiv überfordert, was sich negativ auf die erreichten Lernergebnisse auswirkt. In chemischen Studiengängen zeigt sich dies besonders deutlich in den Einführungspraktika in die Laborarbeit. An einem Praxisbeispiel wird in diesem Beitrag das Flipped-Lab-Konzept vorgestellt, das sich als geeignet erwiesen hat, dieses Lernhindernis zu überwinden. Durch einen Transfer der Prinzipien des Flipped-Classroom-Modells auf eine laborpraktische Lehrveranstaltung, kombiniert mit Online und Gruppenarbeitselementen, gelang es, Vorbereitung und Qualität der praktischen Arbeit und der laborpraktischen Lernergebnisse insgesamt zu verbessern. Die eingesetzten digitalen Werkzeuge wirkten sich positiv auf die subjektive Lernerfahrung sowie die real genutzte Selbststudienzeit der Studierenden aus. (DIPF/Orig.