Eldorado - Repositorium der TU Dortmund

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Bei diesem Service handelt es sich um das Institutionelle Repositorium der Technischen Universität Dortmund. Hier werden Ressourcen aus und für Lehre, Studium und Forschung gespeichert, erschlossen und der Öffentlichkeit zugänglich gemacht.

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Fach- und Universitätsübergreifendes 1319
Fakultäten 13791
Graduate School und Graduiertenkollegs 12
Hochschulverwaltung 1246
Sonderforschungsbereiche 1592

Aktuellste Veröffentlichungen

A [2.2]isoindolinophanyl-based carbene (iPC) ligand: synthesis, electronic and photophysical properties, and application in photocatalysis
(2024-07-04) Maity, Sabyasachi; Muthig, André Martin Thomas; Sen, Indranil; Mrózek, Ondřej; Belyaev, Andrey; Hupp, Benjamin; Steffen, Andreas
Cyclic amino(alkyl) and cyclic amino(aryl) carbenes (cAACs/cAArCs) have been established as very useful ligands for catalytic and photonic applications of transition metal complexes. Herein, we describe the synthesis of a structurally related sterically demanding, electrophilic [2.2]isoindolinophanyl-based carbene (iPC) that bears a [2.2]paracyclophane moiety. The latter leads to more delocalized frontier orbitals and intense green fluorescence of (HiPC)OTf (2) from an intra-ligand charge transfer (1ILCT) state in the solid state. Base-promoted synthesis of the free carbene led to an unusual ring expansion and subsequent dimerization reaction, but the beneficial ligand properties can be exploited by trapping in situ at a metal center. The iPC ligand is a very potent π-chromophore, which participates in low energy metal-to-ligand (ML)CT transitions in [RhCl(CO)2(iPC)] (4) and IL-“through-space”-CT transitions in [Au(iPC)2]OTf (5). The steric demand of the iPC leads to high stability of 5 against air, moisture, or solvent attack, and ultralong-lived green phosphorescence with a lifetime of 185 μs is observed in solution. The beneficial photophysical and electronic properties of the iPC ligand, including a large accessible π surface area, were exploited by employing highly efficient energy transfer (EnT) photocatalysis in a [2+2] styrene cycloaddition reaction using 5, which outperformed other established photocatalysts in comparison.
Amtliche Mitteilungen der Technischen Universität Dortmund Nr. 12/2026
(Technische Universität Dortmund, 2026-05-18)
Orientation-dependent stress evolution in diamond abrasive grains under directional loading
(2026-04-29) Brune, Gabriel; Tsagkir Dereli, Tountzer; Olschewski, Lars; Lopes Dias, Nelson Filipe; Kipp, Monika; Biermann, Dirk; Debus, Jörg
Understanding the response of diamond abrasive grains to mechanical loading remains crucial for optimizing their performance in precision manufacturing. In that context, the role of the initial residual stress and crystallographic orientation of the grains is poorly understood. We investigate synthetic diamond grains in two different grit sizes (D126, D252) subjected to directional loading up to 100 N using x-ray diffraction and spatially resolved Raman spectroscopy. Small grains with preferential (111) orientation show an unexpected stress evolution under contact pressures up to 16 GPa, with Raman shifts increasing from 1331.3 to 1333.0cm−1, indicating an enhanced local compressive stress state at the probed surface regions. Conversely, large (311)-oriented grains exhibit a heterogeneous stress development with Raman shifts varying from 1331.5 to 1332.6cm−1, including regions that become more tensile (or less compressive) relative to their initial state. The relationship between the relative Raman shift and a spatially weighted contact pressure follows an empirical power law 𝛿⁢𝐸∝𝑝′𝛼c with opposite, orientation-dependent exponents: 𝛼≈+0.25 for (111) grains showing progressive compression enhancement and 𝛼≈−0.35 for (311) grains exhibiting a trend toward tensile stress components with increasing load. Molecular dynamics simulations reveal that the Schmid factor governs this orientation-dependent response: The low Schmid factor (0.27) for [111] loading restricts dislocation glide, leading to stress retention with high elastic recovery, while the high Schmid factor (0.45) for [311] loading facilitates plastic flow and stress relaxation despite lower peak stress. These findings demonstrate that stress evolution in diamond under directional loading is controlled by the geometric relationship between loading direction and slip systems, providing mechanistic insights for diamond tool design.
From light pulses to selective enhancement: performance analysis of event-based object detection under pulsed automotive headlight illumination
(2026-04-22) Haensel, Leonard; Bertram, Torsten
Pulse-width-modulated (PWM) automotive headlights enhance nighttime event-based camera detection, yet systematic parameter optimization for vulnerable road user detection remains unexplored. This study evaluates PWM frequency, duty cycle, light distribution, ego-vehicle speed, and ambient lighting under European New Car Assessment Programme-inspired crossing scenarios for cyclist and pedestrian detection. Results establish performance ranging from substantial improvements to severe degradation relative to continuous illumination. Cyclist detection achieves robust performance with high-frequency modulation across light distributions, while low-frequency operation with low beam produces severe degradation through background noise accumulation. Pedestrian detection requires high beam with street lighting enabled; low beam universally fails regardless of modulation parameters. Limited parameter combinations achieve simultaneous improvements for both targets. Detection performs optimally on retroreflective surfaces, while low-reflectivity clothing limits capability, requiring target-specific optimization.
From open containers to confined supramolecular architectures
(2026) Ocklenburg, David; Craen, David van; Henke, Sebastian
The work will investigate the preparation and characterization of charge-neutral Zn(II) metal organic cages based on bis(bidentate) hydroxyquinolate ligands, with focus on how ligand topology and functionality modulate anion recognition and guest-directed assembly. Building on a charge-neutral [Zn2L2] host-complex presented by our group in 2022, various rational designed ligands were synthesized and self-assembled with Zn(OAc)2 to yield discrete [Zn2L2] architectures and others. The first chapter will introduce three new bis(bidentate) ligands LmN3-H2, LN3-H2 and Lcrown3-H2 which are designed and synthesized to increase the functionality of the parent [Zn2L2] cage. Spectroscopic and computational analysis indicate that expanded π-surfaces preserve the metal organic cages integrity while enabling additional host-guest π-interactions, and a crown-ether functionalized derivative demonstrates heteroditopic ion-pair binding. Second, to address the challenge that strongly chelating oxalate can disrupt metal-ligand assemblies, a more flexible ligand LDB3-H2 was designed and synthesized to afford a robust charge-neutral [Zn2LDB32] host-complex. This container forms a well-defined 1:1 oxalate host-guest complex in solution. UV/Vis titrations quantify binding and competition experiments demonstrate selective oxalate recognition over longer dicarboxylates and monocarboxylates. Dicarboxylates form host-guest complexes in a slow-guest exchange behavior, whereas mono-carboxylates demonstrate fast-exchange. Finally, a tripodal bis(bidentate) ligand, LTP3-H3, enables guest-induced control over nuclearity and topology. Tricarboxylates template direct formation of trinuclear and hexanuclear onion-type host-guest complexes with architecturally appealing supramolecular features. 1H NMR competition experiments reveal observable interconversion of a trinuclear species into a hexanuclear species and give insight into the respective binding affinities. Kinetic studies suggest an associative-dissociative exchange-transformation mechanism with a substantial activation barrier.