Control over the circular polarization of emitted light is important for advanced photonic applications, but organic emitters often show weak intrinsic chiroptical responses, limiting their technological application. In this work, we combine chiral molecular design with cholesteric liquid crystal self-assembly to achieve photonic modulation of circularly polarized emission. Bis-BINOL-based chiral dopants displaying intrinsic molecular CPL in solution were synthesized and subsequently employed as highly effective chiral dopants in liquid crystalline hosts (E7) to form chiral nematic phases (N*-LCs) with high twisting power (HTP). The resulting helical superstructures allow precise alignment of the cholesteric reflection band with the emission spectrum, resulting in strong apparent luminescence dissymmetry factor (glum) at low dopant concentrations. Importantly, the doped N*-LCs remain compatible with achiral fluorophores, enabling ternary emissive systems without compromising the helical organization of the host, thereby extending the applicability of these high-HTP bis-BINOL dopants as versatile chiral photonic platforms.

Achieving persistent room-temperature phosphorescence (RTP) in purely organic, heavy atom-free molecules is challenging due to intrinsically weak spin-orbit coupling and the occurrence of non-radiative decay. Here, we investigate a donor-acceptor naphthalonitrile derivative (NMe 2) that combines a pronounced charge-transfer (CT) character with a small singlet-triplet energy gap (Delta E ST), enabling efficient intersystem crossing (ISC), reverse intersystem crossing (RISC), and dual TADF/RTP emission. Comprehensive photophysical measurements reveal strong solvatochromism in solution and the emergence of temperature-dependent delayed emission in rigid matrices. In glassy 2Me-THF, polymethyl methacrylate (PMMA) films, and polymeric 3D-printed objects, NMe 2 exhibits long-lived phosphorescence with lifetimes in the millisecond-to-second range, facilitated by restricted molecular motion and reduced dioxygen quenching. Time-gated and transient photoluminescence studies suggest the coexistence of TADF and phosphorescence in PMMA, with phosphorescence dominating at low temperature. TDDFT calculations support the experimental observations, showing CT-dominated excited states, small Delta E ST values, and mixed singlet-triplet character that promotes efficient ISC. These results highlight the potential of simple donor-acceptor scaffolds as versatile emitters for the development of heavy-atom-free luminescent materials for advanced photonic and optoelectronic applications.

3D-printed porous TiO2/BiFeO3 nanocomposite monoliths with surface areas of up to 65 m2 g-1 were fabricated via two ways employing 3D printing. In method A, BiFeO3 nanoparticles were directly embedded into a TiO2-based hybrid ink for the direct ink writing (DIW) technique, while in method B, BiFeO3 nanoparticles were deposited as a surface coating onto a 3D-printed TiO2 scaffold. The obtained materials were comprehensively characterized by X-ray diffraction (XRD), electron microscopy (SEM, TEM), nitrogen adsorption-desorption, UV-vis spectroscopy, photoluminescence spectroscopy, and X-ray photoelectron spectroscopy (XPS). The photocatalytic performance of the materials was evaluated for the degradation of acyclovir under three different irradiation conditions: a medium-pressure Hg lamp (emission mostly in the UV region, 150 W) and blue LED sources at 420 nm (6 W) and 440 nm (40 W). The sample prepared by method A, including 1 wt % BiFeO3 inside a TiO2 matrix, showed the best performance under all irradiation conditions, which could be attributed to the combination of high surface area and the improved charge separation across the heterojunction interface. Additionally, Density Functional Theory (DFT) calculations were performed to confirm the formation of type-II heterojunctions between BiFeO3 embedded in TiO2 materials, consistent with the experimentally observed enhancement. These 3D-printed materials represent a significant advancement toward the development of photocatalytic water treatment under visible light conditions.

Photoresponsive molecular systems uniting light-controlled switching and luminescence are of great interest for next-generation optoelectronic materials. However, azoarenes in which both photoisomerization and emission are triggered and modulated under a single wavelength remain exceedingly rare. To address these challenges, arylazopyrazoles were combined with heteropentacene luminophores to yield fluorescent photoswitches. In-depth investigations were conducted to understand the concurrent photoluminescence and isomerization in solution, including temperature-dependent NMR studies, measurements of absolute photoluminescence quantum yields, and excited-state lifetimes. The findings were supported by quantum chemical calculations of the excited-state processes, which revealed the interplay between emissive and isomerization pathways, leading to a design concept for fluorescent photoswitches based on arylazopyrazoles. Finally, the application of these multi-responsive emitters was examined by embedding them into liquid crystalline and 3D-printed materials to investigate the effects of temperature, photoswitching, and order on photoluminescence - a pathway to next-generation photoresponsive materials.

A powerful platform for smart materials with adaptive surfaces enabling the post-processing tuning of the physical and mechanical properties is reported. More specifically, 3D-printed materials featuring dynamic covalent bonds at their surfaces are developed and tested with respect to their potential for dynamic property tuning. The integration of acrylates bearing amine groups into tailor-made resins enables post-printing modification of the surface by employing imine condensation or imine exchange reactions. This approach allowed the dynamic tuning of the surface polarity and fluorescence behavior of the 3D-printed objects. Furthermore, the application potential of this concept with respect to self-healable materials was demonstrated by employing the imine condensation reaction for dynamic-covalent welding.

The development of responsive molecules enables the design of novel smart materials for numerous applications. A series of new arylazopyrazoles is designed as dopants for commercially available liquid crystal hosts and their photoresponse in solution and mesophases is investigated. Furthermore, the solid-state structure in single-crystal diffraction is analyzed to gain insight into possible intermolecular interactions of the photoswitches with LC host materials, thus anticipating the effect of photoswitching in the LC phase. Additionally, 3,5-difluorophenol is implemented as a hydrogen-bond donor to tune the impact of the photoisomers on the mesogenic behavior. Unprecedented, reversible control of the distribution of E- and Z-isomers at the photostationary state of different wavelengths (365, 460, and 520nm) is utilized to induce phase transitions of liquid crystals. This strategy allows for the controlled transition between smectic, nematic, and isotropic phases at isothermic conditions by irradiation with the corresponding wavelength - a new concept in the design of photoresponsive materials.

Ultrasmall gold nanoparticles (2 nm) were surface-coated with photoswitchable 3-azopyridine ligands by ligand exchange with n-dodecanethiol-stabilized gold nanoparticles. Each gold nanoparticle carried about 66 dodecanethiol (DDT) ligands and 49 azo ligands. The azo ligands were reversibly switchable between the stable E- and the metastable Z-isomer by UV and green light irradiation as shown by UV-Vis and NMR spectroscopy. The photoswitching was not significantly affected by the conjugation of the azo ligand to the nanoparticle surface, despite the high density of ligands on the particle surface. This offers a pathway for photoswitchable systems on the nanoscale, for example, to manipulate supramolecular systems. The introduction of 0.5 wt% of the nanoparticles into a liquid crystalline host yielded a photoresponsive material which showed a reversible nematic-to-isotropic phase transition upon irradiation.

The unique combination of two classes of luminophores, showing either aggregation-induced or aggregation-caused quenching within a liquid crystal yielded a thermo-sensor with a temperature induced emission shift from green to red.

Discovering the versatile ability of environment-independent solution and solid-state emission (SSSE) enabled new possibilities of fine-tuning photophysical properties, targeting specific organelles, or developing remarkable materials. Herein, we report an unprecedented design concept for SSSE by employing the "magic methyl" effect in a series of alkylated heteropentacyclic luminophores R8, Y8, and G8. Implementing an increasing amount of ortho-methyl groups influences the vertical electronic transitions, tuning the emission colors from red over yellow to green and inverting the preferred state of luminescence from solution to solely the solid-state or even both. An in-depth analysis was performed using X-ray diffractometric structure elucidation, packing analysis and density functional theory calculations to correlate the photophysical properties with the steric pressure induced by the methyl groups. Additionally, the application scope of these new materials was investigated. Mesoporous silica nanoparticles loaded with the three new luminophores were prepared and employed as additives for 3D printing using digital light processing. Ultimately, these stimuli-responsive molecules performed as optical sensors of microenvironmental temperature and phase transition changes in liquid crystals.

Efficient synthesis of extended pi-conjugated systems containing sulphur-rich aromatics is of special interest for organic electronics. Herein, we report the synthesis of new pi-conjugated 5,5 '-diphenyl-2,2 '-bithiophene-based tricatenars. The materials have the same aromatic backbone ending at one terminus with a 3,5-diheptyloxy substituted-benzene ring and a single hexyloxy chain at the other end. They differ from each other in the halogen substitution pattern used at the single alkylated end, where fluorine at different positions was used. The fluorine atom was also replaced by chlorine or bromine atoms to investigate the effect of different types of halogen substituents on the phase behaviour. The molecular self-assembly of the materials was investigated using differential scanning calorimetry, polarized optical microscopy, X-ray diffraction and fluorescence techniques. Depending on the type and position of the halogen substituent, different types of mesophases were observed, including nematic, smectic, and chiral isotropic liquid phase (Iso(1)[*]) and achiral double-gyroid bicontinuous cubic phases with a double helical network structure and Ia (3) over bard symmetry. In particular, the steric effect of halogen substituents adapts two different molecular packing for the cubic phase with local helicity and short-range order, respectively. All materials are fluorescent active, and their fluorescence behaviour could be altered by the type and position of the halogen substituent. Thus, this report provides new functional materials, which could be of interest for optoelectronic applications.

Given current social and ecological challenges such as climate change, energy supply, and e-mobility, the training of future generations of chemists will play a key role in preparing them for future demands and enabling them to develop innovative solutions for current and future problems. However, given the persistent perception of chemistry courses as challenging, the largely consistent high dropout rates in these courses, and the increasing demand for well-trained chemistry graduates, it seems necessary to pursue more coordinated research efforts to support students' chemistry learning at the university level and to increase the professionalization of instructors to improve the quality of teaching. In this communication, we outline the aims of a research network funded by the German Research Foundation and the growing need for increased collaborative research activities in higher education in the field of academic chemistry training as a blueprint for others in the community. We outline our objectives along four topics to address structured and systematic research efforts in organic chemistry education and teaching at the university level. A focus is placed on organic chemistry, as this discipline can provide a clear subject-specific lens but also allows a systemic perspective, which can serve as a model for other areas of chemistry and other natural sciences at universities.

In this contribution, we explored the photocyclization of thioethers to highly substituted dibenzothiophenes (DBT) using solely UV-light without any need for additives. This cost-effective, robust and environmentally friendly approach yielded phosphorescent compounds, which were characterized by X-ray crystallography and state-of-the-art photophysical methods. The resulting DBTs feature ultralong photoluminescence lifetimes and quantum yields close to unity in frozen glassy matrices. The reaction mechanism was elucidated in detail through a combination of quantum chemical calculations and experimental results, providing evidence that triplet states are involved in the cyclization process. Additionally, the photoreaction can also be induced within materials. For this purpose, the precursors were integrated into polymer films or polymer resins suitable for 3D printing. Irradiation of these polymeric objects allows motifs with ultralong phosphorescence to be irreversibly inscribed through the proceeding photocyclization. The in situ photogeneration of DBTs from aromatic thioethers overcomes the observed incompatibilities regarding solubility in polymer resins for 3D printing.

AbstractEin Forschungsnetzwerk bringt Lehrende und Wissenschaftler:innen aus Organik und Fachdidaktik zusammen. Es konzentriert sich auf die Hochschullehre und will basierend auf Best‐PracticeErfahrungen und empirischen Erkenntnissen der Lehr‐Lernforschung Empfehlungen erarbeiten, wie Lehre gestaltet werden sollte.

In this study, we present the synthesis and a versatile way to incorporate photoresponsive organic luminophores into polymeric materials using mesoporous silica nanoparticles (MSNs). The encapsulated thioethers within the MSNs were employed in polyvinyl alcohol (PVA) films, resin-based stereolithography, and electrospinning. Due to light-induced cyclisation to dibenzothiophenes (DBTs), mmOC12 loaded materials were used to inscribe images using UV light. The DBTs formed from mmOC12 (mmDBTA/B) exhibit a long phosphorescence afterglow, which was investigated by steady-state and time-resolved photoluminescence spectroscopy. In addition, scanning electron microscopy (SEM) imaging, including energy dispersive X-ray spectroscopy (EDX), revealed the well-dispersed and intact MSNs in the polymeric materials. This approach shows a general way to incorporate non-polar organic luminophores into polymeric materials while retaining their unique emission properties.

A convincing e-learning system for higher education should offer adequate usability and not add unnecessary (extraneous) cognitive load. It should allow teachers to switch easily from traditional teaching to flipped classrooms to provide students with more opportunities to learn and receive immediate feedback. However, an efficient e-learning and technology-enhanced assessment tool that allows generating digital organic chemistry tasks is yet to be created. The Universities of Bonn and Duisburg-Essen are currently developing and evaluating an e-learning and technology-enhanced assessment tool for organic chemistry. This study compares the effectiveness of traditional paper-pencil-based and digital molecule-drawing tasks in terms of student performance, cognitive load, and usability—factors that all contribute to learning outcomes. Rasch analysis, t-tests, and correlation analyses were used for evaluation, revealing that the developed system can generate digital organic chemistry tasks. Students performed equally well on simple digital and paper-pencil molecule-drawing tasks when they received an appropriate introduction to the digital tool. However, using the digital tool in two of three studies imposes a higher extraneous cognitive load than using paper and pencil. Nevertheless, the students rated the tool as sufficiently usable. A significant negative correlation between extraneous load and tool usability was found, suggesting room for improvement. We are currently concentrating on augmenting the functionality of the new e-learning tool to increase its potential for automatic feedback, even for complex tasks such as reaction mechanisms.

AbstractTwo series with three Pt(II) complexes each (PtLPh‐n, PtLFpy‐n) bearing asymmetric tetradentate ligands as dianionic luminophores with variable alkyl chain lengths were synthesized. Hence, each ligand series is distinguished by one of its cyclometallating rings (phenyl vs. 2,6‐difluoropyrid‐3‐yl). Steady‐state and time‐resolved photoluminescence spectroscopic studies in diluted solutions at room temperature and in glassy matrices at 77 K show that the emissive state is mainly centered on the invariantly electron‐rich cyclometalated side while the second ring regulates the admixture of ligand‐centered and metal‐to‐ligand charge‐transfer character. Hence, the radiative rates can be controlled, as indicated by quantum‐mechanical calculations, which also explain the temperature‐dependent trend in the phosphorescence rate constants. Studies in condensed phases (single‐crystal X‐ray diffractometry, polarized optical microscopy, differential scanning calorimetry, steady‐state and time‐resolved photoluminescence micro(spectro)scopy) showed the development of a smectic A mesophase for the fluorinated species bearing the two longest alkyl chains. Nuclear magnetic resonance‐based studies on the thermodynamics of aggregation in solution confirm the marked enthalpic stabilization of aggregates mediated by the polar 2,6‐difluoropyrid‐3‐yl moiety (and to a lesser extent by dispersive forces between the alkyl chains). On the other hand, the negative entropy of aggregation is dominated by the restriction of degrees of freedom involving the peripheral alkyl moieties upon stacking, which becomes increasingly relevant for longer chains. All these factors control Pt···Pt coupling, a crucial interaction for the design of photofunctional mesogens based on Pt(II) complexes.

The ability to draw molecules based on a given IUPAC name is a fundamental skill in organic chemistry. University students need to acquire appropriate and automated cognitive schemata to master drawing molecules before they can be considered to meaningfully be introduced to face up to reaction equations, cascades, or mechanisms. Similar to experts in organic chemistry, organic chemistry books and digital drawing tools predominantly use skeletal formulas to communicate about organic chemistry. Students must acquire the ability to use this specific representation type as part of their professional development. The present study investigates (1) which representation form beginners in organic chemistry use to draw molecules when they can choose, (2) whether errors between a paper-pencil format (free choice of representation form) and digital format (skeletal formula requested) differ, and (3) to which extent answer correctness and occurrence of error types change when a student's preferred representation form is not available. For this investigation, a within subject design is used. The results show that the skeletal formula is used when it is automatically suggested (in the digital format) but that alternative formulas are drawn when a representation form is freely chosen (in the paper-pencil format). Violations of the octet rule appear less frequently for digital molecule-drawing tasks, but missing answers are more prominent.

AbstractUnter anderem das hat die Organik im letzten Jahr bewegt: milde Oxidation mit Elektrochemie, Oxidation zu enantiomerenreinen Sulfonylverbindungen, Flüssigkristallphasen erkennen mit maschinellem Lernen, CO2reagiert zu Succinat und Carbamaten, eine Alternative zu Bisphenol A, Subporphyrine, photoschaltbare Spinmaterialien, photochemische Thiophen‐Ringerweiterung, und Peptide werden mit Bor versehen und cyclisiert. Die Zusammenstellung des Trendberichts koordiniert hat Martin Breugst, Universität Chemnitz.

AbstractLoss-of-function mutations in the homotrimeric serine protease HTRA1 cause cerebral vasculopathy. Here, we establish independent approaches to achieve the functional correction of trimer assembly defects. Focusing on the prototypical R274Q mutation, we identify an HTRA1 variant that promotes trimer formation thus restoring enzymatic activity in vitro. Genetic experiments in Htra1R274Q mice further demonstrate that expression of this protein-based corrector in trans is sufficient to stabilize HtrA1-R274Q and restore the proteomic signature of the brain vasculature. An alternative approach employs supramolecular chemical ligands that shift the monomer-trimer equilibrium towards proteolytically active trimers. Moreover, we identify a peptidic ligand that activates HTRA1 monomers. Our findings open perspectives for tailored protein repair strategies.

Polystyrolproben werden mit Eisen(III)chlorid und weißen LEDs zu Oligomeren und Benzoylprodukten; ein Wolframatkatalysator invertiert die Absolutkonfiguration an sp 3 ‐Kohlenstoffzentren; gelöstes Rätsel um eine symmetrieverbotene konrotatorische 14‐Elektronen‐Elektrocyclisierung; Polycarbonate, die sich ohne Lösungsmittel recyceln lassen: Highlights von Oktober 2021 bis 2022.