@article{StojanovićŽidovTravkovaetal.2021, author = {Stojanović, Ivan and Židov, Bruno and Travkova, Oksana and Grigoriev, Dmitry}, title = {Enhanced protective performance of waterborne, microcontainers-doped coatings in harsh environments}, series = {Progress in organic coatings : an international journal}, volume = {157}, journal = {Progress in organic coatings : an international journal}, publisher = {Elsevier Science}, address = {Amsterdam [u.a.]}, issn = {0300-9440}, doi = {10.1016/j.porgcoat.2021.106273}, pages = {17}, year = {2021}, abstract = {In this study, the corrosion inhibitors Zinc oleate and 8-Hydroxyquinoline were successfully encapsulated using an interfacial polyaddition method. As such they were dispersed at different concentrations within the waterborne coating matrix. The resulting composite coatings were applied to the low carbon steel substrates. Successful synthesis and morphological characteristics of microcontainers loaded with inhibitors were confirmed using various characterization techniques. Scanning electron microscopy, dynamic light scattering, and thermogravimetric measurements are techniques used to define the surface, dimensional, and dispersive characteristics of containers, and the share of encapsulated inhibitors. The release study defined the discharge kinetics of the corrosion inhibitor from the microcontainers dispersed freely in an aqueous medium. Electrochemical impedance spectroscopy was used to determine the anticorrosive performance of the samples continuously exposed to various corrosive environments of salt and humidity chambers and NaCl solution. Special emphasis was placed on adhesion testing and visual observations during the exposure period. Significant improvements have been noted in terms of corrosion resistance, which, however, depend on the type of inhibitor used, the concentration of the containers embedded in the coating matrix and on the characteristics of the corrosive environment.}, language = {en} } @article{GahlautPathakGupta2022, author = {Gahlaut, Shashank K. and Pathak, Anisha and Gupta, Banshi D.}, title = {Recent advances in silver nanostructured substrates for plasmonic sensors}, series = {Biosensors : open access journal}, volume = {12}, journal = {Biosensors : open access journal}, number = {9}, publisher = {MDPI}, address = {Basel}, issn = {2079-6374}, doi = {10.3390/bios12090713}, pages = {37}, year = {2022}, abstract = {Noble metal nanostructures are known to confine photon energies to their dimensions with resonant oscillations of their conduction electrons, leading to the ultrahigh enhancement of electromagnetic fields in numerous spectroscopic methods. Of all the possible plasmonic nanomaterials, silver offers the most intriguing properties, such as best field enhancements and tunable resonances in visible-to-near infrared regions. This review highlights the recent developments in silver nanostructured substrates for plasmonic sensing with the main emphasis on surface plasmon resonance (SPR) and surface-enhanced Raman spectroscopy (SERS) over the past decade. The main focus is on the synthesis of silver nanostructured substrates via physical vapor deposition and chemical synthesis routes and their applications in each sensing regime. A comprehensive review of recent literature on various possible silver nanostructures prepared through these methodologies is discussed and critically reviewed for various planar and optical fiber-based substrates.}, language = {en} } @article{DiehnSchlaadKneipp2022, author = {Diehn, Sabrina Maria and Schlaad, Helmut and Kneipp, Janina}, title = {Multivariate imaging for fast evaluation of in situ dark field microscopy hyperspectral data}, series = {Molecules : a journal of synthetic chemistry and natural product chemistry}, volume = {27}, journal = {Molecules : a journal of synthetic chemistry and natural product chemistry}, number = {16}, publisher = {MDPI}, address = {Basel}, issn = {1420-3049}, doi = {10.3390/molecules27165146}, pages = {15}, year = {2022}, abstract = {Dark field scattering microscopy can create large hyperspectral data sets that contain a wealth of information on the properties and the molecular environment of noble metal nanoparticles. For a quick screening of samples of microscopic dimensions that contain many different types of plasmonic nanostructures, we propose a multivariate analysis of data sets of thousands to several hundreds of thousands of scattering spectra. By using non-negative matrix factorization for decomposing the spectra, components are identified that represent individual plasmon resonances and relative contributions of these resonances to particular microscopic focal volumes in the mapping data sets. Using data from silver and gold nanoparticles in the presence of different molecules, including gold nanoparticle-protein agglomerates or silver nanoparticles forming aggregates in the presence of acrylamide, plasmonic properties are observed that differ from those of the original nanoparticles. For the case of acrylamide, we show that the plasmon resonances of the silver nanoparticles are ideally suited to support surface enhanced Raman scattering (SERS) and the two-photon excited process of surface enhanced hyper Raman scattering (SEHRS). Both vibrational tools give complementary information on the in situ formed polyacrylamide and the molecular composition at the nanoparticle surface.}, language = {en} } @article{TarazonaWeiBrottetal.2022, author = {Tarazona, Natalia A. and Wei, Ren and Brott, Stefan and Pfaff, Lara and Bornscheuer, Uwe T. and Lendlein, Andreas and Machatschek, Rainhard}, title = {Rapid depolymerization of poly(ethylene terephthalate) thin films by a dual-enzyme system and its impact on material properties}, series = {Chem Catalysis}, volume = {2}, journal = {Chem Catalysis}, number = {12}, publisher = {Cell Press}, address = {Cambridge}, issn = {2667-1093}, doi = {10.1016/j.checat.2022.11.004}, pages = {3573 -- 3589}, year = {2022}, abstract = {Enzymatic hydrolysis holds great promise for plastic waste recycling and upcycling. The interfacial catalysis mode, and the variability of polymer specimen properties under different degradation conditions, add to the complexity and difficulty of understanding polymer cleavage and engineering better biocatalysts. We present a systemic approach to studying the enzyme-catalyzed surface erosion of poly(ethylene terephthalate) (PET) while monitoring/controlling operating conditions in real time with simultaneous detection of mass loss and changes in viscoelastic behavior. PET nanofilms placed on water showed a porous morphology and a thicknessdependent glass transition temperature (T-g) between 40 degrees C and 44 degrees C, which is >20 degrees C lower than the T-g of bulk amorphous PET. Hydrolysis by a dual-enzyme system containing thermostabilized variants of Ideonella sakaiensis PETase and MHETase resulted in a maximum depolymerization of 70\% in 1 h at 50 degrees C. We demonstrate that increased accessible surface area, amorphization, and T-g reduction speed up PET degradation while simultaneously lowering the threshold for degradation-induced crystallization.}, language = {en} } @article{RotheZhaoHalimetal.2022, author = {Rothe, Martin and Zhao, Yuhang and Halim, Henry and Lu, Yan and Benson, Oliver}, title = {Spatial mapping of bleaching in a metal-organic plasmon converter}, series = {Optics continuum}, volume = {1}, journal = {Optics continuum}, number = {8}, publisher = {Optica Publishing Group}, address = {Washington}, issn = {2770-0208}, doi = {10.1364/OPTCON.454911}, pages = {1730 -- 1740}, year = {2022}, abstract = {Hybrid nanophotonic elements, fabricated by organic and inorganic materials, are going to be key components of modern devices. Coupled systems of photoemitters with a plasmonic waveguide serve the demand for nanoscopic frequency converters. However, processes like the degradation of the photoemitters via photobleaching occur and need to be monitored and controlled, to realize future successful devices. We introduce a hybrid perylene-diimide / silver nanowire as plasmon frequency converter. A versatile method is presented to monitor and analyze the bleaching process. It is based on a time series of photoluminescence images, during the operation of a single converter. An analytical model is applied on the data and unveils that the photobleaching rate is constant and independent of the operation of the plasmon converter.}, language = {en} } @article{ChemuraSchrumpfGuenteretal.2023, author = {Chemura, Sitshengisiwe and Schrumpf, Tim and G{\"u}nter, Christina and Kumke, Michael Uwe}, title = {Ceria nanomaterials containing ytterbium}, series = {RSC Advances : an international journal to further the chemical sciences}, volume = {13}, journal = {RSC Advances : an international journal to further the chemical sciences}, number = {50}, publisher = {RSC Publishing}, address = {London}, issn = {2046-2069}, doi = {10.1039/D3RA06868D}, pages = {35445 -- 35456}, year = {2023}, abstract = {Lanthanide based ceria nanomaterials are important practical materials due to the redox properties that are useful in the avenues pertaining to technology and life sciences. Sub 10 nm spherical and highly monodisperse Ce1-xYbxO2-y (0.04 ≤ x ≤ 0.22) nanoparticles were synthesized by thermal decomposition, annealed separately at 773 K and 1273 K for 2 hours and characterized. Elemental mapping for Yb3+ doped ceria nanoparticles shows homogeneous distribution of Yb3+ atoms in the ceria with low Yb3+ content annealed at 773 K and 1273 K for 2 hours. However, clusters are observed for 773 K annealed ceria samples with high concentration of Yb3+. These clusters are not detected in 1273 K annealed nanomaterials. Introducing small amounts of Yb3+ ions into the ceria lattice as spectroscopic probes can provide detailed information about the atomic structure and local environments allowing the monitoring of small structural changes, such as clustering. The emission spectra observed at room temperature and at 4 K have a manifold of bands that corresponds to the 2F5/2 → 2F7/2 transition of Yb3+ ions. Some small shifts are observed in the Stark splitting pattern depending on the sample and the annealing conditions. The deconvolution by PARAFAC analysis yielded luminescence decay kinetics as well as the associated luminescence spectra of three species for each of the low Yb3+ doped ceria samples annealed at 773 K and one species for the 1273 K annealed samples. However, the ceria samples with high concentration of Yb3+ annealed at the two temperatures showed only one species with lower decay times as compared to the low Yb3+ doped ceria samples.}, language = {en} } @article{LehnenKurkiHartlieb2022, author = {Lehnen, Anne-Catherine and Kurki, Jan A. M. and Hartlieb, Matthias}, title = {The difference between photo-iniferter and conventional RAFT polymerization}, series = {Polymer Chemistry}, volume = {13}, journal = {Polymer Chemistry}, number = {11}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1759-9954}, doi = {10.1039/d1py01530c}, pages = {1537 -- 1546}, year = {2022}, abstract = {Photo-iniferter (PI)-RAFT polymerization, the direct activation of chain transfer agents via light, is a fascinating polymerization technique, as it overcomes some restriction of conventional RAFT polymerization. As such, we elucidated the role of reversible deactivation in this context using a monomer-CTA pair with low chain transfer capabilities. Tests with varying targeted degrees of polymerization (DP) or monomer concentrations revealed no significant improvement of polymerization control using the PI-process. Control can however be achieved via slow monomer addition, increasing the number of activation/deactivation events per monomer addition. More importantly, the livingness of the polymerization was found to be extraordinarily high, enabling the straightforward and rapid synthesis of multiblock copolymers with up to 20 blocks and a high number of repeating units per block (DP = 25-100) maintaining an overall excellent definition (M-n = 90 300 g mol(-1), D = 1.29). This study highlights the enormous potential of PI-RAFT polymerization for the synthesis of polymeric materials.}, language = {en} } @article{HermannsKunold2022, author = {Hermanns, Jolanda and Kunold, Helen}, title = {Mechanism comics as a task in a written exam in organic chemistry for pre-service chemistry teachers}, series = {Chemistry teacher international : best practices in chemistry education}, volume = {4}, journal = {Chemistry teacher international : best practices in chemistry education}, number = {3}, publisher = {De Gruyter}, address = {Berlin}, issn = {2569-3263}, doi = {10.1515/cti-2021-0035}, pages = {259 -- 269}, year = {2022}, abstract = {In this paper, we describe and evaluate a study on the use of mechanism comics for writing solutions to a task in a written exam for the course "Organic Chemistry I for Pre-Service Chemistry Teachers." The students had to design a reaction mechanism for a reaction that was unknown to them and write captions explaining every step of their reaction mechanism. The students' work was evaluated using the method of qualitative content analysis in four rounds by both authors. The majority of the captions were coded as "descriptive" and only a minority as "causal." This means that the students mostly described "what" happened, but seldom "why" this happened. Implicit electron movement was also described more often than explicit electron movement. The majority of the captions were technically correct. In summary, the students were capable of designing and describing a reaction mechanism for a previously unknown reaction. The quality of their reasoning could be improved, however. In the new course, the quality of students' mechanistic reasoning and then especially their explanations of "why" mechanistic steps occur will be given much clearer emphasis.}, language = {en} } @article{Titov2022, author = {Titov, Evgenii}, title = {Effect of conformational disorder on exciton states of an azobenzene aggregate}, series = {Physical chemistry, chemical physics : a journal of European Chemical Societies}, volume = {24}, journal = {Physical chemistry, chemical physics : a journal of European Chemical Societies}, number = {39}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1463-9076}, doi = {10.1039/d2cp02774g}, pages = {24002 -- 24006}, year = {2022}, abstract = {Azobenzene is a prototypical molecular photoswitch, widely used to trigger a variety of transformations at different length scales. In systems like self-assembled monolayers or micelles, azobenzene chromophores may interact with each other, which gives rise to the emergence of exciton states. Here, using first-principles calculations, we investigate how conformational disorder (induced, e.g., by thermal fluctuations) affects localization of these states, on an example of an H-type azobenzene tetramer. We find that conformational disorder leads to (partial) exciton localization on a single-geometry level, whereas ensemble-averaging results in a delocalized picture. The pi pi* and n pi* excitons at high and low temperatures are discussed.}, language = {en} } @article{SandSchmidt2022, author = {Sand, Patrick and Schmidt, Bernd}, title = {Orthogonal arylation of a diene-sulfonamide using cationic transition metal catalysts}, series = {European journal of organic chemistry}, volume = {2022}, journal = {European journal of organic chemistry}, number = {47}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1434-193X}, doi = {10.1002/ejoc.202201336}, pages = {8}, year = {2022}, abstract = {The regioselectivity of two mechanistically distinct alkenylation reactions catalyzed by in situ-formed cationic transition metal complexes was studied using N-allyl-N-phenylethenesulfonamide as a model compound. Orthogonal selectivity was observed for the Ru-catalyzed C-H-activating alkenylation with acetanilides, which occurs preferentially at the electron deficient double bond, and for a Pd-catalyzed Heck-type coupling with arene diazonium salts, which occurs preferentially at the more electron rich double bond of the N-allyl substituent.}, language = {en} } @article{PruefertBeitzReichetal.2022, author = {Pr{\"u}fert, Christian and Beitz, Toralf and Reich, Olaf and L{\"o}hmannsr{\"o}ben, Hans-Gerd}, title = {Inline process analysis of copper-bearing aerosols using laser-induced breakdown spectroscopy, laser-induced incandescence and optical imaging}, series = {Spectrochimica acta, Part B, Atomic spectroscopy}, volume = {197}, journal = {Spectrochimica acta, Part B, Atomic spectroscopy}, publisher = {Elsevier}, address = {Amsterdam [u.a.]}, issn = {0584-8547}, doi = {10.1016/j.sab.2022.106527}, pages = {11}, year = {2022}, abstract = {The quantification and identification of aerosols in industry plays a key role in process monitoring and control and lays the foundation for process automation aspired by the industry 4.0 initiative. However, measuring particulate matter's mass and number concentrations in harsh environments poses great analytical constraints. The presented approach comprises a comprehensive set of light-and imaging-based techniques, all contactless, in-line, and real-time. It includes, but is not limited to, stroboscopic imaging, laser-induced breakdown spectroscopy (LIBS) and laser-induced incandescence (LII). Stroboscopic imaging confirmed the particles sphericity and was used to measure the particle number density. A phase-selective LIBS setup with low fluence and 500 Hz repetition rate was used to classify each particle with a single-pulse and in real time. Simultaneously, the created plasma was captured by CCD imaging to determine the detection volume and hit rate of the LIBS setup. Both data sets combined were converted to a particle number density, which was consistent with the particle number density of the stroboscopic measurements. Furthermore, using a photodiode and microphone in parallel to the LIBS setup allowed for the photoacoustic normalization of the spectral line intensity at the laser repetition rate of 500 Hz. This was done as a partial photoacoustic normalization method with the cut-off based on the coefficient of variation (CV), reducing it by 25\%. Aside from that photodiode and microphone were proven to be valuable event counting with the advantage of the less spatially constricted. A second laser setup was used for laser -induced incandescence (LII) making it possible to classify the particles based on their incandescence tendency. Given its larger probing volume, LII could be employed at very low particle number densities. With respect to the current literature, this is the first approach of using LII as an in-line, real-time analytical technique for the compositional classification of metal-bearing aerosols.}, language = {en} } @article{WessigBadetkoKoebe2022, author = {Wessig, Pablo and Badetko, Dominik and Koebe, Michael}, title = {Triplet sensitized Photo-Dehydro-Diels-Alder reaction}, series = {ChemistrySelect}, volume = {7}, journal = {ChemistrySelect}, number = {38}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {2365-6549}, doi = {10.1002/slct.202202648}, pages = {6}, year = {2022}, abstract = {We report on the triplet sensitization of the intramolecular Photo-Dehydro-Diels-Alder (PDDA) reaction of two diaryl suberates bearing methyl propiolate chromophors. Compared with the non-sensitized irradiation, considerably increased yields could be observed. Moreover, it is possible to use the more efficient UVA lamps instead of UVB lamps. Among three investigated sensitizers (xanthone, benzophenone, thioxanthone) xanthone gave the best results.}, language = {en} } @article{EbelBald2022, author = {Ebel, Kenny and Bald, Ilko}, title = {Low-energy (5-20 eV) electron-induced single and double strand breaks in well-defined DNA sequences}, series = {Journal of physical chemistry letters}, volume = {13}, journal = {Journal of physical chemistry letters}, number = {22}, publisher = {American Chemical Society}, address = {Washington, DC}, issn = {1948-7185}, doi = {10.1021/acs.jpclett.2c00684}, pages = {4871 -- 4876}, year = {2022}, abstract = {Ionizing radiation is used in cancer radiation therapy to effectively damage the DNA of tumors. The main damage is due to generation of highly reactive secondary species such as low-energy electrons (LEEs). The accurate quantification of DNA radiation damage of well-defined DNA target sequences in terms of absolute cross sections for LEE-induced DNA strand breaks is possible by the DNA origami technique; however, to date, it is possible only for DNA single strands. In the present work DNA double strand breaks in the DNA sequence 5 '-d(CAC)4/5 ' d(GTG)4 are compared with DNA single strand breaks in the oligonucleotides 5 '-d(CAC)4 and 5 '-d(GTG)4 upon irradiation with LEEs in the energy range from 5 to 20 eV. A maximum of strand break cross section was found around 7 and 10 eV independent of the DNA sequence, indicating that dissociative electron attachment is the underlying mechanism of strand breakage and confirming previous studies using plasmid DNA.}, language = {en} } @article{ErlerRiebeBeitzetal.2023, author = {Erler, Alexander and Riebe, Daniel and Beitz, Toralf and L{\"o}hmannsr{\"o}ben, Hans-Gerd and Leenen, Mathias and P{\"a}tzold, Stefan and Ostermann, Markus and W{\´o}jcik, Michał}, title = {Mobile laser-induced breakdown spectroscopy for future application in precision agriculture}, series = {Sensors}, volume = {23}, journal = {Sensors}, number = {16}, publisher = {MDPI}, address = {Basel}, issn = {1424-8220}, doi = {10.3390/s23167178}, pages = {17}, year = {2023}, abstract = {In precision agriculture, the estimation of soil parameters via sensors and the creation of nutrient maps are a prerequisite for farmers to take targeted measures such as spatially resolved fertilization. In this work, 68 soil samples uniformly distributed over a field near Bonn are investigated using laser-induced breakdown spectroscopy (LIBS). These investigations include the determination of the total contents of macro- and micronutrients as well as further soil parameters such as soil pH, soil organic matter (SOM) content, and soil texture. The applied LIBS instruments are a handheld and a platform spectrometer, which potentially allows for the single-point measurement and scanning of whole fields, respectively. Their results are compared with a high-resolution lab spectrometer. The prediction of soil parameters was based on multivariate methods. Different feature selection methods and regression methods like PLS, PCR, SVM, Lasso, and Gaussian processes were tested and compared. While good predictions were obtained for Ca, Mg, P, Mn, Cu, and silt content, excellent predictions were obtained for K, Fe, and clay content. The comparison of the three different spectrometers showed that although the lab spectrometer gives the best results, measurements with both field spectrometers also yield good results. This allows for a method transfer to the in-field measurements.}, language = {en} } @article{AdesinaBlockGuenteretal.2023, author = {Adesina, Morenike O. and Block, Inga and G{\"u}nter, Christina and Unuabonah, Emmanuel Iyayi and Taubert, Andreas}, title = {Efficient Removal of Tetracycline and Bisphenol A from Water with a New Hybrid Clay/TiO2 Composite}, series = {ACS Omega}, volume = {8}, journal = {ACS Omega}, number = {24}, publisher = {American Chemical Society}, address = {Washington}, issn = {2470-1343}, doi = {10.1021/acsomega.3c00184}, pages = {21594 -- 21604}, year = {2023}, abstract = {New TiO2 hybrid composites were prepared fromkaolinclay, predried and carbonized biomass, and titanium tetraisopropoxideand explored for tetracycline (TET) and bisphenol A (BPA) removalfrom water. Overall, the removal rate is 84\% for TET and 51\% for BPA.The maximum adsorption capacities (q (m))are 30 and 23 mg/g for TET and BPA, respectively. These capacitiesare far greater than those obtained for unmodified TiO2. Increasing the ionic strength of the solution does not change theadsorption capacity of the adsorbent. pH changes only slightly changeBPA adsorption, while a pH > 7 significantly reduces the adsorptionof TET on the material. The Brouers-Sotolongo fractal modelbest describes the kinetic data for both TET and BPA adsorption, predictingthat the adsorption process occurs via a complex mechanism involvingvarious forces of attraction. Temkin and Freundlich isotherms, whichbest fit the equilibrium adsorption data for TET and BPA, respectively,suggest that adsorption sites are heterogeneous in nature. Overall,the composite materials are much more effective for TET removal fromaqueous solution than for BPA. This phenomenon is assigned to a differencein the TET/adsorbent interactions vs the BPA/adsorbent interactions:the decisive factor appears to be favorable electrostatic interactionsfor TET yielding a more effective TET removal.}, language = {en} } @article{MazareiPenschkeSaalfrank2023, author = {Mazarei, Elham and Penschke, Christopher and Saalfrank, Peter}, title = {Band gap engineering in two-dimensional materials by functionalization}, series = {ACS Omega}, volume = {8}, journal = {ACS Omega}, number = {24}, publisher = {American Chemical Society}, address = {Washington}, issn = {2470-1343}, doi = {10.1021/acsomega.3c02068}, pages = {22026 -- 22041}, year = {2023}, abstract = {Graphene is well-knownfor its unique combination of electricaland mechanical properties. However, its vanishing band gap limitsthe use of graphene in microelectronics. Covalent functionalizationof graphene has been a common approach to address this critical issueand introduce a band gap. In this Article, we systematically analyzethe functionalization of single-layer graphene (SLG) and bilayer graphene(BLG) with methyl (CH3) using periodic density functionaltheory (DFT) at the PBE+D3 level of theory. We also include a comparisonof methylated single-layer and bilayer graphene, as well as a discussionof different methylation options (radicalic, cationic, and anionic).For SLG, methyl coverages ranging from 1/8 to 1/1, (i.e.,the fully methylated analogue of graphane) are considered. We findthat up to a coverage theta of 1/2, graphene readily accepts CH3, with neighbor CH3 groups preferring trans positions. Above theta = 1/2, the tendency to accept further CH3 weakens and the lattice constant increases. The band gapbehaves less regularly, but overall it increases with increasing methylcoverage. Thus, methylated graphene shows potential for developingband gap-tuned microelectronics devices and may offer further functionalizationoptions. To guide in the interpretation of methylation experiments,vibrational signatures of various species are characterized by normal-modeanalysis (NMA), their vibrational density of states (VDOS), and infrared(IR) spectra, the latter two are obtained from ab initio moleculardynamics (AIMD) in combination with a velocity-velocity autocorrelationfunction (VVAF) approach.}, language = {en} } @article{KleinpeterKoch2023, author = {Kleinpeter, Erich and Koch, Andreas}, title = {The multiple bond character of the carbon-boron bond in boron trapped N-heterocyclic carbenes (NHCs) and cyclic(alkyl)(amino) carbenes (CAACs) on the magnetic criterion}, series = {Tetrahedron}, volume = {140}, journal = {Tetrahedron}, publisher = {Elsevier}, address = {Oxford}, issn = {0040-4020}, doi = {10.1016/j.tet.2023.133469}, pages = {13}, year = {2023}, abstract = {Geometry, 11B, 13C chemical shifts and the spatial magnetic properties (Through-Space NMR Shieldings -TSNMRS) of both cations and anions of boron-trapped N-heterocyclic carbenes (NHCs) and cyclic (alkyl)(amino)carbenes (CAACs) and of the corresponding diborane/diborene/diboryne dis-carbene adducts have been calculated using the GIAO perturbation method employing the nucleus independent chemical shift (NICS) concept; the TSNMRS results are visualized as iso-chemical-shielding surfaces (ICSS) of various size and direction. The ICSS of the TSNMRS (actually the anisotropy effects measurable in 1H NMR spectroscopy) are employed to qualify and quantify the present multiple bond character of the Carbene-Boron bond in the trapped NHCs and CAACs. Results are confirmed by bond length and 11B/13C chemical shift variations. Thus the partial multiple bond character of the Carbene-Boron bond cannot be expressed by the arrow of weak, much longer dative bonds and should be omitted as in other covalent lone pair-it or triel bonds. \& COPY; 2023 Elsevier Ltd. All rights reserved.}, language = {en} } @article{SchlappaBresselReichetal.2023, author = {Schlappa, Stephanie and Bressel, Lena and Reich, Oliver and M{\"u}nzberg, Marvin}, title = {Advanced particle size analysis in high-solid-content polymer dispersions using photon density wave spectroscopy}, series = {Polymers}, volume = {15}, journal = {Polymers}, number = {15}, publisher = {MDPI}, address = {Basel}, issn = {2073-4360}, doi = {10.3390/polym15153181}, pages = {17}, year = {2023}, abstract = {High-solid-content polystyrene and polyvinyl acetate dispersions of polymer particles with a 50 nm to 500 nm mean particle diameter and 12-55\% (w/w) solid content have been produced via emulsion polymerization and characterized regarding their optical and physical properties. Both systems have been analyzed with common particle-size-measuring techniques like dynamic light scattering (DLS) and static light scattering (SLS) and compared to inline particle size distribution (PSD) measurements via photon density wave (PDW) spectroscopy in undiluted samples. It is shown that particle size measurements of undiluted polystyrene dispersions are in good agreement between analysis methods. However, for polyvinyl acetate particles, size determination is challenging due to bound water in the produced polymer. For the first time, water-swelling factors were determined via an iterative approach of PDW spectroscopy error (X-2) minimization. It is shown that water-swollen particles can be analyzed in high-solid-content solutions and their physical properties can be assumed to determine the refractive index, density, and volume fraction in dispersion. It was found that assumed water swelling improved the reduced scattering coefficient fit by PDW spectroscopy by up to ten times and particle size determination was refined and enabled. Particle size analysis of the water-swollen particles agreed well with offline-based state-of-the-art techniques.}, language = {en} } @article{XuDongJieetal.2022, author = {Xu, Yaolin and Dong, Kang and Jie, Yulin and Adelhelm, Philipp and Chen, Yawei and Xu, Liang and Yu, Peiping and Kim, Junghwa and Kochovski, Zdravko and Yu, Zhilong and Li, Wanxia and LeBeau, James and Shao-Horn, Yang and Cao, Ruiguo and Jiao, Shuhong and Cheng, Tao and Manke, Ingo and Lu, Yan}, title = {Promoting mechanistic understanding of lithium deposition and solid-electrolyte interphase (SEI) formation using advanced characterization and simulation methods: recent progress, limitations, and future perspectives}, series = {Avanced energy materials}, volume = {12}, journal = {Avanced energy materials}, number = {19}, publisher = {Wiley}, address = {Weinheim}, issn = {1614-6832}, doi = {10.1002/aenm.202200398}, pages = {22}, year = {2022}, abstract = {In recent years, due to its great promise in boosting the energy density of lithium batteries for future energy storage, research on the Li metal anode, as an alternative to the graphite anode in Li-ion batteries, has gained significant momentum. However, the practical use of Li metal anodes has been plagued by unstable Li (re)deposition and poor cyclability. Although tremendous efforts have been devoted to the stabilization of Li metal anodes, the mechanisms of electrochemical (re-)deposition/dissolution of Li and solid-electrolyte-interphase (SEI) formation remain elusive. This article highlights the recent mechanistic understandings and observations of Li deposition/dissolution and SEI formation achieved from advanced characterization techniques and simulation methods, and discusses major limitations and open questions in these processes. In particular, the authors provide their perspectives on advanced and emerging/potential methods for obtaining new insights into these questions. In addition, they give an outlook into cutting-edge interdisciplinary research topics for Li metal anodes. It pushes beyond the current knowledge and is expected to accelerate development toward a more in-depth and comprehensive understanding, in order to guide future research on Li metal anodes toward practical application.}, language = {en} } @article{RotheZhaoMuelleretal.2021, author = {Rothe, Martin and Zhao, Yuhang and M{\"u}ller, Johannes and Kewes, G{\"u}nter and Koch, Christoph T. and Lu, Yan and Benson, Oliver}, title = {Self-assembly of plasmonic nanoantenna-waveguide structures for subdiffractional chiral sensing}, series = {ACS nano}, volume = {15}, journal = {ACS nano}, number = {1}, publisher = {American Chemical Society}, address = {Washington}, issn = {1936-0851}, doi = {10.1021/acsnano.0c05240}, pages = {351 -- 361}, year = {2021}, abstract = {Spin-momentum locking is a peculiar effect in the near-field of guided optical or plasmonic modes. It can be utilized to map the spinning or handedness of electromagnetic fields onto the propagation direction. This motivates a method to probe the circular dichroism of an illuminated chiral object. In this work, we demonstrate local, subdiffraction limited chiral coupling of light and propagating surface plasmon polaritons in a self-assembled system of a gold nanoantenna and a silver nanowire. A thin silica shell around the nanowire provides precise distance control and also serves as a host for fluorescent molecules, which indicate the direction of plasmon propagation. We characterize our nanoantenna-nanowire systems comprehensively through correlated electron microscopy, energy-dispersive X-ray spectroscopy, dark-field, and fluorescence imaging. Three-dimensional numerical simulations support the experimental findings. Besides our measurement of far-field polarization, we estimate sensing capabilities and derive not only a sensitivity of 1 mdeg for the ellipticity of the light field, but also find 10(3) deg cm(2)/dmol for the circular dichroism of an analyte locally introduced in the hot spot of the antenna-wire system. Thorough modeling of a prototypical design predicts on-chip sensing of chiral analytes. This introduces our system as an ultracompact sensor for chiral response far below the diffraction limit.}, language = {en} }