TY - JOUR A1 - Fischer, Eric Wolfgang A1 - Anders, Janet A1 - Saalfrank, Peter T1 - Cavity-altered thermal isomerization rates and dynamical resonant localization in vibro-polaritonic chemistry JF - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr N2 - It has been experimentally demonstrated that reaction rates for molecules embedded in microfluidic optical cavities are altered when compared to rates observed under "ordinary" reaction conditions. However, precise mechanisms of how strong coupling of an optical cavity mode to molecular vibrations affects the reactivity and how resonance behavior emerges are still under dispute. In the present work, we approach these mechanistic issues from the perspective of a thermal model reaction, the inversion of ammonia along the umbrella mode, in the presence of a single-cavity mode of varying frequency and coupling strength. A topological analysis of the related cavity Born-Oppenheimer potential energy surface in combination with quantum mechanical and transition state theory rate calculations reveals two quantum effects, leading to decelerated reaction rates in qualitative agreement with experiments: the stiffening of quantized modes perpendicular to the reaction path at the transition state, which reduces the number of thermally accessible reaction channels, and the broadening of the barrier region, which attenuates tunneling. We find these two effects to be very robust in a fluctuating environment, causing statistical variations of potential parameters, such as the barrier height. Furthermore, by solving the time-dependent Schrodinger equation in the vibrational strong coupling regime, we identify a resonance behavior, in qualitative agreement with experimental and earlier theoretical work. The latter manifests as reduced reaction probability when the cavity frequency omega(c) is tuned resonant to a molecular reactant frequency. We find this effect to be based on the dynamical localization of the vibro-polaritonic wavepacket in the reactant well. Y1 - 2022 U6 - https://doi.org/10.1063/5.0076434 SN - 0021-9606 SN - 1089-7690 VL - 156 IS - 15 PB - American Institute of Physics CY - Melville, NY ER - TY - JOUR A1 - Reifarth, Martin A1 - Bekir, Marek A1 - Bapolisi, Alain M. A1 - Titov, Evgenii A1 - Nusshardt, Fabian A1 - Nowaczyk, Julius A1 - Grigoriev, Dmitry A1 - Sharma, Anjali A1 - Saalfrank, Peter A1 - Santer, Svetlana A1 - Hartlieb, Matthias A1 - Böker, Alexander T1 - A dual pH- and light-responsive spiropyrane-based surfactant BT - investigations on Its switching behavior and remote control over emulsion stability JF - Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker ; International edition N2 - A cationic surfactant containing a spiropyrane unit is prepared exhibiting a dual-responsive adjustability of its surface-active characteristics. The switching mechanism of the system relies on the reversible conversion of the non-ionic spiropyrane (SP) to a zwitterionic merocyanine (MC) and can be controlled by adjusting the pH value and via light, resulting in a pH-dependent photoactivity: While the compound possesses a pronounced difference in surface activity between both forms under acidic conditions, this behavior is suppressed at a neutral pH level. The underlying switching processes are investigated in detail, and a thermodynamic explanation based on a combination of theoretical and experimental results is provided. This complex stimuli-responsive behavior enables remote-control of colloidal systems. To demonstrate its applicability, the surfactant is utilized for the pH-dependent manipulation of oil-in-water emulsions. KW - Dual-Responsiveness KW - Manipulation of Emulsion Stability KW - Spiropyrane KW - Surfactant KW - Switchable Surfactants KW - pH-Dependent Photoresponsivity Y1 - 2022 U6 - https://doi.org/10.1002/anie.202114687 SN - 1433-7851 SN - 1521-3773 VL - 61 IS - 21 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Picconi, David T1 - Quantum dynamics of the photoinduced charge separation in a symmetric donor-acceptor-donor triad BT - the role of vibronic couplings, symmetry and temperature JF - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr N2 - The photoinduced charge separation in a symmetric donor-acceptor-donor (D-A-D) triad is studied quantum mechanically using a realistic diabatic vibronic coupling model. The model includes a locally excited DA*D state and two charge-transfer states D(+)A(-)D and DA(-)D(+) and is constructed according to a procedure generally applicable to semirigid D-A-D structures and based on energies, forces, and force constants obtained by quantum chemical calculations. In this case, the electronic structure is described by time-dependent density functional theory, and the corrected linear response is used in conjunction with the polarizable continuum model to account for state-specific solvent effects. The multimode dynamics following the photoexcitation to the locally excited state are simulated by the hybrid Gaussian-multiconfigurational time-dependent Hartree method, and temperature effects are included using thermo field theory. The dynamics are connected to the transient absorption spectrum obtained in recent experiments, which is simulated and fully assigned from first principles. It is found that the charge separation is mediated by symmetry-breaking vibrations of relatively low frequency, which implies that temperature should be accounted for to obtain reliable estimates of the charge transfer rate. Y1 - 2022 U6 - https://doi.org/10.1063/5.0089887 SN - 0021-9606 SN - 1089-7690 VL - 156 IS - 18 PB - AIP Publishing CY - Melville ER - TY - JOUR A1 - Tetenoire, Auguste A1 - Ehlert, Christopher A1 - Juaristi, Joseba Iñaki A1 - Saalfrank, Peter A1 - Alducin, Maite T1 - Why ultrafast photoinduced CO desorption dominates over oxidation on Ru(0001) JF - The journal of physical chemistry letters N2 - CO oxidation on Ru(0001) is a long-standing example of a reaction that, being thermally forbidden in ultrahigh vacuum, can be activated by femtosecond laser pulses. In spite of its relevance, the precise dynamics of the photoinduced oxidation process as well as the reasons behind the dominant role of the competing CO photodesorption remain unclear. Here we use ab initio molecular dynamics with electronic friction that account for the highly excited and nonequilibrated system created by the laser to investigate both reactions. Our simulations successfully reproduce the main experimental findings: the existence of photoinduced oxidation and desorption, the large desorption to oxidation branching ratio, and the changes in the O K-edge X-ray absorption spectra attributed to the initial stage of the oxidation process. Now, we are able to monitor in detail the ultrafast CO desorption and CO oxidation occurring in the highly excited system and to disentangle what causes the unexpected inertness to the otherwise energetically favored oxidation. Y1 - 2022 U6 - https://doi.org/10.1021/acs.jpclett.2c02327 SN - 1948-7185 VL - 13 IS - 36 SP - 8516 EP - 8521 PB - American Chemical Society CY - Washington, DC ER - TY - JOUR A1 - Choudhury, Arnab A1 - DeVine, Jessalyn A. A. A1 - Sinha, Shreya A1 - Lau, Jascha Alexander A1 - Kandratsenka, Alexander A1 - Schwarzer, Dirk A1 - Saalfrank, Peter A1 - Wodtke, Alec Michael T1 - Condensed-phase isomerization through tunnelling gateways JF - Nature : the international weekly journal of science N2 - Quantum mechanical tunnelling describes transmission of matter waves through a barrier with height larger than the energy of the wave(1). Tunnelling becomes important when the de Broglie wavelength of the particle exceeds the barrier thickness; because wavelength increases with decreasing mass, lighter particles tunnel more efficiently than heavier ones. However, there exist examples in condensed-phase chemistry where increasing mass leads to increased tunnelling rates(2). In contrast to the textbook approach, which considers transitions between continuum states, condensed-phase reactions involve transitions between bound states of reactants and products. Here this conceptual distinction is highlighted by experimental measurements of isotopologue-specific tunnelling rates for CO rotational isomerization at an NaCl surface(3,4), showing nonmonotonic mass dependence. A quantum rate theory of isomerization is developed wherein transitions between sub-barrier reactant and product states occur through interaction with the environment. Tunnelling is fastest for specific pairs of states (gateways), the quantum mechanical details of which lead to enhanced cross-barrier coupling; the energies of these gateways arise nonsystematically, giving an erratic mass dependence. Gateways also accelerate ground-state isomerization, acting as leaky holes through the reaction barrier. This simple model provides a way to account for tunnelling in condensed-phase chemistry, and indicates that heavy-atom tunnelling may be more important than typically assumed. Y1 - 2022 U6 - https://doi.org/10.1038/s41586-022-05451-0 SN - 0028-0836 SN - 1476-4687 VL - 612 IS - 7941 SP - 691 EP - 695 PB - Macmillan Publishers Limited, part of Springer Nature CY - London ER - TY - JOUR A1 - Kapernaum, Nadia A1 - Lange, Alyna A1 - Ebert, Max A1 - Grunwald, Marco A. A1 - Häge, Christian A1 - Marino, Sebastian A1 - Zens, Anna A1 - Taubert, Andreas A1 - Gießelmann, Frank A1 - Laschat, Sabine T1 - Current topics in ionic liquid crystals JF - ChemPlusChem N2 - Ionic liquid crystals (ILCs), that is, ionic liquids exhibiting mesomorphism, liquid crystalline phases, and anisotropic properties, have received intense attention in the past years. Among others, this is due to their special properties arising from the combination of properties stemming from ionic liquids and from liquid crystalline arrangements. Besides interesting fundamental aspects, ILCs have been claimed to have tremendous application potential that again arises from the combination of properties and architectures that are not accessible otherwise, or at least not accessible easily by other strategies. The current review highlights recent developments in ILC research, starting with some key fundamental aspects. Further subjects covered include the synthesis and variations of modern ILCs, including the specific tuning of their mesomorphic behavior. The review concludes with reflections on some applications that may be within reach for ILCs and finally highlights a few key challenges that must be overcome prior and during true commercialization of ILCs. KW - electrochemistry KW - ionic liquid crystals KW - mesogen mesophases KW - self-assembly KW - X-ray diffraction Y1 - 2021 U6 - https://doi.org/10.1002/cplu.202100397 SN - 2192-6506 VL - 87 IS - 1 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Hartlieb, Matthias T1 - Photo-iniferter RAFT polymerization JF - Macromolecular rapid communications : publishing the newsletters of the European Polymer Federation N2 - Light-mediated polymerization techniques offer distinct advantages over polymerization reactions fueled by thermal energy, such as high spatial and temporal control as well as the possibility to work under mild reaction conditions. Reversible addition-fragmentation chain-transfer (RAFT) polymerization is a highly versatile radical polymerization method that can be utilized to control a variety of monomers and produce a vast number of complex macromolecular structures. The use of light to drive a RAFT-polymerization is possible via multiple routes. Besides the use of photo-initiators, or photo-catalysts, the direct activation of the chain transfer agent controlling the RAFT process in a photo-iniferter (PI) process is an elegant way to initiate and control polymerization reactions. Within this review, PI-RAFT polymerization and its advantages over the conventional RAFT process are discussed in detail. KW - light KW - photo-iniferter reversible addition-fragmentation chain-transfer KW - photo-mediated polymerization KW - radical polymerization KW - reversible KW - addition-fragmentation chain-transfer polymerization Y1 - 2021 U6 - https://doi.org/10.1002/marc.202100514 SN - 1521-3927 VL - 43 IS - 1 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Liu, Yue A1 - Gould, Oliver E. C. A1 - Kratz, Karl A1 - Lendlein, Andreas T1 - On demand sequential release of (sub)micron particles controlled by size and temperature JF - Small : nano micro N2 - Polymeric devices capable of releasing submicron particles (subMP) on demand are highly desirable for controlled release systems, sensors, and smart surfaces. Here, a temperature-memory polymer sheet with a programmable smooth surface served as matrix to embed and release polystyrene subMP controlled by particle size and temperature. subMPs embedding at 80 degrees C can be released sequentially according to their size (diameter D of 200 nm, 500 nm, 1 mu m) when heated. The differences in their embedding extent are determined by the various subMPs sizes and result in their distinct release temperatures. Microparticles of the same size (D approximate to 1 mu m) incorporated in films at different programming temperatures T-p (50, 65, and 80 degrees C) lead to a sequential release based on the temperature-memory effect. The change of apparent height over the film surface is quantified using atomic force microscopy and the realization of sequential release is proven by confocal laser scanning microscopy. The demonstration and quantification of on demand subMP release are of technological impact for assembly, particle sorting, and release technologies in microtechnology, catalysis, and controlled release. KW - on demand particle release KW - temperature-memory effect KW - thermosensitive KW - polymer surface Y1 - 2022 U6 - https://doi.org/10.1002/smll.202104621 SN - 1613-6810 SN - 1613-6829 VL - 18 IS - 5 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Moradian, Hanieh A1 - Gossen, Manfred A1 - Lendlein, Andreas T1 - Co-delivery of genes can be confounded by bicistronic vector design JF - MRS Communications N2 - Maximizing the efficiency of nanocarrier-mediated co-delivery of genes for co-expression in the same cell is critical for many applications. Strategies to maximize co-delivery of nucleic acids (NA) focused largely on carrier systems, with little attention towards payload composition itself. Here, we investigated the effects of different payload designs: co-delivery of two individual "monocistronic" NAs versus a single bicistronic NA comprising two genes separated by a 2A self-cleavage site. Unexpectedly, co-delivery via the monocistronic design resulted in a higher percentage of co-expressing cells, while predictive co-expression via the bicistronic design remained elusive. Our results will aid the application-dependent selection of the optimal methodology for co-delivery of genes. KW - Molecular KW - Packaging KW - Protein Y1 - 2022 U6 - https://doi.org/10.1557/s43579-021-00128-7 SN - 2159-6859 SN - 2159-6867 VL - 12 IS - 2 SP - 145 EP - 153 PB - Springer CY - Heidelberg ER - TY - JOUR A1 - Lindic, Tilen A1 - Sinha, Shreya A1 - Mattsson, Stefan A1 - Paulus, Beate T1 - Prediction of a model crystal structure for Ni2F5 by first-principles calculations JF - Zeitschrift für Naturforschung : B, Chemical sciences N2 - Electrochemical fluorination in anhydrous HF, also known as the Simons process, is a widely used industrial method for fluorination of organic compounds. Its mechanism, being not so well understood, has long been debated and is believed to involve higher valent nickel fluorides formed on the nickel-plated anode during the process. One of these is speculated to be Ni2F5, which was previously reported in the literature and assigned via infrared spectroscopy, but its crystal structure is not yet known. We have identified known crystal structures of compounds with similar stoichiometries as Ni2F5 and utilized them as a starting point for our periodic DFT investigations, applying the PBE+U method. Ni2F5 as the most stable polymorph was found to be of the same crystal structure as another mixed valent fluoride, Cr2F5. The calculated lattice parameters are a = 7.24 angstrom, b = 7.40 angstrom, c = 7.08 angstrom and beta = 118.9 degrees with an antiferromagnetic ordering of the nickel magnetic moments. KW - crystal structure prediction KW - DFT KW - Ni2F5 Y1 - 2022 U6 - https://doi.org/10.1515/znb-2022-0072 SN - 0932-0776 SN - 1865-7117 VL - 77 IS - 6 SP - 469 EP - 473 PB - De Gruyter CY - Berlin ER - TY - JOUR A1 - Kossmann, Janina A1 - Sanchez-Manjavacas, Maria Luz Ortiz A1 - Brandt, Jessica A1 - Heil, Tobias A1 - López-Salas, Nieves A1 - Albero, Josep T1 - Mn(ii) sub-nanometric site stabilization in noble, N-doped carbonaceous materials for electrochemical CO2 reduction JF - Chemical communications : ChemComm / The Royal Society of Chemistry N2 - The preparation of stable and efficient electrocatalysts comprising abundant and non-critical row-materials is of paramount importance for their industrial implementation. Herein, we present a simple synthetic route to prepare Mn(ii) sub-nanometric active sites over a highly N-doped noble carbonaceous support. This support not only promotes a strong stabilization of the Mn(ii) sites, improving its stability against oxidation, but also provides a convenient coordination environment in the Mn(ii) sites able to produce CO, HCOOH and CH3COOH from electrochemical CO2 reduction. Y1 - 2022 U6 - https://doi.org/10.1039/d2cc00585a SN - 1359-7345 SN - 1364-548X VL - 58 IS - 31 SP - 4841 EP - 4844 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - López de Guereñu Kurganova, Anna A1 - Klier, Dennis Tobias A1 - Haubitz, Toni A1 - Kumke, Michael Uwe T1 - Influence of Gd3+ doping concentration on the properties of Na(Y,Gd)F-4 BT - Yb3+, Tm3+ upconverting nanoparticles and their long-term aging behavior JF - Photochemical & photobiological sciences / European Society for Photobiology N2 - We present a systematic study on the properties of Na(Y,Gd)F-4-based upconverting nanoparticles (UCNP) doped with 18% Yb3+, 2% Tm3+, and the influence of Gd3+ (10-50 mol% Gd3+). UCNP were synthesized via the solvothermal method and had a range of diameters within 13 and 50 nm. Structural and photophysical changes were monitored for the UCNP samples after a 24-month incubation period in dry phase and further redispersion. Structural characterization was performed by means of X-ray diffraction (XRD), transmission electron microscopy (TEM) as well as dynamic light scattering (DLS), and the upconversion luminescence (UCL) studies were executed at various temperatures (from 4 to 295 K) using time-resolved and steady-state spectroscopy. An increase in the hexagonal lattice phase with the increase of Gd3+ content was found, although the cubic phase was prevalent in most samples. The Tm3+-luminescence intensity as well as the Tm3+-luminescence decay times peaked at the Gd3+ concentration of 30 mol%. Although the general upconverting luminescence properties of the nanoparticles were preserved, the 24-month incubation period lead to irreversible agglomeration of the UCNP and changes in luminescence band ratios and lifetimes. KW - Upconversion luminescence KW - Lanthanides KW - Near infra-red KW - Ultra-low KW - temperature KW - Time-resolved spectroscopy Y1 - 2022 U6 - https://doi.org/10.1007/s43630-021-00161-4 SN - 1474-905X SN - 1474-9092 VL - 21 IS - 2 SP - 235 EP - 245 PB - Springer CY - Heidelberg ER - TY - JOUR A1 - Behrens, Karsten A1 - Balischewski, Christian A1 - Sperlich, Eric A1 - Menski, Antonia Isabell A1 - Balderas-Valadez, Ruth Fabiola A1 - Pacholski, Claudia A1 - Günter, Christina A1 - Lubahn, Susanne A1 - Kelling, Alexandra A1 - Taubert, Andreas T1 - Mixed chloridometallate(ii) ionic liquids with tunable color and optical response for potential ammonia sensors JF - RSC Advances N2 - Eight d-metal-containing N-butylpyridinium ionic liquids (ILs) with the nominal composition (C4Py)2[Ni0.5M0.5Cl4] or (C4Py)2[Zn0.5M0.5Cl4] (M = Cu, Co, Mn, Ni, Zn; C4Py = N-butylpyridinium) were synthesized, characterized, and investigated for their optical properties. Single crystal and powder X-ray analysis shows that the compounds are isostructural to existing examples based on other d-metal ions. Inductively coupled plasma optical emission spectroscopy measurements confirm that the metal/metal ratio is around 50 : 50. UV-Vis spectroscopy shows that the optical absorption can be tuned by selection of the constituent metals. Moreover, the compounds can act as an optical sensor for the detection of gases such as ammonia as demonstrated via a simple prototype setup. Y1 - 2022 U6 - https://doi.org/10.1039/d2ra05581c SN - 2046-2069 VL - 12 SP - 35072 EP - 35082 PB - RSC CY - London ER - TY - JOUR A1 - Pilar Yeste, Maria A1 - Carlos Hernandez-Garrido, Juan A1 - Kumke, Michael Uwe A1 - Alvarado, Sarah A1 - Cauqui, Miguel Angel A1 - Juan Calvino, Jose A1 - Primus, Philipp-Alexander T1 - Low-temperature growth of reactive pyrochlore nanostructures on Zirconia-supported ceria BT - implications for improved catalytic behavior JF - ACS applied nano materials N2 - The use of a catalyst support for the design of nanoscale heterogeneous catalysts based on cerium oxide offers vast possibilities for future catalyst development, particularly with regard to an increased focus on the use of renewable biogas and an emerging hydrogen economy. In this study, zirconia-supported ceria catalysts were synthesized, activated by using different thermochemical treatments, and characterized by way of temperature-programmed reduction (TPR), oxygen storage capacity, Xray diffraction, electron microscopy, and luminescence spectroscopy using Eu3+ as a spectroscopic probe. Through reduction-oxidation pretreatment routines, reactive pyrochlore structures were created at temperatures as low as 600 degrees C and identified through TPR and electron microscopy experiments. A structural relationship and alignment of the crystal planes is revealed in high-resolution scanning transmission electron microscopy experiments through the digital diffraction patterns. Low-temperature pretreatment induces the formation of reactive pyrochlore domains under retention of the surface area of the catalyst system, and no further morphological changes are detected. Furthermore, the formation of pyrochlore domains achieved through severe reduction and mild reoxidation (SRMO) treatments is reversible. Over multiple alternating SRMO and severe reduction and severe reoxidation (SRSO) treatments, europium spectroscopy and TPR results indicate that pyrochlore structures are recreated over consecutive treatments, whenever the mild oxidation step at 500 degrees C is the last treatment (SRMO, SRMO-SRSO-SRMO, etc.). KW - pyrochlore KW - nanocomposite KW - ceria KW - zirconia KW - supported catalyst KW - oxygen KW - storage capacity Y1 - 2022 U6 - https://doi.org/10.1021/acsanm.2c00416 SN - 2574-0970 VL - 5 IS - 5 SP - 6316 EP - 6326 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Mazurek-Budzyńska, Magdalena A1 - Behl, Marc A1 - Neumann, Richard A1 - Lendlein, Andreas T1 - 4D-actuators by 3D-printing combined with water-based curing JF - Materials today. Communications N2 - The shape and the actuation capability of state of the art robotic devices typically relies on multimaterial systems from a combination of geometry determining materials and actuation components. Here, we present multifunctional 4D-actuators processable by 3D-printing, in which the actuator functionality is integrated into the shaped body. The materials are based on crosslinked poly(carbonate-urea-urethane) networks (PCUU), synthesized in an integrated process, applying reactive extrusion and subsequent water-based curing. Actuation capability could be added to the PCUU, prepared from aliphatic oligocarbonate diol, isophorone diisocyanate (IPDI) and water, in a thermomechanical programming process. When programmed with a strain of epsilon(prog) = 1400% the PCUU networks exhibited actuation apparent by reversible elongation epsilon'(rev) of up to 22%. In a gripper a reversible bending epsilon'(rev)((be)(nd)()) in the range of 37-60% was achieved when the actuation temperature (T-high) was varied between 45 degrees C and 49 degrees C. The integration of actuation and shape formation could be impressively demonstrated in two PCUU-based reversible fastening systems, which were able to hold weights of up to 1.1 kg. In this way, the multifunctional materials are interesting candidate materials for robotic applications where a freedom in shape design and actuation is required as well as for sustainable fastening systems. KW - 4D-actuation KW - 3D-printing KW - Ink KW - Gripper KW - Fastener Y1 - 2022 U6 - https://doi.org/10.1016/j.mtcomm.2021.102966 SN - 2352-4928 VL - 30 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Mayer, Dennis A1 - Lever, Fabiano A1 - Picconi, David A1 - Metje, Jan A1 - Ališauskas, Skirmantas A1 - Calegari, Francesca A1 - Düsterer, Stefan A1 - Ehlert, Christopher A1 - Feifel, Raimund A1 - Niebuhr, Mario A1 - Manschwetus, Bastian A1 - Kuhlmann, Marion A1 - Mazza, Tommaso A1 - Robinson, Matthew Scott A1 - Squibb, Richard James A1 - Trabattoni, Andrea A1 - Wallner, Måns A1 - Saalfrank, Peter A1 - Wolf, Thomas J. A. A1 - Gühr, Markus T1 - Following excited-state chemical shifts in molecular ultrafast x-ray photoelectron spectroscopy JF - Nature Communications N2 - The conversion of photon energy into other energetic forms in molecules is accompanied by charge moving on ultrafast timescales. We directly observe the charge motion at a specific site in an electronically excited molecule using time-resolved x-ray photoelectron spectroscopy (TR-XPS). We extend the concept of static chemical shift from conventional XPS by the excited-state chemical shift (ESCS), which is connected to the charge in the framework of a potential model. This allows us to invert TR-XPS spectra to the dynamic charge at a specific atom. We demonstrate the power of TR-XPS by using sulphur 2p-core-electron-emission probing to study the UV-excited dynamics of 2-thiouracil. The method allows us to discover that a major part of the population relaxes to the molecular ground state within 220–250 fs. In addition, a 250-fs oscillation, visible in the kinetic energy of the TR-XPS, reveals a coherent exchange of population among electronic states. Y1 - 2022 U6 - https://doi.org/10.1038/s41467-021-27908-y SN - 2041-1723 VL - 13 PB - Springer Nature CY - Berlin ER - TY - JOUR A1 - Penschke, Christopher A1 - Edler von Zander, Robert A1 - Beqiraj, Alkit A1 - Zehle, Anna A1 - Jahn, Nicolas A1 - Neumann, Rainer A1 - Saalfrank, Peter T1 - Water on porous, nitrogen-containing layered carbon materials BT - the performance of computational model chemistries JF - Physical chemistry, chemical physics : PCCP ; a journal of European chemical societies / RSC, Royal Society of Chemistry N2 - Porous, layered materials containing sp(2)-hybridized carbon and nitrogen atoms, offer through their tunable properties, a versatile route towards tailormade catalysts for electrochemistry and photochemistry. A key molecule interacting with these quasi two-dimensional materials (2DM) is water, and a photo(electro)chemical key reaction catalyzed by them, is water splitting into H-2 and O-2, with the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) as half reactions. The complexity of some C/N-based 2DM in contact with water raises special needs for their theoretical modelling, which in turn is needed for rational design of C/N-based catalysts. In this work, three classes of C/N-containing porous 2DM with varying pore sizes and C/N ratios, namely graphitic carbon nitride (g-C3N4), C2N, and poly(heptazine imides) (PHI), are studied with various computational methods. We elucidate the performance of different models and model chemistries (the combination of electronic structure method and basis set) for water and water fragment adsorption in the low-coverage regime. Further, properties related to the photo(electro)chemical activity like electrochemical overpotentials, band gaps, and optical excitation energies are in our focus. Specifically, periodic models will be tested vs. cluster models, and density functional theory (DFT) vs. wavefunction theory (WFT). This work serves as a basis for a systematic study of trends for the photo(electro)chemical activity of C/N-containing layered materials as a function of water content, pore size and density. Y1 - 2022 U6 - https://doi.org/10.1039/d2cp00657j SN - 1463-9076 SN - 1463-9084 VL - 24 IS - 24 SP - 14709 EP - 14726 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Lood, Kajsa A1 - Tikk, Triin A1 - Krüger, Mandy A1 - Schmidt, Bernd T1 - Methylene capping facilitates cross-metathesis reactions of enals BT - a short synthesis of 7-methoxywutaifuranal from the xylochemical isoeugenol JF - The journal of organic chemistry N2 - Four combinations of type-I olefins isoeugenol and 4-hydroxy-3-methoxystyrene with type-II olefins acrolein and crotonaldehyde were investigated in cross-metathesis (CM) reactions. While both type-I olefins are suitable CM partners for this transformation, we observed synthetically useful conversions only with type-II olefin crotonaldehyde. For economic reasons, isoeugenol, a cheap xylochemical available from renewable lignocellulose or from clove oil, is the preferred type-I CM partner. Nearly quantitative conversions to coniferyl aldehyde by the CM reaction of isoeugenol and crotonaldehyde can be obtained at ambient temperature without a solvent or at high substrate concentrations of 2 mol.L-1 with the second-generation Hoveyda-Grubbs catalyst. Under these conditions, the ratio of reactants can be reduced to 1:1.5 and catalyst loadings as low as 0.25 mol % are possible. The high reactivity of the isoeugenol/crotonaldehyde combination in olefin metathesis reactions was demonstrated by a short synthesis of the natural product 7-methoxywutaifuranal, which was obtained from isoeugenol in a 44% yield over five steps. We suggest that the superior performance of crotonaldehyde in the CM reactions investigated can be rationalized by "methylene capping", i.e., the steric stabilization of the propagating Ru-alkylidene species. KW - Aldehydes KW - Catalysts KW - Hydrocarbons KW - Metathesis KW - Mixtures Y1 - 2022 U6 - https://doi.org/10.1021/acs.joc.1c02851 SN - 0022-3263 SN - 1520-6904 VL - 87 IS - 5 SP - 3079 EP - 3088 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Wessig, Pablo A1 - Badetko, Dominik A1 - Czarnecki, Maciej A1 - Wichterich, Lukas A1 - Schmidt, Peter A1 - Brudy, Cosima A1 - Sperlich, Eric A1 - Kelling, Alexandra T1 - Studies toward the total synthesis of arylnaphthalene lignans via a Photo-Dehydro-Diels-Alder (PDDA) reaction JF - The journal of organic chemistry N2 - An efficient method for the preparation of arylnaphthalene lignans (ANLs) was developed, which is based on thePhoto-Dehydro-DIELS-ALDER(PDDA) reaction. While intermolecular PDDA reactions turned out to be inefficient, theintramolecular variant using suberic acid as tether linking two aryl propiolic esters smoothly provided naphthalenophanes. Theirradiations were performed with a previously developed annular continuous-flow reactor and UVB lamps. In this way, the naturalproducts Alashinol D, Taiwanin C, and an unnamed ANL could be prepared. Y1 - 2022 U6 - https://doi.org/10.1021/acs.joc.2c00195 SN - 0022-3263 SN - 1520-6904 VL - 87 IS - 9 SP - 5904 EP - 5915 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Raju, Rajarshi Roy A1 - Koetz, Joachim T1 - Pickering Janus emulsions stabilized with gold nanoparticles JF - Langmuir : the ACS journal of surfaces and colloids / American Chemical Society N2 - We report a modified approach to the batch scale preparation of completely engulfed core-shell emulsions or partially engulfed Janus emulsions with colorful optical properties, containing water, olive oil, and silicone oil. The in situ reduction of gold chloride, forming gold nanoparticles (AuNPs) at the olive oil interface in the absence or presence of chitosan, leads to the formation of compartmentalized olive-silicone oil emulsion droplets in water. In the absence of additional reducing components, time-dependent morphological transformations from partial engulfment to complete engulfment were observed. Similar experiments in the presence of chitosan or presynthesized AuNPs show an opposite time-dependent trend of transformation of core-shell structures into partially engulfed ones. This behavior can be understood by a time-dependent rearrangement of the AuNPs at the interface and changes of the interfacial tension. The Pickering effect of AuNPs at oil-water and oil-oil interfaces brings not only color effects to individual microdroplets, which are of special relevance for the preparation of new optical elements, but also a surprising self-assembly of droplets. Y1 - 2022 U6 - https://doi.org/10.1021/acs.langmuir.1c02256 SN - 0743-7463 SN - 1520-5827 VL - 38 IS - 1 SP - 147 EP - 155 PB - American Chemical Society CY - Washington ER -