TY  - JOUR
A1  - Hagspiel, Stephan
A1  - Fantuzzi, Felipe
A1  - Dewhurst, Rian D.
A1  - Gärtner, Annalena
A1  - Lindl, Felix
A1  - Lamprecht, Anna
A1  - Braunschweig, Holger
T1  - Addukte des Stammboraphosphaketens H\(_{2}\)BPCO und deren Insertionsreaktionen mittels Decarbonylierung
JF  - Angewandte Chemie
N2  - Die ersten Beispiele für Lewis-Basen-Addukte des Stammboraphosphaketens H\(_{2}\)B-PCO und ihre cyclischen Dimere wurden hergestellt. Eines dieser Addukte zeigt unter milden Bedingungen eine Decarbonylierung und anschließende Insertion des Phosphinidens in die B-C-Bindung eines Borols, was in der Bildung sehr seltener Beispiele für 1,2-Phosphaborinine, B,P-Isostere von Benzol, resultiert. Die starken Donoreigenschaften dieser 1,2-Phosphaborinine wurden durch die Synthese ihrer π-Komplexe mit Metallen der Gruppe 6 bestätigt.
KW  - Bor
KW  - Decarbonylierung
KW  - Heterocyclen
KW  - Ketene
KW  - Phosphor
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-244803
VL  - 133
IS  - 24
SP  - 13780
EP  - 13784
ER  - 
TY  - JOUR
A1  - Gerlach, Marius
A1  - Monninger, Sophie
A1  - Schleier, Domenik
A1  - Hemberger, Patrick
A1  - Goettel, James T.
A1  - Braunschweig, Holger
A1  - Fischer, Ingo
T1  - Photoelectron Photoion Coincidence Spectroscopy of NCl\(_{3}\) and NCl\(_{2}\)
JF  - ChemPhysChem
N2  - We investigate NCl\(_{3}\) and the NCl\(_{2}\) radical by photoelectron-photoion coincidence spectroscopy using synchrotron radiation. The mass selected threshold photoelectron spectrum (ms-TPES) of NCl\(_{3}\) is broad and unstructured due to the large geometry change. An ionization energy of 9.7±0.1 eV is estimated from the spectrum and supported by computations. NCl2 is generated by photolysis at 213 nm from NCl\(_{3}\) and its ms-TPES shows an extended vibrational progression with a 90 meV spacing that is assigned to the symmetric N−Cl stretching mode in the cation. An adiabatic ionization energy of 9.94 ± 0.02 eV is determined.
KW  - radicals
KW  - photoelectron spectroscopy
KW  - synchrotron radiation
KW  - nitrogen trichloride
KW  - photolysis
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-257322
VL  - 22
IS  - 21
ER  - 
TY  - JOUR
A1  - Dostál, Jakub
A1  - Fennel, Franziska
A1  - Koch, Federico
A1  - Herbst, Stefanie
A1  - Würthner, Frank
A1  - Brixner, Tobias
T1  - Direct observation of exciton–exciton interactions
JF  - Nature Communications
N2  - Natural light harvesting as well as optoelectronic and photovoltaic devices depend on efficient transport of energy following photoexcitation. Using common spectroscopic methods, however, it is challenging to discriminate one-exciton dynamics from multi-exciton interactions that arise when more than one excitation is present in the system. Here we introduce a coherent two-dimensional spectroscopic method that provides a signal only in case that the presence of one exciton influences the behavior of another one. Exemplarily, we monitor exciton diffusion by annihilation in a perylene bisimide-based J-aggregate. We determine quantitatively the exciton diffusion constant from exciton–exciton-interaction 2D spectra and reconstruct the annihilation-free dynamics for large pump powers. The latter enables for ultrafast spectroscopy at much higher intensities than conventionally possible and thus improves signal-to-noise ratios for multichromophore systems; the former recovers spatio–temporal dynamics for a broad range of phenomena in which exciton interactions are present.
KW  - energy transfer
KW  - self-assembly
KW  - optical spectroscopy
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-226271
VL  - 9
ER  - 
TY  - JOUR
A1  - Dietschreit, Johannes C. B.
A1  - Wagner, Annika
A1  - Le, T. Anh
A1  - Klein, Philipp
A1  - Schindelin, Hermann
A1  - Opatz, Till
A1  - Engels, Bernd
A1  - Hellmich, Ute A.
A1  - Ochsenfeld, Christian
T1  - Predicting \(^{19}\)F NMR Chemical Shifts: A Combined Computational and Experimental Study of a Trypanosomal Oxidoreductase–Inhibitor Complex
JF  - Angewandte Chemie International Edition
N2  - The absence of fluorine from most biomolecules renders it an excellent probe for NMR spectroscopy to monitor inhibitor–protein interactions. However, predicting the binding mode of a fluorinated ligand from a chemical shift (or vice versa) has been challenging due to the high electron density of the fluorine atom. Nonetheless, reliable \(^{19}\)F chemical‐shift predictions to deduce ligand‐binding modes hold great potential for in silico drug design. Herein, we present a systematic QM/MM study to predict the \(^{19}\)F NMR chemical shifts of a covalently bound fluorinated inhibitor to the essential oxidoreductase tryparedoxin (Tpx) from African trypanosomes, the causative agent of African sleeping sickness. We include many protein–inhibitor conformations as well as monomeric and dimeric inhibitor–protein complexes, thus rendering it the largest computational study on chemical shifts of \(^{19}\)F nuclei in a biological context to date. Our predicted shifts agree well with those obtained experimentally and pave the way for future work in this area.
KW  - African sleeping sickness
KW  - covalent inhibitors
KW  - NMR spectroscopy
KW  - quantum chemistry
KW  - structural biology
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-214879
VL  - 59
IS  - 31
SP  - 12669
EP  - 12673
ER  - 
TY  - JOUR
A1  - Brunecker, Carina
A1  - Müssig, Jonas H.
A1  - Arrowsmith, Merle
A1  - Fantuzzi, Felipe
A1  - Stoy, Andreas
A1  - Böhnke, Julian
A1  - Hofmann, Alexander
A1  - Bertermann, Rüdiger
A1  - Engels, Bernd
A1  - Braunschweig, Holger
T1  - Boranediyl‐ and Diborane(4)‐1,2‐diyl‐Bridged Platinum A‐Frame Complexes
JF  - Chemistry – A European Journal
N2  - Diplatinum A‐frame complexes with a bridging (di)boron unit in the apex position were synthesized in a single step by the double oxidative addition of dihalo(di)borane precursors at a bis(diphosphine)‐bridged Pt\(^{0}\)\(_{2}\) complex. While structurally analogous to well‐known μ‐borylene complexes, in which delocalized dative three‐center‐two‐electron M‐B‐M bonding prevails, theoretical investigations into the nature of Pt−B bonding in these A‐frame complexes show them to be rare dimetalla(di)boranes displaying two electron‐sharing Pt−B σ‐bonds. This is experimentally reflected in the low kinetic stability of these compounds, which are prone to loss of the (di)boron bridgehead unit.
KW  - boron
KW  - bonding
KW  - EDA-NOCV
KW  - oxidative addition
KW  - platinum
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-214707
VL  - 26
IS  - 39
SP  - 8518
EP  - 8523
ER  - 
TY  - JOUR
A1  - Ahmed, Bilal
A1  - Ojha, Animesh K.
A1  - Hirsch, Florian
A1  - Fischer, Ingo
A1  - Patrice, Donfack
A1  - Materny, Arnulf
T1  - Tailoring of enhanced interfacial polarization in WO\(_3\) nanorods grown over reduced graphene oxide synthesized by a one-step hydrothermal method
JF  - RSC Advances
N2  - In the present report, well-defined WO3 nanorods (NRs) and a rGO–WO\(_3\) composite were successfully synthesized using a one-pot hydrothermal method. The crystal phase, structural morphology, shape, and size of the as-synthesized samples were studied using X-ray diffraction (XRD) and transmission electron microscopy (TEM) measurements. The optical properties of the synthesized samples were investigated by Raman, ultraviolet-visible (UV-Vis) and photoluminescence (PL) spectroscopy. Raman spectroscopy and TEM results validate the formation of WO\(_3\) (NRs) on the rGO sheet. The value of the dielectric constant (ε′) of WO3 NRs and rGO–WO\(_3\) composite is decreased with an increase in frequency. At low frequency (2.5 to 3.5 Hz), the value of ε′ for the rGO–WO3 composite is greater than that of pure WO\(_3\) NRs. This could be due to the fact that the induced charges follow the ac signal. However, at higher frequency (3.4 to 6.0), the value of ε′ for the rGO–WO\(_3\) composite is less compared to that of the pure WO3 NRs. The overall decrease in the value of ε′ could be due to the occurrence of a polarization process at the interface of the rGO sheet and WO3 NRs. Enhanced interfacial polarization in the rGO–WO\(_3\) composite is observed, which may be attributed to the presence of polar functional groups on the rGO sheet. These functional groups trap charge carriers at the interface, resulting in an enhancement of the interfacial polarization. The value of the dielectric modulus is also calculated to further confirm this enhancement. The values of the ac conductivity of the WO\(_3\) NRs and rGO–WO\(_3\) composite were calculated as a function of the frequency. The greater value of the ac conductivity in the rGO–WO\(_3\) composite compared to that of the WO\(_3\) NRs confirms the restoration of the sp:\(^{++}\) network during the in situ synthesis of the rGO–WO\(_3\) composite, which is well supported by the results obtained by Raman spectroscopy.
KW  - chemistry
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-181829
VL  - 7
IS  - 23
ER  - 
TY  - JOUR
A1  - Aeschlimann, Martin
A1  - Brixner, Tobias
A1  - Cinchetti, Mirko
A1  - Frisch, Benjamin
A1  - Hecht, Bert
A1  - Hensen, Matthias
A1  - Huber, Bernhard
A1  - Kramer, Christian
A1  - Krauss, Enno
A1  - Loeber, Thomas H.
A1  - Pfeiffer, Walter
A1  - Piecuch, Martin
A1  - Thielen, Philip
T1  - Cavity-assisted ultrafast long-range periodic energy transfer between plasmonic nanoantennas
JF  - Light: Science & Applications
N2  - Radiationless energy transfer is at the core of diverse phenomena, such as light harvesting in photosynthesis\(^1\), energy-transfer-based microspectroscopies\(^2\), nanoscale quantum entanglement\(^3\) and photonic-mode hybridization\(^4\). Typically, the transfer is efficient only for separations that are much shorter than the diffraction limit. This hampers its application in optical communication and quantum information processing, which require spatially selective addressing. Here, we demonstrate highly efficient radiationless coherent energy transfer over a distance of twice the excitation wavelength by combining localized and delocalized\(^5\) plasmonic modes. Analogous to the Tavis-Cummings model, two whispering-gallery-mode antennas\(^6\) placed in the foci of an elliptical plasmonic cavity\(^7\) fabricated from single-crystal gold plates act as a pair of oscillators coupled to a common cavity mode. Time-resolved two-photon photoemission electron microscopy (TR 2P-PEEM) reveals an ultrafast long-range periodic energy transfer in accordance with the simulations. Our observations open perspectives for the optimization and tailoring of mesoscopic energy transfer and long-range quantum emitter coupling.
KW  - chemistry
KW  - nanocavities
KW  - nanophotonics and plasmonics
KW  - photonic devices
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-173265
VL  - 6
ER  - 
TY  - JOUR
A1  - Aeschlimann, Martin
A1  - Bauer, Michael
A1  - Bayer, Daniela
A1  - Brixner, Tobias
A1  - Cunovic, Stefan
A1  - Fischer, Alexander
A1  - Melchior, Pascal
A1  - Pfeiffer, Walter
A1  - Rohmer, Martin
A1  - Schneider, Christian
A1  - Strüber, Christian
A1  - Tuchscherer, Philip
A1  - Voronine, Dimitri V.
T1  - Optimal open-loop near-field control of plasmonic nanostructures
N2  - Optimal open-loop control, i.e. the application of an analytically derived control rule, is demonstrated for nanooptical excitations using polarization-shaped laser pulses. Optimal spatial near-field localization in gold nanoprisms and excitation switching is realized by applying a shift to the relative phase of the two polarization components. The achieved near-field switching confirms theoretical predictions, proves the applicability of predefined control rules in nanooptical light–matter interaction and reveals local mode interference to be an important control mechanism.
KW  - Chemie
Y1  - 2012
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-75256
ER  -