TY - JOUR A1 - He, Jiang A1 - Rauch, Florian A1 - Friedrich, Alexandra A1 - Sieh, Daniel A1 - Ribbeck, Tatjana A1 - Krummenacher, Ivo A1 - Braunschweig, Holger A1 - Finze, Maik A1 - Marder, Todd B. T1 - N-Heterocyclic Olefins as Electron Donors in Combination with Triarylborane Acceptors: Synthesis, Optical and Electronic Properties of D-π-A Compounds JF - Chemistry - A European Journal N2 - N‐heterocyclic olefins (NHOs), relatives of N‐heterocyclic carbenes (NHCs), exhibit high nucleophilicity and soft Lewis basic character. To investigate their π‐electron donating ability, NHOs were attached to triarylborane π‐acceptors (A) giving donor (D)–π–A compounds 1–3. In addition, an enamine π‐donor analogue (4) was synthesized for comparison. UV–visible absorption studies show a larger red shift for the NHO‐containing boranes than for the enamine analogue, a relative of cyclic (alkyl)(amino) carbenes (CAACs). Solvent‐dependent emission studies indicate that 1–4 have moderate intramolecular charge‐transfer (ICT) behavior. Electrochemical investigations reveal that the NHO‐containing boranes have extremely low reversible oxidation potentials (e.g., for 3, \(E^{ox}_{1/2}\) =−0.40 V vs. ferrocene/ferrocenium, Fc/Fc\(^+\), in THF). Time‐dependent (TD) DFT calculations show that the HOMOs of 1–3 are much more destabilized than that of the enamine‐containing 4, which confirms the stronger donating ability of NHOs. KW - donor-acceptor systems KW - electrochemistry KW - photophysical prosperties KW - N-heterocyclic olefins KW - triarylboranes Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-204690 VL - 25 ER - TY - JOUR A1 - Griesbeck, Stefanie A1 - Michail, Evripidis A1 - Rauch, Florian A1 - Ogasawara, Hiroaki A1 - Wang, Chenguang A1 - Sato, Yoshikatsu A1 - Edkins, Robert M. A1 - Zhang, Zuolun A1 - Taki, Masayasu A1 - Lambert, Christoph A1 - Yamaguchi, Shigehiro A1 - Marder, Todd B. T1 - The Effect of Branching on the One‐ and Two‐Photon Absorption, Cell Viability, and Localization of Cationic Triarylborane Chromophores with Dipolar versus Octupolar Charge Distributions for Cellular Imaging JF - Chemistry – A European Journal N2 - Two different chromophores, namely a dipolar and an octupolar system, were prepared and their linear and nonlinear optical properties as well as their bioimaging capabilities were compared. Both contain triphenylamine as the donor and a triarylborane as the acceptor, the latter modified with cationic trimethylammonio groups to provide solubility in aqueous media. The octupolar system exhibits a much higher two‐photon brightness, and also better cell viability and enhanced selectivity for lysosomes compared with the dipolar chromophore. Furthermore, both dyes were applied in two‐photon excited fluorescence (TPEF) live‐cell imaging. KW - boranes KW - cell imaging KW - fluorescence KW - lysosome KW - two-photon excited fluorescence Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-212887 VL - 25 IS - 57 SP - 13164 EP - 13175 ER - TY - JOUR A1 - Griesbeck, Stefanie A1 - Michail, Evripidis A1 - Rauch, Florian A1 - Ogasawara, Hiroaki A1 - Wang, Chenguang A1 - Sato, Yoshikatsu A1 - Edkins, Robert M. A1 - Zhang, Zuolun A1 - Taki, Masayasu A1 - Lambert, Christoph A1 - Yamaguchi, Shigehiro A1 - Marder, Todd B. T1 - The Effect of Branching on One- and Two-Photon Absorption, Cell Viability and Localization of Cationic Triarylborane Chromophores with Dipolar versus Octupolar Charge Distributions for Cellular Imaging JF - Chemistry - A European Journal N2 - Two different chromophores, namely a dipolar and an octupolar system, were prepared and their linear and nonlinear optical properties as well as their bioimaging capabilities were compared. Both contain triphenylamine as the donor and a triarylborane as the acceptor, the latter modified with cationic trimethylammonio groups to provide solubility in aqueous media. The octupolar system exhibits a much higher two‐photon brightness, and also better cell viability and enhanced selectivity for lysosomes compared with the dipolar chromophore. Furthermore, both dyes were applied in two‐photon excited fluorescence (TPEF) live‐cell imaging. KW - boranes KW - cell imaging KW - fluerescence KW - lysosome KW - two-photon excited fluorescence Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-204829 VL - 25 IS - 57 ER - TY - JOUR A1 - Belaidi, Houmam A1 - Rauch, Florian A1 - Zhang, Zuolun A1 - Latouche, Camille A1 - Boucekkine, Abdou A1 - Marder, Todd B. A1 - Halet, Jean-Francois T1 - Insights into the optical properties of triarylboranes with strongly electron-accepting bis(fluoromesityl)boryl groups: when theory meets experiment JF - ChemPhotoChem N2 - The photophysical properties (absorption, fluorescence and phosphorescence) of a series of triarylboranes of the form 4-D-C\(_6\)H\(_4\)-B(Ar)\(_2\) (D=\(^t\)Bu or NPh\(_2\); Ar=mesityl (Mes) or 2,4,6-tris(trifluoromethylphenyl (Fmes)) were analyzed theoretically using state-of-the-art DFT and TD-DFT methods. Simulated emission spectra and computed decay rate constants are in very good agreement with the experimental data. Unrestricted electronic computations including vibronic contributions explain the unusual optical behavior of 4-\(^t\)Bu-C\(_6\)H\(_4\)-B(Fmes)\(_2\) 2, which shows both fluorescence and phosphorescence at nearly identical energies (at 77 K in a frozen glass). Analysis of the main normal modes responsible for the phosphorescence vibrational fine structure indicates that the bulky tert-butyl group tethered to the phenyl ring is strongly involved. Interestingly, in THF solvent, the computed energies of the singlet and triplet excited states are very similar for compound 2 only, which may explain why 2 shows phosphorescence in contrast to the other members of the series. KW - boron KW - density functional calculations KW - luminescence KW - phosphorescence KW - photophysics KW - activated delayes flourescence KW - 3-coordinate organoboron compounds KW - light-emitting-diodes KW - phosphorescene spectra KW - molecular structures KW - high efficiency KW - pi-conjugation KW - trivalent boron KW - single photon KW - donor Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-205600 VL - 4 IS - 3 ER - TY - JOUR A1 - Lenczyk, Carsten A1 - Roy, Dipak Kumar A1 - Nitsch, Jörn A1 - Radacki, Krzysztof A1 - Rauch, Florian A1 - Dewhurst, Rian D. A1 - Bickelhaupt, F. Matthias A1 - Marder, Todd B. A1 - Braunschweig, Holger T1 - Steric Effects Dictate the Formation of Terminal Arylborylene Complexes of Ruthenium from Dihydroboranes JF - Chemistry - A European Journal N2 - The steric and electronic properties of aryl substituents in monoaryl borohydrides (Li[ArBH\(_3\)]) and dihydroboranes were systematically varied and their reactions with [Ru(PCy\(_3\))\(_2\)HCl(H\(_2\))] (Cy: cyclohexyl) were studied, resulting in bis(σ)‐borane or terminal borylene complexes of ruthenium. These variations allowed for the investigation of the factors involved in the activation of dihydroboranes in the synthesis of terminal borylene complexes. The complexes were studied by multinuclear NMR spectroscopy, mass spectrometry, X‐ray diffraction analysis, and density functional theory (DFT) calculations. The experimental and computational results suggest that the ortho‐substitution of the aryl groups is necessary for the formation of terminal borylene complexes. KW - Arylborylene Complexes KW - Ruthenium KW - Dihydroboranes KW - boranes KW - borohydrides KW - borylenes KW - steric effects KW - sigma boranes Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-219537 SN - 1521-3765 VL - 25 IS - 59 ER -