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101.
Grant J. Sherborne Avetik G. Gevondian Ignacio Funes‐Ardoiz Amit Dahiya Christoph Fricke Franziska Schoenebeck 《Angewandte Chemie (International ed. in English)》2020,59(36):15543-15548
Selective C –C couplings are powerful strategies for the rapid and programmable construction of bi‐ or multiaryls. To this end, the next frontier of synthetic modularity will likely arise from harnessing the coupling space that is orthogonal to the powerful Pd‐catalyzed coupling regime. This report details the realization of this concept and presents the fully selective arylation of aryl germanes (which are inert under Pd0/PdII catalysis) in the presence of the valuable functionalities C?BPin, C?SiMe3, C?I, C?Br, C?Cl, which in turn offer versatile opportunities for diversification. The protocol makes use of visible light activation combined with gold catalysis, which facilitates the selective coupling of C?Ge with aryl diazonium salts. Contrary to previous light‐/gold‐catalyzed couplings of Ar–N2+, which were specialized in Ar–N2+ scope, we present conditions to efficiently couple electron‐rich, electron‐poor, heterocyclic and sterically hindered aryl diazonium salts. Our computational data suggest that while electron‐poor Ar–N2+ salts are readily activated by gold under blue‐light irradiation, there is a competing dissociative deactivation pathway for excited electron‐rich Ar–N2+, which requires an alternative photo‐redox approach to enable productive couplings. 相似文献
102.
Albrecht Lindinger Stefan M. Weber Andrea Merli Franziska Sauer Mateusz Plewicki Ludger Wste 《Journal of photochemistry and photobiology. A, Chemistry》2006,180(3):256-261
We present two novel optimization methods by employing shaped fs-laser pulses in a closed feedback loop. The first describes control pulse cleaning where extraneous features were removed by applying genetic pressure on certain pulse components. The second reports parametric optimization with intuitive parameters such as subpulse distances, chirps, phase differences, and spectral peak patterns. These methods were conducted on the ionization process of alkali dimers produced in a molecular beam and improved the performances of the optimized pulses compared with short pulses at the same pulse energy. Moreover, we attempt to analyze the obtained pulse shapes regarding the underlying optimized processes. Further investigations concerning isotope selective fragmentation and optimal control of excitation processes of ultracold rubidium dimers in a magneto-optical trap (MOT) are also shown. 相似文献
103.
A Modular Class of Fluorescent Difluoroboranes: Synthesis,Structure, Optical Properties,Theoretical Calculations and Applications for Biological Imaging
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Sylvestre P. J. T. Bachollet Dr. Daniel Volz Béla Fiser Stephan Münch Dr. Franziska Rönicke Dr. Jokin Carrillo Harry Adams Prof. Ute Schepers Enrique Gómez‐Bengoa Prof. Stefan Bräse Prof. Joseph P. A. Harrity 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(35):12430-12438
Ten borylated bipyridines (BOBIPYs) have been synthesized and selected structural modifications have been made that allow useful structure–optical property relationships to be gathered. These systems have been further investigated using DFT calculations and spectroscopic measurements, showing blue to green fluorescence with quantum yields up to 41 %. They allow full mapping of the structure to determine where selected functionalities can be implemented, to tune the optical properties or to incorporate linking groups. The best derivative was thus functionalised with an alkyne linker, which would enable further applications through click chemistry and in this optic, the stability of the fluorophores has been evaluated. 相似文献
104.
A Boron‐Fluorinated Tris(pyrazolyl)borate Ligand (FTp*) and Its Mono‐ and Dinuclear Copper Complexes [Cu(FTp*)2] and [Cu2(FTp*)2]: Synthesis,Structures, and DFT Calculations
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Dr. Timo Augenstein Franziska Dorner Kevin Reiter Hanna E. Wagner Dr. Delphine Garnier Prof. Dr. Wim Klopper Prof. Dr. Frank Breher 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(23):7935-7943
Reaction of [Si(3,5‐Me2pz)4] ( 1 ) with [Cu(MeCN)4][BF4] ( 2 ) gave the mono‐ and dinuclear copper complexes [Cu2(FTp*)2] ( 3 ) and [Cu(FTp*)2] ( 4 ). Both complexes contain the so‐far unprecedented boron‐fluorinated FTp* ligand ([FB(3,5‐Me2pz)3]? with pz=pyrazolyl) originating from 1 , acting as a pyrazolyl transfer reagent, and the [BF4]? counter anion of 2 , serving as the source of the {BF} entity. The solid‐state structures as well as the NMR and EPR spectroscopic characteristics of the complexes were elaborated. Pulsed gradient spin echo (PGSE) experiments revealed that 3 retains (almost entirely) its dimeric structure in benzene, whereas dimer cleavage and formation of acetonitrile adducts, presumably [Cu(FTp*)(MeCN)], is observed in acetonitrile. The short Cu???Cu distance of 269.16 pm in the solid‐state is predicted by DFT calculations to be dictated by dispersion interactions between all atoms in the complex (the Cu?Cu dispersion contribution itself is only very small). As revealed by cyclic voltammetry studies, 3 shows an irreversible (almost quasi‐reversible at higher scan rates) oxidation process centred at Epa=?0.23 V (E01/2=?0.27 V) (vs. Fc/Fc+). Oxidation reactions on a preparative scale with one equivalent of the ferrocenium salt [Fc][BF4] (very slow reaction) or air (fast reaction) furnished blue crystals of the mononuclear copper(II) complex [Cu(FTp*)2] ( 4 ). As expected for a Jahn–Teller‐active system, the coordination sphere around copper(II) is strongly distorted towards a stretched octahedron, in accordance with EPR spectroscopic findings. 相似文献
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108.
Dr. Priyabrata Ghana Dr. Franziska D. van Krüchten Dr. Thomas P. Spaniol Prof. Dr. Jun Okuda 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(45):10718-10723
Protonolysis of the titanium alkyl complex [Ti(CH2SiMe3)(Xy-N3N)] (Xy-N3N=[{(3,5-Me2C6H3)NCH2CH2}3N]3−) supported by a triamidoamine ligand, with [NEt3H][B(3,5-Cl2C6H3)4] or [PhNMe2H][B(C6F5)4] afforded the cations [Ti(Xy-N3N)][A] (A−=[B(3,5-Cl2C6H3)4]− ( 1[B(ArCl)4] ; B(ArCl)4=tetrakis(3,5-dichlorophenyl)borate); A−=[B(C6F5)4]− ( 1[B(ArF)4] ; B(ArF)4=tetrakis[3,5-bis(trifluoromethyl)phenyl]borate). These Lewis acidic cations were reacted with coordinating solvents to afford the cations [Ti(L)(Xy-N3N)][B(C6F5)4] ( 2-L ; L=Et2O, pyridine and THF). XRD analysis revealed a trigonal monopyramidal (TMP) geometry for the tetracoordinate cations in 1[B(ArX)4] and trigonal bipyramidal (TBP) geometry for the pentacoordinate cations in 2-L . Variable-temperature NMR spectroscopy showed a dynamic equilibrium for 2-Et2O in solution, involving the dissociation of Et2O. Coordination to the titanium(IV) center activated the THF molecule, which, in the presence of NEt3, underwent ring-opening to give the titanium alkoxide [Ti(O(CH2)4NEt3)(Xy-N3N)][B(3,5-Cl2C6H3)4] ( 3 ). Hydride abstraction from Cβ,eq of the triamidoamine ligand arm in [Ti(CH2SiMe3)(Xy-N3N)] or [Ti(NMe2)(Xy-N3N)] with [Ph3C][B(3,5-Cl2C6H3)4] led to the diamidoamine–imine complex [Ti(R){(Xy-N=CHCH2)(Xy-NCH2CH2)2N}][B(3,5-Cl2C6H3)4] (R=CH2SiMe3 ( 4 a ); R=NMe2 ( 4 b )). Hydride addition to 4 b with [Li(THF)][HBPh3] gave [Ti(NMe2)(Xy-N3N)], whereas KH deprotonated further to give [Ti(NMe2){(Xy-NCH=CH)(Xy-NCH2CH2)2N}] ( 5 ). XRD on single crystals of 3 and 4 b confirmed the proposed structures. 相似文献
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