Christoph Wallach  Dr. Felix S. Geitner  Dr. Wilhelm Klein  Prof. Dr. Thomas F. Fässler 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(53):12349-12356

The synthetic approach towards molecules that contain Ge atoms with oxidation state 0, and which are exclusively connected to other Ge atoms, is explored by using anionic clusters extracted from binary solids. Besides providing a novel variable method for the introduction of alkenyl moieties to [Ge₉] cluster compounds, this work expands the spectrum of mixed-functionalized [Ge₉] cluster anions, which are suitable for the straightforward synthesis of zwitterionic compounds upon coordination to metal cations. In detail, the synthesis of a series of mixed-functionalized [Ge₉] clusters is reported, including [Ge₉{Si(TMS)₃}₃PRR^I] (R=tBu, R^I=(CH₂)₃CH=CH₂; 2 ) and [Ge₉{Si(TMS)₃}₂PRR^I]⁻ (R and R^I: alkyl, alkenyl, aryl, aminoalkyl; 3 a to 11 a , TMS: (trimethyl)silyl). In 2 and 3 a , pentenyl functionalization of the [Ge₉] clusters was achieved by reaction of the novel chlorophosphine tBu{(CH₂)₃CH=CH₂}PCl ( 1 ) with silylated [Ge₉] clusters. Furthermore, the reactivity of the cluster anions 3 a to 11 a towards NHC^DippMCl (NHC^Dipp=1,3-di(2,6-diisopropylphenyl)imidazolylidine; M=Cu, Ag) showed a dependency on the steric demand of the phosphine either zwitterions ( 3 -MNHC^Dipp to 7 -MNHC^Dipp) featuring P–M interactions are formed, or Ge–M coordination ( 8 -MNHC^Dipp to 11 -MNHC^Dipp) occurs. For M=Ag, the formation of zwitterionic complexes was unequivocally proven by NMR investigations showing ¹J(³¹P-¹⁰⁷Ag/¹⁰⁹Ag) spin-spin coupling.  相似文献   

    

Tim Kohlmann  Dr. Christoph Kerzig  Prof. Dr. Martin Goez 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(42):9991-9996

Upon irradiation with ns laser pulses at 355 nm, 2-aminoanthracene in SDS micelles readily produces hydrated electrons. These “super-reductants” rapidly attack substrates such as chloro-organics and convert them into carbon-centred radicals through dissociative electron transfer. For a catalytic cycle, the aminoanthracene needs to be restored from its photoionization by-product, the radical cation, by a sacrificial donor. The ascorbate monoanion can only achieve this across the micelle–water interface, but the monoanion of ascorbyl palmitate results in a fully micelle-contained regenerative electron source. The shielding by the micelle in the latter case not only increases the life of the catalyst but also strongly suppresses the interception of the carbon-centred radicals by the hydrogen-donating ascorbate moiety; and in conjunction with the high local concentrations effected by the pulsed laser, termination by radical dimerization thus dominates. We have obtained a complete and consistent picture through monitoring the individual steps and the assembled system by flash photolysis on fast and slow timescales, from microseconds to minutes; and in preparative studies on a variety of substrates, we have achieved up to quantitative dimerization with a turnover on the order of 1 mmol per hour.  相似文献   

    

Jakob Steube  Dipl.-Chem. Lukas Burkhardt  Ayla Päpcke  Johannes Moll  Dr. Peter Zimmer  Dr. Roland Schoch  Dr. Christoph Wölper  Prof. Dr. Katja Heinze  Prof. Dr. Stefan Lochbrunner  Prof. Dr. Matthias Bauer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(51):11826-11830

The complex class [Fe(N^N^C)(N^N^N)]⁺ with an Earth-abundant metal ion has been repeatedly suggested as a chromophore and potential photosensitizer on the basis of quantum chemical calculations. Synthesis and photophysical properties of the parent complex [Fe(pbpy)(tpy)]⁺ (Hpbpy=6-phenyl-2,2′-bipyridine and tpy=2,2′:6′,2′′-terpyridine) of this new chromophore class are now reported. Ground-state characterization by X-ray diffraction, electrochemistry, spectroelectrochemistry, UV/Vis, and X-ray spectroscopy in combination with DFT calculations proves the high impact of the cyclometalating ligand on the electronic structure. The photophysical properties are significantly improved compared to the prototypical [Fe(tpy)₂]²⁺ complex. In particular, the metal-to-ligand absorption extends into the near-IR and the ³MLCT lifetime increases by 5.5, whereas the metal-centered excited triplet state is very short-lived.  相似文献   

    

Christoph Schoo  Sebastian Bestgen  Alexander Egeberg  Jasmin Seibert  Sergey N. Konchenko  Claus Feldmann  Peter W. Roesky 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(13):4430-4434

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Christoph Freysoldt  Patrick Merz  Marcus Schmidt  Shrikant Mohitkar  Claudia Felser  Jrg Neugebauer  Martin Jansen 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(1):1-1

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Christoph Alberti  Dr. Felix Scheliga  Dr. Stephan Enthaler 《ChemistryOpen》2019,8(7):822-827

The chemical recycling of end-of-life plastic waste streams can contribute to a resource-conserving and sustainable society. This matter of recycling is composed of a sequence of depolymerization and subsequent polymerization reactions. In this regard, we have studied the chemical recycling of end-of-life poly(bisphenol A carbonate) applying phenol as depolymerization reagent. In the presence of catalytic amounts of alkali metal halides as products bisphenol A and diphenyl carbonate were obtained in excellent turnover frequencies of up to 1392 h⁻¹ and short reaction times. These depolymerization products offer the straightforward possibility to close the cycle by producing new poly(bisphenol A carbonate) and as second product phenol, which can be reused for further depolymerizations.  相似文献   

    

Tim-Oliver Kindler  Christoph Alberti  Jannis Sundermeier  Dr. Stephan Enthaler 《ChemistryOpen》2019,8(12):1410-1412

The valorization of waste to valuable chemicals can contribute to a more resource-efficient and circular chemistry. In this regard, the selective degradation of end-of-life polymers/plastics to produce useful chemical building blocks can be a promising target. We have investigated the hydrogenative depolymerization of end-of-life poly(bisphenol A carbonate). Applying catalytic amounts of the commercial available Ruthenium-MACHO-BH complex the end-of-life polycarbonate was converted to bisphenol A and methanol. Importantly, bisphenol A can be reprocessed for the manufacture of new poly-(bisphenol A carbonate) and methanol can be utilized as energy storage material.  相似文献   

    

Tom Kunde  Worarin Meesorn  Christoph Weder  Hans G. Brner 《Macromolecular rapid communications》2019,40(1)

A general strategy to modify the structurally interesting poly(lactonic sophorolipid) (Poly(LSL)), a polymer derived from the biobased sophorolipid monomer, is presented. Effective backbone modification is achieved via a triazolinedione (TAD)‐ene‐reaction. This enables the straightforward introduction of various functionalities to the double bond in the fatty acid segment of the Poly(LSL). The reaction occurs quantitatively in stoichiometric ratios up to a targeted functionalization degree of 50% and complete functionalization of all double bonds is feasible when three equivalents excess of the TAD moiety with respect to the double bonds are used. It is shown that the thermal and mechanical properties of the modified polymers can be tailored via type and degree of functionalization. The exploited TAD ligation fulfills the criteria of an economic and efficient reaction, making the presented modification strategy straightforward to fine‐tune the material properties and extending the applicability of Poly(LSL) as a material.  相似文献   

    

Christoph Schoo  Sebastian Bestgen  Alexander Egeberg  Jasmin Seibert  Sergey N. Konchenko  Claus Feldmann  Peter W. Roesky 《Angewandte Chemie (International ed. in English)》2019,58(13):4386-4389

Zintl phases of arsenic and molecular compounds containing Zintl‐type polyarsenide ions are of fundamental interest in basic and applied sciences. Unfortunately, the most obvious and reactive arsenic source for the preparation of defined molecular polyarsenide compounds, yellow arsenic As₄, is very inconvenient to prepare and neither storable in pure form nor easy to handle. Herein, we present the synthesis and reactivity of elemental As⁰ nanoparticles (As⁰_Nano, d=7.2±1.8 nm), which were successfully utilized as a reactive arsenic source in reductive f‐element chemistry. Starting from [Cp*₂Sm] (Cp*=η⁵‐C₅Me₅), the samarium polyarsenide complexes [(Cp*₂Sm)₂(μ‐η²:η²‐As₂)] and [(Cp*₂Sm)₄As₈] were obtained from As⁰_nano, thereby generating the largest molecular polyarsenide of the f‐elements and circumventing the use of As₄ in preparative chemistry.  相似文献   

    

Tobias Baumann  Matthias Hauf  Fabian Schildhauer  Katharina B. Eberl  Patrick M. Durkin  Erhan Deniz  Jan G. Lffler  Carlos G. Acevedo‐Rocha  Jelena Jaric  Berta M. Martins  Holger Dobbek  Jens Bredenbeck  Nediljko Budisa 《Angewandte Chemie (International ed. in English)》2019,58(9):2899-2903

Allosteric information transfer in proteins has been linked to distinct vibrational energy transfer (VET) pathways in a number of theoretical studies. Experimental evidence for such pathways, however, is sparse because site‐selective injection of vibrational energy into a protein, that is, localized heating, is required for their investigation. Here, we solved this problem by the site‐specific incorporation of the non‐canonical amino acid β‐(1‐azulenyl)‐l ‐alanine (AzAla) through genetic code expansion. As an exception to Kasha's rule, AzAla undergoes ultrafast internal conversion and heating after S₁ excitation while upon S₂ excitation, it serves as a fluorescent label. We equipped PDZ3, a protein interaction domain of postsynaptic density protein 95, with this ultrafast heater at two distinct positions. We indeed observed VET from the incorporation sites in the protein to a bound peptide ligand on the picosecond timescale by ultrafast IR spectroscopy. This approach based on genetically encoded AzAla paves the way for detailed studies of VET and its role in a wide range of proteins.  相似文献