13029-09-9Relevant articles and documents
A silicon-heteroaromatic system as photosensitizer for light-driven hydrogen production by hydrogenase mimics
Goy, Roman,Apfel, Ulf-Peter,Elleouet, Catherine,Escudero, Daniel,Elstner, Martin,Goerls, Helmar,Talarmin, Jean,Schollhammer, Philippe,Gonzalez, Leticia,Weigand, Wolfgang
, p. 4466 - 4472 (2013)
The utilization of light and inexpensive catalysts to afford hydrogen represents a huge challenge. Following our interest in silicon-containing [FeFe]-hydrogenase ([FeFe]-H2ase) mimics, we report a new model approach for a photocatalytic [FeFe]-H2ase mimic 1, which contains a 1-silafluorene unit as a photosensitizer. Thereby, the photoactive ligand is linked to the [2Fe2S] cluster through S-CH2-Si bridges. Photochemical H2 evolution experiments were performed and revealed a turnover number (TON) of 29. This is the highest reported photocatalytic efficiency for an [FeFe]-H2ase model complex in which the photosensitizer is covalently linked to the catalytic center. We report a viable synthetic pathway for the construction of a new photoactive model of the [FeFe]-hydrogenase ([FeFe]-H2ase) active site with a dithiolate bridge and 1-silafluorene as a photosensitizer. The [FeFe]-H2ase mimic represents a very compact, easily accessible, and inexpensive photocatalyst for hydrogen generation. Copyright
Transition-Metal-Free Approach for the Direct Arylation of Thiophene: Experimental and Theoretical Investigations towards the (Het)-Aryne Route
Demangeat, Catherine,Saied, Tarak,Ramozzi, Romain,Ingrosso, Francesca,Ruiz-Lopez, Manuel,Panossian, Armen,Leroux, Frédéric R.,Fort, Yves,Comoy, Corinne
, p. 547 - 556 (2019)
This paper presents the results of our investigations on the arylation of thiophene using the transition-metal-free “aryne coupling” methodology. The reaction was studied by both experiment and computation (density functional theory) and comparison with phenyllithium was established. In parallel, the effects of the ligand and the salt on the coupling reaction were examined. The results underline the remarkable effect of such additives on the coupling reaction and the potency of the method to construct hetaryl–aryl backbones which open up promising access to a wide range of heterobiaryl structures using the novel “Het-Aryne” route.
REGIOSELECTIVE DIMETALLIERUNG VON AROMATEN. BEQUEMER ZUGANG ZU 2,2'-DISUBSTITUIERTEN BIPHENYLDERIVATEN
Neugebauer, Wolfgang,Kos, Alexander J.,Schleyer, Rague
, p. 107 - 118 (1982)
Lithiation of biphenyl with 2.4 mol of n-butyllithium in the presence of TMEDA led directly to the 2,2'-dilithio derivative (I) in modest, but preparatively useful yields.I, in turn, was converted to a variety of products.The activation of the 2'-position of 2-lithiobiphenyl was shown directly by a separate experiment.MNDO calculations indicate stabilization in I by double bridging and in 2-lithiobiphenyl by intramolecular ? interaction of Li with the o-phenyl group.Similar interactions in substitution transition states rationalize the specificity of the reactions observed.
Direct Observation of Aggregation-Induced Emission Mechanism
Corminboeuf, Clémence,Guan, Jianxin,Han, Han,Lin, Kun-Han,Liu, Jitian,Peng, Jie,Prlj, Antonio,Wei, Rong,Yu, Zhihao,Zhao, Dahui,Zheng, Junrong
, p. 14903 - 14909 (2020)
The mechanism of aggregation-induced emission, which overcomes the common aggregation-caused quenching problem in organic optoelectronics, is revealed by monitoring the real time structural evolution and dynamics of electronic excited state with frequency and polarization resolved ultrafast UV/IR spectroscopy and theoretical calculations. The formation of Woodward–Hoffmann cyclic intermediates upon ultraviolet excitation is observed in dilute solutions of tetraphenylethylene and its derivatives but not in their respective solid. The ultrafast cyclization provides an efficient nonradiative relaxation pathway through crossing a conical intersection. Without such a reaction mechanism, the electronic excitation is preserved in the molecular solids and the molecule fluoresces efficiently, aided by the very slow intermolecular charge and energy transfers due to the well separated molecular packing arrangement. The mechanisms can be general for tuning the properties of chromophores in different phases for various important applications.
Pd(OAc)2/PPh3-catalyzed desulfonylative homocoupling of arylsulfonyl chlorides
Zhao, Qiao,Chen, Liangshun,Lang, Hongyue,Wu, Shengying,Wang, Limin
, p. 535 - 538 (2015)
The Pd-catalyzed homodimerization with respect to arylsulfonyl chlorides as an efficient method for the synthesis of biaryls has been developed. This desulfonylative reaction which was performed at reflux in 1,4-dioxane for 4 h under air afforded the desired products in good to excellent yields. The Pd(OAc)2/PPh3-catalyzed desulfonylative homodimerization of arenesulfonyl chlorides as an efficient method for the synthesis of biaryls was described. The corresponding products were obtained in good to excellent yields.
ortho-Phenylene-Based Macrocyclic Hydrocarbons Assembled Using Olefin Metathesis
Hartley, C. Scott,Kirinda, Viraj C.,Schrage, Briana R.,Ziegler, Christopher J.
, (2020)
While many foldamer systems reliably fold into well-defined secondary structures, higher order structure remains a challenge. A simple strategy for the organization of folded subunits in space is to link them together within a macrocycle. Previous work has shown that o-phenylenes can be co-assembled with rod-shaped linkers into twisted macrocycles, showing an interesting synergy between folding and thermodynamically controlled macrocyclization. In these systems the foldamer units were largely decoupled from each other both conformationally and electronically. Here, we show that hydrocarbon macrocycles, with very short ethenylene linkers, can be assembled from o-phenylenes using olefin metathesis. Characterization by NMR spectroscopy, X-ray crystallography, and ab initio calculations shows that the products are approximately triangular trimer macrocycles with helical o-phenylene corners in a heterochiral configuration. Their photophysics are dominated by the 4,4'-diphenylstilbene moieties, the longest conjugated segments, with further conjugation broken by the twisting of the o-phenylenes.
Silicon-Heteroaromatic [FeFe] Hydrogenase Model Complexes: Insight into Protonation, Electrochemical Properties, and Molecular Structures
Goy, Roman,Bertini, Luca,G?rls, Helmar,De Gioia, Luca,Talarmin, Jean,Zampella, Giuseppe,Schollhammer, Philippe,Weigand, Wolfgang
, p. 5061 - 5073 (2015)
To learn from Nature how to create an efficient hydrogen-producing catalyst, much attention has been paid to the investigation of structural and functional biomimics of the active site of [FeFe]-hydrogenase. To understand their catalytic activities, the μ
Convenient One-Pot Synthesis of 9 H -Carbazoles by Microwave Irradiation Employing a Green Palladium-Based Nanocatalyst
Steingruber, H. Sebastián,Mendioroz, Pamela,Volpe, María A.,Gerbino, Darío C.
, p. 4048 - 4058 (2021/08/03)
An efficient palladium-catalyzed tandem reaction for the one-pot synthesis of 9 H -carbazoles under microwave irradiation is developed. This approach involves a sequential Buchwald-Hartwig amination and a direct arylation from affordable and inexpensive anilines and 1,2-dihaloarenes. For the development of this purpose, a novel and magnetically recoverable palladium nanocatalyst supported on a green biochar under ligand-free conditions is used. Compared to other existing palladium-based protocols, the present synthetic methodology shows a drastic reduction in reaction times and excellent compatibility with different functional groups allowing to obtain a small library of 9 H -carbazoles in high yields and with good regioselectivity. This procedure represents the first example in the direct synthesis of carbazoles using a heterogeneous palladium nanocatalyst from commercial precursors. To examine the application of this protocol, a direct and scalable synthesis of the bioactive carbazole alkaloid clausenalene from commercially available starting materials is described.