Search results for "Helicene"
showing 10 items of 16 documents
Synthesis and structural properties of hexaaza[5]helicene containing two [1,2,3]triazolo[1,5-a]pyridine moieties
2013
Abstract We have synthesized a novel hexaaza[5]helicene in a straightforward way from neocuproine. The crystal structure has been elucidated with direct-space strategy TALP which demonstrates the power of the powder X-ray diffraction technique. In this crystal structure it is possible to see an interplanar angle of 33(1)° between the two triazolopyridine rings. The centrosymmetric crystal structure is a racemic mixture, but the resolution was not possible due to a ring-chain isomerization in a solution that produces a dynamic racemization.
CCDC 1882076: Experimental Crystal Structure Determination
2019
Related Article: Sebastian B. Beil, Peter Franzmann, Timo Müller, Maximilian M. Hielscher, Tobias Prenzel, Dennis Pollok, Nicole Beiser, Dieter Schollmeyer, Siegfried R. Waldvogel|2018|Electrochimica Acta|302|310|doi:10.1016/j.electacta.2019.02.041
Novel [6]- and [7]Helicene-Like Quinones via Mono- and Bidirectional Chromium-Templated Benzannulation of Bridged Binaphthyl Carbene Complexes
2005
A new organometallic approach to novel, functionalised, helicene-like quinones and bisquinones has been developed based on the chromium-templated [3+2+1] benzannulation reaction. The [5]helicene-analogous monocarbene chromium complexes 4, 5, 17 and 19, derived from dibromo-substituted methylene- or silylene-tethered binaphthols 2 and 3, react with various alkynes to give [6]helicene-like quinones 6–13 and 20–29 after oxidative work-up. A rare competition of angular vs. linear annulation is observed for the incorporation of phenylacetylene that affords quinones 21/22 and 28/29. Protection of the phenolic benzannulation product with camphanic acid chloride 14, followed by chromatographic sepa…
A theoretical and experimental study of the racemization process of hexaaza[5]helicenes
2014
A dynamic 1H NMR study, together with DFT calculations, of bis-([1,2,3]triazolo)[1,5-a:5′,1′-k][1,10]phenanthroline 2 has allowed to identify the ring and open forms of a new example of ring/chain tautomerism, as well as their interconversion barriers (ring/ring and ring/open). The barrier of the exchange process between the chain forms and the ring form was found higher than the 'racemization' process in the closed form, so the ring opening does not contribute to the 'racemization'. The di-1,10-methyl and di-1,10-iodo derivatives have been prepared and their properties calculated.
Amplification of Dissymmetry Factors in π-Extended [7]- and [9]Helicenes
2021
International audience; $\pi$-Extended helicenes constitute an important class of polycyclic aromatic hydrocarbons with intrinsic chirality. Herein, we report the syntheses of $\pi$extended [7]helicene $4$ and $\pi$-extended [9]helicene $6$ through regioselective cyclodehydrogenation in high yields, where a "prefusion" strategy plays a key role in preventing undesirable aryl rearrangements. The unique helical structures are unambiguously confirmed by X-ray crystal structure analysis. Compared to the parent pristine [7]helicene and [9]helicene, these novel $\pi$-extended helicenes display significantly improved photophysical properties, with a quantum yield of 0.41 for $6$. After optical res…
CCDC 146055: Experimental Crystal Structure Determination
2000
Related Article: H.Meier, M.Schwertel, D.Schollmeyer|2000|Acta Crystallogr.,Sect.C:Cryst.Struct.Commun.|56|684|doi:10.1107/S0108270100003140
CCDC 2004421: Experimental Crystal Structure Determination
2020
Related Article: Zijie Qiu, Sobi Asako, Yunbin Hu, Cheng-Wei Ju, Thomas Liu, Loïc Rondin, Dieter Schollmeyer, Jean-Sébastien Lauret, Klaus Müllen, Akimitsu Narita|2020|J.Am.Chem.Soc.|142|14814|doi:10.1021/jacs.0c05504
CCDC 2021692: Experimental Crystal Structure Determination
2020
Related Article: Zijie Qiu, Sobi Asako, Yunbin Hu, Cheng-Wei Ju, Thomas Liu, Loïc Rondin, Dieter Schollmeyer, Jean-Sébastien Lauret, Klaus Müllen, Akimitsu Narita|2020|J.Am.Chem.Soc.|142|14814|doi:10.1021/jacs.0c05504
CCDC 2047541: Experimental Crystal Structure Determination
2021
Related Article: Zijie Qiu, Cheng-Wei Ju, Lucas Frédéric, Yunbin Hu, Dieter Schollmeyer, Grégory Pieters, Klaus Müllen, Akimitsu Narita|2021|J.Am.Chem.Soc.|143|4661|doi:10.1021/jacs.0c13197
CCDC 146054: Experimental Crystal Structure Determination
2000
Related Article: H.Meier, M.Schwertel, D.Schollmeyer|2000|Acta Crystallogr.,Sect.C:Cryst.Struct.Commun.|56|684|doi:10.1107/S0108270100003140