0000000000037963
AUTHOR
Yunbin Hu
Dicyclopentaannelated Hexa-peri-hexabenzocoronenes with a Singlet Biradical Ground State
Abstract Synthesis of two dicyclopentaannelated hexa‐peri‐hexabenzocoronene (PHBC) regioisomers was carried out, using nonplanar oligoaryl precursors with fluorenyl groups: mPHBC 8 with two pentagons in the “meta”‐configuration was obtained as a stable molecule, while its structural isomer with the “para”‐configuration, pPHBC 16, could be generated and characterized only in situ due to its high chemical reactivity. Both PHBCs exhibit low energy gaps, as reflected by UV‐vis‐NIR absorption and electrochemical measurements. They also show open‐shell singlet ground states according to electron paramagnetic resonance (EPR) measurements and density functional theory (DFT) calculations. The use of…
π-Extended Pyrene-Fused Double [7]Carbohelicene as a Chiral Polycyclic Aromatic Hydrocarbon
A π-extended double [7]carbohelicene 2 with fused pyrene units was synthesized, revealing considerable intra- and intermolecular π–π interactions as confirmed with X-ray crystallography. As compared to the previous double [7]carbohelicene 1, the π-extended homologue 2 demonstrated considerably red-shifted absorption with an onset at 645 nm (1: 550 nm) corresponding to a smaller optical gap of 1.90 eV (1: 2.25 eV). A broad near-infrared emission from 600 to 900 nm with a large Stokes shift of ∼100 nm (2.3 × 103 cm–1) was recorded for 2, implying formation of an intramolecular excimer upon excitation, which was corroborated with femtosecond transient absorption spectroscopy. Moreover, 2 revea…
Negatively Curved Nanographene with Heptagonal and [5]Helicene Units
Negatively curved nanographene (NG) 4, having two heptagons and a [5]helicene, was unexpectedly obtained by aryl rearrangement and stepwise cyclodehydrogenations. X-ray crystallography confirmed the saddle-shaped structures of intermediate 3 and NG 4. The favorability of rearrangement over helicene formation following radical cation or arenium cation mechanisms is supported by theoretical calculations. NG 4 demonstrates a reversible mechanochromic color change and solid-state emission, presumably benefiting from its loose crystal packing. After resolution by chiral high-performance liquid chromatography, the circular dichroism spectra of enantiomers 4-(P) and 4-(M) were measured and showed …
Benzo-Fused Periacenes or Double Helicenes? Different Cyclodehydrogenation Pathways on Surface and in Solution
Controlling the regioselectivity of C-H activation in unimolecular reactions is of great significance for the rational synthesis of functional graphene nanostructures, which are called nanographenes. Here, we demonstrate that the adsorption of tetranaphthyl- p-terphenyl precursors on metal surfaces can completely change the cyclodehydrogenation route and lead to obtaining planar benzo-fused perihexacenes rather than double [7]helicenes during solution synthesis. The course of the on-surface planarization reactions is monitored using scanning probe microscopy, which unambiguously reveals the formation of dibenzoperihexacenes and the structures of reaction intermediates. The regioselective pl…
Amplification of Dissymmetry Factors in π-Extended [7]- and [9]Helicenes
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…
Spiro-fused bis-hexa-peri-hexabenzocoronene.
A spiro-fused hexa-peri-hexabenzocoronene dimer was synthesized, and its physicochemical properties were studied by UV-Vis absorption and emission spectroscopy as well as cyclic voltammetry. Chemical oxidation of SB-HBC afforded its radical cation and dication derivatives, which could be reversibly reduced to the neutral state.
CCDC 2047542: Experimental Crystal Structure Determination
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 2004421: Experimental Crystal Structure Determination
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
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 2047540: Experimental Crystal Structure Determination
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 1914718: Experimental Crystal Structure Determination
Related Article: Yunbin Hu, Giuseppe M. Paternò, Xiao-Ye Wang, Xin-Chang Wang, Michele Guizzardi, Qiang Chen, Dieter Schollmeyer, Xiao-Yu Cao, Giulio Cerullo, Francesco Scotognella, Klaus Müllen, Akimitsu Narita|2019|J.Am.Chem.Soc.|141|12797|doi:10.1021/jacs.9b05610
CCDC 2004419: Experimental Crystal Structure Determination
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
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 2004420: Experimental Crystal Structure Determination
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 1848515: Experimental Crystal Structure Determination
Related Article: Yunbin Hu, Di Wang, Martin Baumgarten, Dieter Schollmeyer, Klaus Müllen, Akimitsu Narita|2018|Chem.Commun.|54|13575|doi:10.1039/C8CC07405D