Bowl-shaped π-conjugated compounds offer the possibility to study curvature-dependent host-guest interactions and chemical reactivity in ideal model systems. For surface-adsorbed π bowls, however, only conformations with the bowl opening pointing away from the surface have been observed so far. Here we show for sumanene on Ag(111) that both bowl-up and bowl-down conformations can be stabilized. Analysis of the molecular layer as a function of coverage reveals an unprecedented structural phase transition involving a bowl inversion of one-third of the molecules. On the basis of scanning tunneling microscopy (STM) and complementary atomistic simulations, we develop a model that describes the observed phase transition in terms of a subtle interplay between inversion-dependent adsorption energies and intermolecular interactions. In addition, we explore the coexisting bowl-up and -down conformations with respect to host-guest binding of methane. STM reveals a clear energetic preference for methane binding to the concave face of sumanene.
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http://dx.doi.org/10.1021/ja504126z | DOI Listing |
Chem Sci
November 2024
Department of Organic Chemistry, Universidad Autónoma de Madrid Madrid 28049 Spain
Chiral conjugated materials with curved topologies hold significant promise for advanced optoelectronic applications. Among these, bowl-shaped subphthalocyanine (SubPc) aromatics are particularly noteworthy due to their superb optoelectronic properties and synthetic versatility. Despite their potential, the development and application of inherently chiral SubPcs as functional materials have been hampered by the scalability and feasibility limitations of current high-performance liquid chromatography methods.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
State Key Laboratory for Physical Chemistry of Solid Surfaces, iChEM (Collaborative Innovation Center of Chemistry for Energy Materials), Department of Chemistry, Xiamen University, Xiamen, 361005, China.
Herein, corannulene-based quintuple [6]helicenes (Q[6]H-1 and Q[6]H-2) and [7]helicene (Q[7]H) were synthesized via penta-fold Heck and Mallory reaction. Notably, Q[7]H represents the highest reported helicene based on corannulene. X-ray crystallography reveals that Q[6]H-2 adopts a propeller-shaped conformation with a well-preserved corannulene core, while Q[6]H-1 and Q[7]H exhibit quasi-propeller-shaped conformations.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, P. R. China.
Tetracene and pentacene are large, promising building blocks for construction of complex molecular nanocarbons due to their extraordinary photophysical and electronic properties. Herein, two acene-integrated buckybowls, composed of two rows of tetracenes and pentacenes fused through s-indacene unit at the zigzag edges, have been synthesized and characterized. Compared to parent tetracene and pentacene, the buckybowls are extremely stable and show much smaller electrochemical band gaps.
View Article and Find Full Text PDFAromatic system extension of corannulene (Cor) is a synthetic challenge to access non-planar polyaromatic hydrocarbons (PAHs). Herein, we report the design and synthesis of azaborahelicene corannulene 1 through hybridization of an azabora[5] helical structure and subsequent luminescence studies. Significant enhancement in chemiluminescence (CL), electroluminescence (ECL) and photoluminescence (PL) is achieved compared to those of pristine Cor.
View Article and Find Full Text PDFChemistry
August 2024
Department of Physical Science and Materials Engineering, Iwate University, 4-3-5 Ueda, Morioka, 020-8551, Japan.
Kekulene, a cycloarene composed of 12 fused benzene rings in a circular arrangement, exhibits a highly planar and robust structure. Kekulene has been the subject of investigation into its aromaticity and electronic structure, particularly in relation to the cyclic benzenoid. We have successfully synthesized novel bowl-shaped kekulene analogues with five-membered rings incorporated into the kekulene structure.
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