Trichalcogenasupersumanenes and its concave-convex supramolecular assembly with fullerenes.

Synthesis of buckybowls have stayed highly challenging due to the large structural strain caused by curved π surface. In this paper, we report the synthesis and properties of two trichalcogenasupersumanenes which three chalcogen (sulfur or selenium) atoms and three methylene groups bridge at the bay regions of hexa-peri-hexabenzocoronene. These trichalcogenasupersumanenes are synthesized quickly in three steps using an Aldol cyclotrimerization, a Scholl oxidative cyclization, and a Stille type reaction. X-ray crystallography analysis reveals that they encompass bowl diameters of 11.06 Å and 11.35 Å and bowl depths of 2.29 Å and 2.16 Å for the trithiasupersumanene and triselenosupersumanene, respectively. Furthermore, trithiasupersumanene derivative with methyl chains can form host-guest complexes with C60 or C70, which are driven by concave-convex π ⋯ π interactions and multiple C-H ⋯ π interactions between bowl and fullerenes.

A contorted nanographene shelter.

Nanographenes have kindled considerable interest in the fields of materials science and supramolecular chemistry as a result of their unique self-assembling and optoelectronic properties. Encapsulating the contorted nanographenes inside artificial receptors, however, remains challenging. Herein, we report the design and synthesis of a trigonal prismatic hexacationic cage, which has a large cavity and adopts a relatively flexible conformation. It serves as a receptor, not only for planar coronene, but also for contorted nanographene derivatives with diameters of approximately 15 Å and thicknesses of 7 Å. A comprehensive investigation of the host-guest interactions in the solid, solution and gaseous states by experimentation and theoretical calculations reveals collectively an induced-fit binding mechanism with high binding affinities between the cage and the nanographenes. Notably, the photostability of the nanographenes is improved significantly by the ultrafast deactivation of their excited states within the cage. Encapsulating the contorted nanographenes inside the cage provides a noncovalent strategy for regulating their photoreactivity.

1,2,5,6,9-Pentaazacoronenes (PACs) and π-Extended PAC Derivatives: Synthesis, Crystal Structure, and Optical and Redox Properties.

A novel class of 1,2,5,6,9-pentaazacoronene (PAC, 1) derivatives and π-extended PAC derivatives, chromeno[2,3,4-ij]pentaazacoronenes (CPACs, 2), has been successfully synthesized on the basis of intramolecular diazo-coupling reaction and Pictet-Spengler cyclization. Single-crystal analysis demonstrates that 1o (R1 = H) displays a herringbone packing motif while 1s (R1 = C3F7) packs into an S-shaped arrangement. Photophysical and electrochemical studies indicated that the new PAC system manifested significantly red-shifted absorption and emission capacity, larger Stokes shifts, and narrower HOMO-LUMO energy gaps.

A Polyaromatic Nano-nest for Hosting Fullerenes C60 and C70.

A "Janus" type of hexa- cata-hexabenzocoronene with three triptyceno subunits fused symmetrically on the periphery of coronene has been synthesized using a covalent self-assembly strategy. The triptyceno subunits form a nanosized nest on one side of the aromatic plane with space-matching fullerenes such as C60 and C70 to afford shape-complementary supramolecular complexes. The formation of the complexes in solution was confirmed by 1H NMR and fluorescence titration. Four complexes with C60 or C70 were obtained and studied by single-crystal X-ray diffraction analysis. In the crystal structure, the host shows a proper tunability to adjust its conformation in accordance with the shape of the guest. The different stoichiometric ratios and various stacking patterns of the complexes suggest the diversity of this nonplanar polyaromatic host in complexation with fullerenes.