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A cyclophane is reported incorporating two units of a heptagon‐containing extended polycyclic aromatic hydrocarbon (PAH) analogue of the hexa‐peri‐hexabenzocoronene (HBC) moiety (hept‐HBC). This cyclophane represents a new class of macrocyclic structures that incorporate for the first time seven‐membered rings within extended PAH frameworks. The saddle curvature of the hept‐HBC macrocycle units induced by the presence of the nonhexagonal ring along with the flexible alkyl linkers generate a cavity with shape complementarity and appropriate size to enable π interactions with fullerenes. Therefore, the cyclophane forms host–guest complexes with C60 and C70 with estimated binding constants of Ka=420±2 m−1 and Ka=(6.49±0.23)×103 m−1, respectively. As a result, the macrocycle can selectively bind C70 in the presence of an excess of a mixture of C60 and C70. [ABSTRACT FROM AUTHOR]

A new family of distorted ribbon‐shaped nanographenes was designed, synthesized, and their optical and electrochemical properties were evaluated, pointing out an unprecedented correlation between their structural characteristics and the two‐photon absorption (TPA) responses and electrochemical band gaps. Three nanographene ribbons have been prepared: a seven‐membered‐ring‐containing nanographene presenting a tropone moiety at the edge, its full‐carbon analogue, and a purely hexagonal one. We have found that the TPA cross‐sections and the electrochemical band gaps of the seven‐membered‐ring‐containing compounds are higher and lower, respectively, than those of the fully hexagonal polycyclic aromatic hydrocarbon (PAH). Interestingly, the inclusion of additional curvature has a positive effect in terms of non‐linear optical properties of those ribbons. [ABSTRACT FROM AUTHOR]

A unique rippled nanographene consisting of 52 fused rings is presented in which six out‐of‐plane motifs are fully fused into a triangular aromatic surface with a size of approximately 2.5 nm. Three units of an unprecedented fully lateral π‐extended octabenzo[5]helicene together with three units of saddle‐shaped heptagonal rings are combined in a single structure, leading to a well‐soluble warped nanographene. The two diastereomeric pairs of possible enantiomers were isolated, and their linear, non‐linear, and chiroptical properties were evaluated, revealing outstanding quantum yield and brightness values at low energy, together with good chiroptical responses in both absorption and emission. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of an enantiopure superhelicene nanographene is reported in which two saddle‐shaped and one planar hexabenzocoronene (HBC) units are arranged in a helicoidal shape to form an undecabenzo[7]carbohelicene. The described compound is the first fully π‐extended [7]helicene. Racemic resolution of the helical nanographene permitted analysis of the chiroptical properties and revealed dissymmetry factors in the range of 2×10−3 both in the absorption and in the emission measurements. Remarkably, non‐linear photophysical analysis demonstrated a two‐photon absorption cross‐section of 870 GM at 800 nm and a perfect overlap between linear, non‐linear, and chiral emissions. A twist in the ribbon: A chiral helical nanographene with a central [7]helicene unit was synthesized and its enantiomers isolated and studied. Both enantiomers of the undecabenzo[7]superhelicene exhibit remarkable chiroptical and non‐linear optical properties, with a two‐photon absorption cross‐section of 870 GM at 800 nm and a perfect overlap between linear, non‐linear, and chiral emissions. CPL=circularly polarized luminescence. [ABSTRACT FROM AUTHOR]

A new family of homochiral silver complexes based on carbophilic interactions with ortho-phenylene ethynylene (o-OPE) scaffolds containing up to two silver atoms are described. These compounds represent a unique class of complexes with chirality at the metal. Chiral induction is based on the inclusion of chiral sulfoxides, which allow efficient transfer of chirality to the helically folded o-OPE, leading to circularly polarized luminescence (CPL)- and vibrational circular dichroism (VCD)-active compounds. In the presence of silver(I) cations, carbophilic interactions dominate, which promote helical structures with a defined helicity. This is one of the very scarce examples of the use of such interactions in the attractive field of abiotic foldamers. The switching event has been extensively studied by using different chiroptical techniques, including circular dichroism, CPL, and VCD, and represents one of the few CPL switches described in the literature. [ABSTRACT FROM AUTHOR]

Abstract: A new family of homochiral silver complexes based on carbophilic interactions with ortho‐phenylene ethynylene (o‐OPE) scaffolds containing up to two silver atoms are described. These compounds represent a unique class of complexes with chirality at the metal. Chiral induction is based on the inclusion of chiral sulfoxides, which allow efficient transfer of chirality to the helically folded o‐OPE, leading to circularly polarized luminescence (CPL)‐ and vibrational circular dichroism (VCD)‐active compounds. In the presence of silver(I) cations, carbophilic interactions dominate, which promote helical structures with a defined helicity. This is one of the very scarce examples of the use of such interactions in the attractive field of abiotic foldamers. The switching event has been extensively studied by using different chiroptical techniques, including circular dichroism, CPL, and VCD, and represents one of the few CPL switches described in the literature. [ABSTRACT FROM AUTHOR]

Innenrücktitelbild: Two-Photon Absorption Enhancement by the Inclusion of a Tropone Ring in Distorted Nanographene Ribbons (Angew. Keywords: carbon materials; graphene; helicenes; nanostructures; nonlinear optics EN carbon materials graphene helicenes nanostructures nonlinear optics 7338 7338 1 04/22/20 20200427 NES 200427 B Strukturdefekte b sind ein möglicher Schlüssel für Fortschritte in der Nanographen-Technologie. E. Maçôas, A. G. Campaña et al. zeigen in ihrem Forschungsartikel auf S. 7205, wie die Einführung eines Carbonyl-substituierten heptagonalen Rings (Tropon) in ein Nanographenband die Effizienz der Upconversion-Emission bei Zweiphotonenanregung im Vergleich zu einem defektfreien Analogon erhöht. [Extracted from the article]