A Cycloparaphenylene Acetylene as Potential Precursor for an Armchair Carbon Nanotube.

The bottom-up synthesis of carbon nanotubes (CNTs) is a long-standing goal in synthetic chemistry. Producing CNTs with defined lengths and diameters would render these materials and thus their fascinating properties accessible in a controlled way. Inspired by a recently reported synthesis of armchair graphene sheets that relied on a benzannulation and Scholl oxidation of a poly(p-phenylene ethynylene), the same strategy is applied on a cyclic substrate with a short, but well defined CNT as target structure.

Redox-Switchable Aromaticity in a Helically Extended Indeno[2,1-]fluorene.

Molecular switches have received major attention to enable the reversible modulation of various molecular properties and have been extensively used as trigger elements in diverse fields, including molecular machines, responsive materials, and photopharmacology. Antiaromaticity is a fascinating property that has attracted not only significant fundamental interest but is also increasingly relevant in different applications, in particular organic (opto)electronics. However, designing systems in which (anti)aromaticity can be judiciously and reversibly switched ON and OFF remains challenging.

Circularly Polarized Luminescence of Thiophene-Bridged Macrocyclic pseudo-meta [2.2]Paracyclophanes.

Chiral organic molecules possessing high quantum yields, circular dichroism, and circularly polarized luminescence values have great potential as optically active materials for future applications. Recently, the identification of a promising class of inherently chiral compounds was reported, namely macrocyclic 1,3-butadiyne-linked pseudo-meta[2.2]paracyclophanes, displaying high circular dichroism and related g values albeit modest quantum yields.

Intense Molar Circular Dichroism in Fully Conjugated All-Carbon Macrocyclic 1,3-Butadiyne Linked pseudo-meta [2.2]Paracyclophanes.

Invited for the cover of this issue is the group of Marcel Mayor at the University of Basel with co-workers Olaf Fuhr and Dieter Fenske from Karlsruhe Institute of Technology. The image depicts the studied all-carbon polygon shaped macrocycles along with their intense circular dichroism spectra in the background. The bright light within the macrocycles displays its efficient conjugation.

Intense Molar Circular Dichroism in Fully Conjugated All-Carbon Macrocyclic 1,3-Butadiyne Linked pseudo-meta [2.2]Paracyclophanes.

The synthetic access to macrocyclic molecular topologies with interesting photophysical properties has greatly improved thanks to the successful implementation of organic and inorganic corner units. Based on recent reports, we realized that pseudo-meta [2.2]paracyclophanes (PCPs) might serve as optimal corner units for constructing 3D functional materials, owing to their efficient electronic communication, angled substituents and planar chirality.

Induced axial chirality by a tight belt: naphthalene chromophores fixed in a 2,5-substituted cofacial -phenylene-ethynylene framework.

We report the design of a synthetically easy accessible axial chirality-inducing framework for a chromophore of choice. The scaffold consists of two basic -phenylene-ethynylene backbones separated by laterally placed corner units. Substitution with an inherently achiral chromophore at the 2 and 5 positions of the central phenylene excitonically couples the chromophore associated transition and thereby results in chiroptical properties.

Helicene Monomers and Dimers: Chiral Chromophores Featuring Strong Circularly Polarized Luminescence.

The synthesis and chiroptical properties of a series of enantiomerically pure, C -symmetrical carbo[6]helicene dimers are reported. Two helicene cores are connected through a buta-1,3-diyne-1,4-diyl linker or a heteroaromatic bridge and bear arylethynyl substituents at their 15-positions. This ensures the possibility of extended electronic communication throughout the whole molecule.

Helical Threads: Enantiomerically Pure Carbo[6]Helicene Oligomers.

We report the synthesis of enantiomerically pure carbo[6]helicene oligomers with buta-1,3-diyne-1,4-diyl bridges between the helicene nuclei. The synthesis of monomeric (±)-2,15-bis[(triisopropylsilyl)ethynyl]carbo[6]helicene was achieved in 25 % yield over six steps. Pure (+)-(P)- and (-)-(M)-enantiomers were obtained by HPLC on a chiral stationary phase.