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Atomically-defined graphene nanoribbons (GNRs), which are narrow strips of graphene that feature a quantum confinement-induced bandgap, have shown great promise for applications in the next generation of semiconductor devices. Although numerous studies have demonstrated the bottom-up synthesis of all-carbon GNRs, a comparatively limited number of reports have focused on the preparation of nitrogen-doped GNRs, with two general types of architectures demonstrated to date. Herein, we describe the design, synthesis, and characterization of a new class of nitrogen-containing GNRs consisting of repeating tetrabenzopentacene molecular subunits. Our findings may afford additional possibilities and opportunities with regard to the directed bottom-up synthesis of heteroatom-doped, carbon-based nanoscale electronics. (C) 2020 Elsevier Ltd. All rights reserved.

The chemoselectivity of molecular catalysts underpins much of modern synthetic organic chemistry. However, little is known about the selectivity of individual catalysts because this single-catalyst-level behavior is hidden by the bulk catalytic behavior. Here, for the first time, the selectivity of individual molecular catalysts for two different reactions is imaged in real time at the single-catalyst level. This imaging is achieved through fluorescence microscopy paired with spectral probes that produce a snapshot of the instantaneous chemoselectivity of a single catalyst for either a single-chain-elongation or a single-chain-termination event during ruthenium-catalyzed polymerization. Superresolution imaging of multiple selectivity events, each at a different single-molecular ruthenium catalyst, indicates that catalyst selectivity may be unexpectedly spatially and time-variable.

Perylene-3,4,9,10-tetracarboxylic diimides (PTCDIs) have been extensively studied for organic electronics applications. Additionally, PTCDI-based supramolecular architectures have been used as platforms for the investigation of various charge transfer/transport phenomena. For these systems, the study of their structural characteristics and self-assembly behavior with molecular dynamics simulations has remained relatively limited. Herein, we describe a detailed molecular dynamics investigation of the intramolecular self-assembly of DNA-inspired columnar macromolecules, which consist of multiple hexaethyleneglycol-substituted PTCDIs that are covalently appended to a phosphoalkane backbone. By evaluating relevant geometric and energetic parameters obtained from our simulations, we determine the factors underpinning the dynamics of PTCDI stacking for our constructs. Our findings may shed insight into the structure of biomimetic one-dimensional molecular wires from PTCDIs and other related materials.

This study describes the synthesis of modular diquinolineanthracene and polydiquinolineanthracene derivatives. The reported facile and scalable aza-Diels-Alder-based approach requires mild conditions, proceeds in two steps, uses commercially available starting materials, and accommodates varying functionalities. Given the known utility of the acene and quinoline motifs, the synthesized molecules and polymers hold promise for organic electronics applications.

Carbon-based materials, such as acenes, fullerenes, and graphene nanoribbons, are viewed as the potential successors to silicon in the next generation of electronics. Although a number of methodologies provide access to these materials' all-carbon variants, relatively fewer strategies readily furnish their nitrogen-doped analogues. Herein, we report the rational design, preparation, and characterization of nitrogen-containing rubicenes and tetrabenzopentacenes, which can be viewed either as acene derivatives or as molecular fragments of fullerenes and graphene nanoribbons. The reported findings may prove valuable for the development of electron transporting organic semiconductors and for the eventual construction of larger carbonaceous systems.

Polyquinolines have attracted attention as functional materials due to their excellent combination of optical, electrical, chemical, thermal, and mechanical properties. However, only a handful of synthetic routes for the preparation of these polymers have been established to date. Here, we demonstrate the preparation of polyquinolines via an AA/BB-type aza-Diels–Alder polymerization reaction. This approach requires only commercial starting materials and two straightforward synthetic steps to furnish the desired products in high yield. Overall, our modular and general route may afford new opportunities for the rational design and preparation of quinoline-based materials.

Polyquinolines have been studied since the early 1970s due to their favorable chemical, optical, electrical, and mechanical properties. However, surprisingly few synthetic strategies have been developed for the preparation of these polymers. Herein, we demonstrate the application of the aza-Diels–Alder (Povarov) reaction for the synthesis of soluble polyquinolines from a bifunctional monomer. Our approach furnishes polyquinolines with a unique architecture and connectivity in only two synthetic steps from inexpensive, commercially available reagents. The reported strategy may therefore represent a welcome addition to the polymer chemist’s toolkit by providing ready access to a diverse library of polyquinoline-type materials.

Graphene nanoribbons (GNRs) are promising candidate materials for the next generation of nanoscale electronics. Described herein is the synthesis of 2,4,6-substituted benzoquinolines, which constitute building blocks for nitrogen-doped GNRs. The presented facile and modular aza-Diels–Alder chemistry accommodates the installation of diverse functionalities at the crowded benzoquinolines’ 2 positions. Given the general utility of the benzoquinoline motif, these findings hold relevance not only for carbon-based electronics but also for a range of chemical disciplines.

The axial conformer of several 4-substituted cyclohexanone hydrazone salts was found to predominate in solution. Changes in the charge of the molecule and the polarity of the solvent led to changes in the conformational preference of each molecule that were consistent with electrostatic stabilization of the axial conformer. (1)H NMR spectroscopic analysis was utilized to determine the structure of cyclohexanone-derived substrates by comparison to conformationally restricted trans-decalone derivatives and computational models. X-ray crystallography demonstrated that the axial configuration of a pendant benzyloxy group is the preferred conformation of an iminium ion in the solid state. The structure of a neutral hydrazone was also determined to favor the axial configuration for a pendant benzyloxy group in the solid state.

Graphene nanoribbons (GNRs) represent promising materials for the next generation of nanoscale electronics. However, despite substantial progress towards the bottom-up synthesis of chemically and structurally well-defined all-carbon GNRs, strategies for the preparation of their nitrogen-doped analogs remain at a nascent stage. This scarce literature precedent is surprising given the established use of substitutional doping for tuning the properties of electronic materials. Herein, we report the synthesis of a previously unknown class of polybenzoquinoline-based materials, which have potential as GNR precursors. Our scalable and facile approach employs few synthetic steps, inexpensive commercial starting materials, and straightforward reaction conditions. Moreover, due to the importance of quinoline derivatives for a variety of applications, the reported findings may hold implications across a diverse range of chemical and physical disciplines.