The synthesis of structurally well-defined, monodisperse carbon nanotube (CNT) sidewall segments poses a challenge in materials science. The synthesis of polyphenylene cylinders that comprise typical benzene connectivity to resemble precursors of [9,9] and [15,15] CNTs is now reported, and the products were characterized by X-ray crystallography. To investigate the oxidative cyclodehydrogenation of ring-strained molecules as a final step towards a bottom-up synthesis of CNT sidewall segments, phenylene-extended cyclic p-hexaphenylbenzene trimers ([3]CHPB) were prepared, and NMR studies revealed a strain-induced 1,2-phenyl shift. It was further shown that an increase in ring size leads to selectively dehydrogenated macrocycles. Larger homologues are envisioned to give smooth condensation reactions toward graphenic sidewalls and should be used in the future as seeds for CNT formation.

This review summarizes the past present, and future developments of isocyanate chemistry for polyurethane coatings and adhesives. Over the past 60 years, this field was driven by numerous breakthrough innovations that helped improve coating applications with respect to customer's needs—cementing the features of this outstanding material class. We provide a short introduction on the early beginnings of industrial isocyanate chemistry and then a detailed overview on the building blocks as well as the rich chemistry of the isocyanate group. The synthesis of various derivatives is described. An outlook on the latest developments—new building blocks and new chemistries—is given in the field of isocyanate coating and adhesive chemistry. © 2018 Society of Chemical Industry

Unsubstituted and structurally well-defined poly(para-phenylene) (PPP) has been long-desired as an organic semiconductor prototype of conjugated polymers. To date, several attempts to synthesize unsubstituted, pristine, high-molecular-weight PPP have failed. Here we solved this synthetic problem by a versatile precursor route. Suzuki polymerization of kinked disubstituted 1,4-dimethoxycyclohexadienylene monomers yielded a well-soluble, nonaromatic precursor polymer. Its solubility allowed processing by spin-coating into nanometer-thick films. Subsequent additive-free thermal treatment induced aromatization and led to exclusively para-connected, highly fluorescent PPP with a length of about 75 phenylene units.

The longitudinal extension of cycloparaphenylenes (CPP) towards ultrashort carbon nanotubes (CNTs) is essential for the solution based bottom-up synthesis of CNTs. Herein, the longitudinal extension of the CPP skeleton by the introduction of hexaphenylbenzene units towards polyarylated [n]CPPs is described. Further, the applicability of the Scholl reaction to selectively form graphenic sidewalls is demonstrated. The ring size and substitution patterns of the polyarylated [n]CPPs were varied to overcome strain-induced side reactions during the oxidative cyclodehydrogenation and cyclic para-hexa-peri-hexabenzocoronene trimers ([3]CHBCs) were selectively obtained. This concept is envisioned as an access to ultrashort carbon nanotubes subject to the condition that further benzene rings with the right connectivity will be inserted.