π-Extended Pyrrole-Fused Heteropine: Synthesis, Properties, and Application in Organic Field-Effect Transistors.

Sulfur-embedded polycyclic aromatic compounds have been used as building blocks for numerous organic semiconductors over the past few decades. While the success is based on thiophene-containing compounds, aromatic compounds that contain thiepine, a sulfur-containing seven-membered-ring arene, has been less well investigated. Here we report the synthesis and properties of π-extended pyrrole-fused heteropine compounds such as thiepine and oxepine. A π-extended pyrrole-fused thiepine exhibited a "pitched π-stacking" structure in the crystal, and exhibited a high charge carrier mobility of up to 1.0 cm2 V-1 s-1 in single-crystal field-effect transistors.

Fully conjugated azacorannulene dimer as large diaza[80]fullerene fragment.

A fully conjugated azacorannulene dimer with a large π-surface (76π system) was successfully synthesized from a fully conjugated bifunctional polycyclic aromatic azomethine ylide. This molecule represents an example of diaza[80]fullerene (C78N2) fragment molecule bearing two internal nitrogen atoms. X-ray crystallography analysis shows its boat-shaped structure with two terminal azacorannulenes bent in the same direction. The molecular shape leads to unique selective association with a dumbbell-shaped C60 dimer (C120) over C60 through shape recognition. Owing to its large π-surface and a narrow HOMO-LUMO gap, the azacorannulene dimer exhibits red fluorescence with a quantum yield of up to 31%. The utilization of the fully conjugated bifunctional azomethine ylide is a powerful method for the bottom-up synthesis of large multiazafullerene fragments, providing a step towards the selective total synthesis of multiazafullerenes.

Biocompatible Choline Iodide Catalysts for Green Living Radical Polymerization of Functional Polymers.

Herein, nontoxic and metabolizable choline iodide analogues, including choline iodide, acetylcholine iodide, and butyrylcholine iodide, were successfully utilized as novel catalysts for "green" living radical polymerization (LRP). Through the combination of several green solvents (ethyl lactate, ethanol, and water), this green LRP process yielded low-polydispersity hydrophobic, hydrophilic, zwitterionic, and water-soluble biocompatible polymethacrylates and polyacrylates with high monomer conversions. Well-defined hydrophobic-hydrophilic and hydrophilic-hydrophilic block copolymers were also synthesized. The accessibility to a range of polymer designs is an attractive feature of this polymerization. The use of nontoxic choline iodide catalysts as well as green polymerization conditions can contribute to sustainable polymer chemistry.