(Dibenzoylmethanato)boron difluoride derivatives containing triphenylamine moieties were synthesized as a new type of electron-donor/π-acceptor system. These new compounds exhibited long-wavelength absorptions in the UV/Vis spectra, and reversible oxidation and reduction waves in cyclic voltammetry experiments. Their amphoteric redox properties are based on their resonance hybrid forms, in which a positive charge is delocalized on the triphenylamine moieties and a negative charge is localized on the boron atoms. Molecular orbital (MO) calculations indicate that their HOMO and LUMO energies vary with the number of phenylene rings connected to the difluoroboron-chelating ring. This is useful for optimizing the HOMO and LUMO levels to an iodine redox (I(-)/I3(-)) potential and a titanium dioxide conduction band, respectively. Dye-sensitized solar cells fabricated by using these compounds as dye sensitizers exhibited solar-to-electric power conversion efficiencies of 2.7-4.4 % under AM 1.5 solar light.

Looking at crystal structures makes us feel as if we are in a museum. Molecules are self‐assembled to form beautiful crystal structures. Herein, bis(dioxaborin) compounds containing 2,2′‐bithiophene derivatives were synthesized as n‐type semiconductors for organic field‐effect transistors (OFETs). An OFET fabricated using one of these compounds having a layer‐by‐layer crystal structure exhibited n‐type semiconductor behavior with a low threshold voltage. This OFET performance was studied by theoretical calculations based on the crystal structure. More information can be found in the Full Paper by Katsuhiko Ono et al.

Bis(dioxaborin) compounds containing π‐conjugated systems have been studied as n‐type semiconductors for organic field‐effect transistors (OFETs). In this study, with the aim of investigating the effect of the extension of the π‐conjugation on the n‐type semiconducting properties and stability of bis(dioxaborin) compounds, we synthesized new compounds containing 2,2′‐bithiophene derivatives extended with an olefin or an acetylene spacer. The absorption maxima of the compounds containing olefin spacers were greatly red‐shifted compared with those of the original compound without a π‐spacer. The newly synthesized compounds exhibited high electron affinity, and the olefin spacers effectively reduced the on‐site Coulomb repulsion in the two‐electron reduction of the compounds. An OFET fabricated using one of these compounds having a layer‐by‐layer crystal structure exhibited n‐type semiconductor behavior with a low threshold voltage, most likely due to the small on‐site Coulomb repulsion. The electron‐transporting properties were investigated by theoretical calculations based on the Marcus theory.