Daisuke Sakamaki

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Charge carrier mobility is an essential parameter providing control over the performance of semiconductor devices fabricated using a variety of organic molecular materials. Recent design strategies toward molecular materials have been directed at the substitution of amorphous silicon-based semiconductors; accordingly, numerous measurement techniques have(More)
Curved π-conjugated molecules have attracted considerable interest because of the unique properties originating from their curved π surface. However, the synthesis of such distorted molecules requires harsh conditions, which hamper easy access to heteroatom-containing curved π systems. Here we report the synthesis of a π-extended azacorannulene with(More)
Three kinds of para-phenylenediamine (PDA) derivatives bearing nitronyl nitroxide (NN) groups were prepared and characterized on the basis of the electrochemical, electron spin resonance (ESR) spectroscopic, absorption spectroscopic, and magnetic susceptibility measurements. It was clarified that the oxidation potential of the central PDA unit is strongly(More)
In bulk materials, positional isomers not only help in understanding how slight difference in molecular structure alters the crystal packing and optical properties, but also play a key role in developing new type of materials for functional applications. A detailed study on the photophysical properties of fluorene-HBT positional isomers in solution and in(More)
A series of 6,13-diamino-substituted pentacenes 1 a-d has been prepared and characterized as a new class of pentacene derivatives with strong donor ability and enhanced solubility in common organic solvents. The spectroelectrochemical and DFT studies revealed that the two-electron oxidation process was accompanied by the substantial structural change into a(More)
Although several types of belt-shaped compounds with novel structures have been reported over the past 30 years, they are currently receiving increasing attention in conjunction with the synthesis of the shortest possible segments of singlewalled carbon nanotubes. Nanoscaled beltlike molecules are considered to be “cycles of cycles”, and thus they have(More)
Radical cations of bis(triarylamine)s, 3 and 4, in which the triarylamine redox centers are bridged by an ortho-phenylene and ortho-carborane cluster, respectively, have been prepared to elucidate the difference in intramolecular charge/spin-transfer (ICT/IST) pathway owing to the two different bridging units affording similar geometrical arrangements(More)
Novel double N-hetero[5]helicenes that are composed of two nitrogen-substituted heteropentacenes are synthesized by tandem oxidative CN couplings via the cruciform heteropentacene dimers. The developed method is very facile and enables the synthesis of a double helicene in only two steps from commercially available naphthalene derivatives. These double(More)
Protein nanowires exhibiting specific biological activities hold promise for interacting with living cells and controlling and predicting biological responses such as apoptosis, endocytosis and cell adhesion. Here we report the result of the interaction of a single high-energy charged particle with protein molecules, giving size-controlled protein nanowires(More)