Yoshikazu Umemoto

Electronegative oligothiophenes based on difluorodioxocyclopentene-annelated thiophenes: synthesis, properties, and n-type FET performances.

A series of oligothiophenes containing difluorodioxocyclopentene-annelated thiophene units was synthesized, and their electronic properties and structures were investigated by spectroscopic and electrochemical measurements and X-ray analyses. The oligothiophenes having the terminal difluorodioxocyclopentene annelations showed n-type semiconducting behavior on FET devices, and the quaterthiophene revealed field-effect electron mobility as high as 1.3 x 10(-2) cm2 V(-1) s(-1).

Electronegative Oligothiophenes Fully Annelated with Hexafluorocyclopentene: Synthesis, Properties, and Intrinsic Electron Mobility

Synthesis of hexafluorocyclopenta[c]thiophene-repeated oligothiophenes up to 6-mer has been accomplished. The photophysical and electrochemical properties of these oligomers unambiguously exemplify marked electronegative character without disrupting the effective conjugation. The combination of time-resolved microwave conductivity and transient optical spectroscopy measurements of the 6-mer revealed the intrinsic electron mobility to be as high as 2.0 x 10(-1) cm(2) V(-1) s(-1).

Redox-active tubular frameworks with TTF: self-assemblies by complementary hydrogen-bonds and π-stacks of TTF-phenyluracil

Tubular frameworks of a tetrathiafulvalene (TTF) based electron-donor with a N1-phenyluracil moiety were constructed by strong self-assembling abilities. The uracil moiety formed the reversed Watson–Crick type hydrogen-bond pair. The TTF moiety exhibited C–H⋯X hydrogen-bonds, S⋯S interactions, and uniform π-stack. The phenyl group formed a herring-bone array by the edge-to-face interaction. These multiple intermolecular interactions established channels of ca. 4 × 8 A. The cavities were filled with crystalline solvent molecules (tetrahydrofuran and pyridine), which were fixed on the framework by the C–H⋯X hydrogen-bonds.

Modulation of charge-transfer complexes assisted by complementary hydrogen bonds of nucleobases: TCNQ complexes of a uracil-substituted EDO-TTF

A hydrogen bond functionalized ethylenedioxytetrathiafulvalene (EDO-TTF) derivative having an n-butyluracil moiety was synthesized. In the crystal structure, the Watson–Crick-type complementary hydrogen bonds of the uracil moiety formed a pair of donor molecules, which further aggregated by S⋯S interactions and π-stacks of the TTF moiety to construct a two-dimensional sheet. In the charge-transfer complex formation with tetracyanoquinodimethane, the crystallization conditions modulated the subtle balance between Watson–Crick and reverse Watson–Crick types of complementary hydrogen-bonded pairs, controlling stoichiometry, ionicity and molecular packing of the complexes. A highly conducting mixed valence complex with the Watson–Crick-type hydrogen bonds was yielded by the quick evaporation of reaction solvent, and a low-conducting neutral complex forming reverse Watson–Crick-type hydrogen bonds was obtained by the slow vapor diffusion method.