Yuuki Sako

Facile and reversible synthesis of an acidic water-soluble poly(amidoamine) fullerodendrimer

Water-soluble fullerodendrimer was obtained by the use of a Diels–Alder reaction of C60 with a newly designed anthryl dendron under an extremely mild condition in 70% yield, which is more than five times as high as the yield described in our previous report.

A photo-responsive hydrogelator having gluconamides at its peripheral branches

A newly designed anthracene derivative having gluconamides at its peripheral branches formed a photo-responsive hydrogel. SEM observation of the xerogel showed a network structure consisting of fibrils. Upon photoirradiation (lambda >300 nm) of the hydrogel, regioselective photodimerization of the anthracene moiety occurred to give head-to-tail photodimers and the physical state changed from the gel to the sol.

Transport properties of field-effect transistor with Langmuir-Blodgett films of C60 dendrimer and estimation of impurity levels

Field-effect transistor (FET) device has been fabricated with Langmuir-Blodgett films of C60 dendrimer. The device showed n-channel normally off characteristics with the field-effect mobility of 2.7×10−3cm2V−1s−1 at 300K, whose value is twice as high as that (1.4×10−3cm2V−1s−1) for the FET with spin-coated films of C60 dendrimer. This originates from the formation of ordered π-conduction network of C60 moieties. From the temperature dependence of field-effect mobility, a structural phase transition has been observed at around 300K. Furthermore, the density of states for impurity levels was estimated in the Langmuir-Blodgett films.

Fabrication of field-effect transistor devices with fullerodendron by solution process

n-channel field-effect transistor (FET) devices have been fabricated with thin films of fullerodendron on SiO2∕Si, polyimide/Au/poly(ethylene terephthalate), and polyvinyl alcohol/Au/poly(ethylene terephthalate) substrates by using solution processes. The value of field-effect mobility μ of the fullerodendron FET reaches 1.7×10−3cm2V−1s−1 at 300K. The mobility gap and optical gap have been estimated to be 0.15 and 1.4eV, respectively. The channel conduction in the FET device follows thermally activated hopping-transport mechanism below 300K.

Synthesis and liquid crystallinity of fullerodendron having cyanobiphenyl groups at the terminals

Liquid-crystalline fullerodendron having cyanobiphenyl terminals was synthesized via Diels-Alder reaction of corresponding anthryl dendron and C60. The liquid-crystalline properties of the fullerodendron was investigated by polarized optical microscopy, differential scanning calorimetry, and X-ray diffraction. Interestingly, the fullerodendron give rise to thermotropic smectic B phase, in which the hexagonal packing arrangement of C60 moiety is observed.

SYNTHESIS OF FULLERODENDRON AND ITS PHOTOCATALITIC ACTIVITY

A newly designed fullerodendron was synthesized in good yield (84%) by the use of a Diels-Alder reaction of C60 with an anthryl dendron. Interestingly, the fullerodendron acts as a new catalyst that uses oxygen and light to generate singlet oxygen (1O2). The dendron facilitates various types of singlet oxygenation reactions including ene reaction, Diels-Alder reaction, and oxidation of phenol and sulfide.