Research

TOPICS

Dye-sensitized solar cell

Y. Adachi , T. Nabeya , T. Nomura , K. Kondo , K. Kawakami , Y. Ooyama and J. Ohshita; Direct comparison of dithienosilole and dithienogermole as π-conjugated linkers in photosensitizers for dye-sensitized solar cells; Dalton Trans., 2019, 48, 16671 - 16678.

Dye-sensitized solar cells (DSSCs) based on DTG-containing dyes exhibited superior performance compared to those based on DTS-containing dyes, presumably due to their different aggregation states.









Heat-shielding material

S. Tsukada, Y. Nakanishi, H. Kai, T. Ishimoto, K. Okada, Y. Adachi, J. Ohshita; NIR-shielding films based on PEDOT-PSS/polysiloxane and polysilsesquioxane hybrid; J. Appl. Polym. Sci., 2019, 136, 48367-48376.

Nearinfrared (NIR)‐shielding polysilsesquioxane films were synthesized via a sol–gel reaction of TEOS in the presence of poly(3,4‐ethylenedioxythiophene)‐poly(4‐styrene sulfonate) (PEDOT‐PSS), which are expected as transparent heat-shielding materials.







Heat- and chlorine-resistant water separation membrane

D. Zhang, J. Ohshita; Preparation of robust RO membrane for water desalination by interfacial copolymerization of bis[(triethoxysilyl)propyl]amine and bis(triethoxysilyl)ethane ; Polym. J., 2019, 51(11), 1231-1234.

Interfacial sol-gel copolymerization of bis[(triethoxysilyl)propyl]amine and bis(triethoxysilyl)ethane successfully provided a desalination membrane with high thermal and chlorine resistance.









OLED material

J. Ohshita, T. Kai, Y. Adachi, K. Yamaji, M. Nakamura, S. Watase, S. Mori,N. Matsuyama; Synthesis of non-planar bipyridyls bridged by disilane and disiloxane and their phosphorescent copper complexes; Appl. Organomet. Chem., 2019, e5306.

Disilane‐ and disiloxane‐bridged bipyridyls (DSBPy and DSOBPy) were prepared as new emissive materials and their phosphorescent properties and applications to OLEDs were explored.









D-A material

J. Ohshita, M. Sugino, Y. Ooyama, Y. Adachi; Synthesis of Pyridinothienogermoles as Unsymmetrically Condensed Germoles; Organometallics, 2019, 38(7), 1606-1613.

Pyridinothienogermoles (PyTGs) were prepared as new D-A compounds. The Lewis basicity of the pyridine ring made it possible to use these DPyG derivatives as sensing materials. For example, complex formation of the PyTG pyridine unit with (C6F5)3B changed the optical properties.









Solid-state phosphorescent material

J. Ohshita, K. Yamaji, Y. Ooyama, Y. Adachi, M. Nakamura, S. Watase; Synthesis, Properties, and Complex Formation of Antimony- and Bismuth-Bridged Bipyridyls; Organometallics, 2019, 38(7), 1516-1523.

Antimony- and bismuth-bridged bipyridyls (DPySb and DPyBi) were prepared for the first time. Their copper complexes were also prepared, which produced red phosphorescence in the solid state at room temperature.









Intramolecular energy transfer

Y. Adachi, T. Nomura, J. Ohshita; Intramolecular Energy Transfer in Dithienogermole Derivatives;Chem.Eur. J., 2019, 25, 4974-4983.

New DTG derivatives with bulky aryl substituents showed efficient photoenergy transfer between the DTG core and the substituents, indicating the potential application of the new DTG system as optical functional materials.









Interfacial sol-gel polymerization for water separation membrane

F.-T. Zheng, K. Yamamoto, M. Kanezashi, T. Gunji, T. Tsuru, J. Ohshita; Preparation of Hybrid Organosilica Reverse Osmosis Membranes by Interfacial Polymerization of Bis[(trialkoxysilyl)propyl]amine, Chem. Lett., 2018, 47, 1210-1212.

Interfacial sol-gel polymerization of bis[(triethoxysilyl)propyl]amine readily provided a desalination membrane.









Photosensitizer

J. Ohshita, Y. Hayashi, Y. Adachi, T. Enoki, K. Yamaji, Y. Ooyama; Optical and Photosensitizing Properties of Spiro(dipyridinogermole)(dithienogermole)s with Eletron-Donating Amino and Electron-Withdrawing Pyridinothiadiazole Substituents; ChemSelect, 2018, 3, 8604-8609.

Three spiro(dipyridinogermole)(dithienogermole) derivatives with conjugated substituents on the dithienogermole system were synthesized. The sDPyGs were examined as photosensitizers for singlet oxygen (1O2) generation.









Water separation membrane

K. Yamamoto, H. Muragishi, T. Mizumo, T. Gunji, M. Kazezashi, T. Tsuru, J. Ohshita; Diethylenedioxane-bridged microporous organosilica membrane for gas and water separation; Sep. Pur. Tech., 2018, 207, 370-376.

High performance desalination RO membranes were obtained by sol-gel reactions of a dioxane-containing triethoxysilane precursor.









Hybrid conjugated polymer

Y. Adachi, Y. Ooyama, Y. Ren, X. Yin, F. Jäkle, J. Ohshita; Hybrid conjugated polymers with alternating dithienosilole or dithienogermole and tricoordinate boron units; Polym. Chem., 2018, 9, 291-299.

Hybrid conjugated polymers composed of alternately arranged Si/Ge-containing DTS/STG units and B-based BDTTD/FBDT units were prepared. Optical properties of the polymers can be finely controlled by the combination of the units.











Water separation membrane

F.-T. Zheng, K. Yamamoto, M. Kanezashi, T. Tsuru, J. Ohshita; Preparation of bridged silica RO membranes from copolymerization of bis(triethoxysilyl)ethene/(hydroxymethyl)triethoxysilane. Effects of ethenylene-bridge enhancing water permeability; J. Membr. Sci., 2018, 546, 173-178.

Potential applications of membranes prepared from copolymerization of HMTES and BTESE to efficient water separation were demonstrated.










Water separation membrane

K. Yamamoto, M. Kanezashi, T. Tsuru, J. Ohshita; Preparation of bridged polysilsesquioxane-based membranes containing 1,2,3-triazole moieties for water desalination; Polym J., 2017, 49, 401-406.

Membranes derived from hydrolysis/condensation of a triazoloe-containing bridged alkoxysilane were examined as water separation membrane indicating their good performance.










Organic semiconductor

J. Ohshita, Y. Adachi, R. Sagisaka, M. Nakashima, Y. Ooyama, Y. Kunugi; Synthesis of dithienogermole-containing Polythiophenes; Syn. Met., 2017, 227, 87-92.

A series of DTG- and DTS-containing conjugated polymers were prepared and their optical properties and transistor activities were investigated.










Nitrobenzene sensor

M. Nakamura, K. Shigeoka, Y. Adachi, Y. Ooyama, S. Watase, J. Ohshita; Preparation of Dithienogermole-containing Polysilsesquioxane Films for Sensing Nitroaromatics; Chem. Lett., 2017, 46, 438-441.

DTG-containing porous photoluminescent silsesquioxane films were prepared. They underwent PL quenching on contact with a nitrobenzene vapor, thereby potentially useful as sensing materials of nitroaromatic compounds.










Sensitizing dye

Y. Adachi, Y. Ooyama, N. Shibayama, J. Ohshita; Dithienogermole-containing D-π-A-π-A Photosensitizers for Dye-sensitized Solar Cells; Chem. Lett., 2017, 46, 310-312.

New DTG-based sensitizing dyes for dye-sensitized solar cells were prepared.










Water separation membrane

K. Yamamoto, S. Koge, T. Gunji, M. Kanezashi, T. Tsuru, J. Ohshita; Preparation of POSS-derived robust RO membranes for water desalination; Desalination, 2017, 404, 322-327.

Porous membranes with high performance water separation properties were prepared by hydrolysis/condensation of a POSS (polyhedral oligomeric silsesquioxane)-cored alkoxysilane. They exhibited high stability towards high temperature operation and exposure to chlorine, being useful as robust membranes.










Phosphorescent materials

K. Murakami, Y. Ooyama, S. Watase, K. Matsukawa, S. Omagari, T. Nakanishi, Y. Hasegawa, K. Inumaru, J. Ohshita; Synthesis of Dipyridinogermole-Copper Complex as Soluble Phosphorescent Material; Chem. Lett.; 2016, 45, 502-504. DOI: 10.1246/cl.160036

The reaction of diphenyldipyridinogermole with Cu2I2(PPh3)3 afforded a complex with high thermal stability. Sufficient solubility of the complex permitted the fabrication of a complex-doped PMMA self-standing phosphorescent film.









Photoelectron transfer

K. Murakami, Y. Ooyama, H. Higashimura, J. Ohshita; Synthesis, Properties, and Polymerization of Spiro[(dipyridinogermole)(dithienogermole)]; Organometallics, 2016, 35, 20-26.DOI: 10.1021/acs.organomet.5b00817

Spiro-compounds with bipyridyl and bithiophene bridged by a germanium atom were prepared. They showed interesting photo-electron and –energy transfer, depending on the substituents (R).









Water separation membrane

Yamamoto, K; Ohshita, J; Mizumo, T; Kanezashi, M; Tsuru, T; Preparation of hydroxyl group containing bridged organosilica membranes for water desalination ; SEPARATION AND PURIFICATION TECHNOLOGY, 2015, 156, 396-402. doi: 10.1016/j.seppur.2015.10.028

Silica membranes were prepared from HMTES(hydroxymathyltriethoxysilane)and examined for water-separation. Soaking the membranes in water resulted in the partial hydrolysis of Si-O-C bonds to generate Si-OH and C-OH units, improving the water permeability without suppressing the separation selectivity.









Sensing of nitrobenzene

Ohshita, J.; Nakamura, M.; Ooyama, Y.; Preparation and Reactions of Dichlorodithienogermoles; Organometallics, 2015, 34, 5609-5614. doi: 10.1021/acs.organomet.

Dichlorodithienogermoles were prepared for the first time. These dichlorides readily underwent nucleophilic substitution, leading to dihitenogermoles with a variety of substituents on the germanium atom. Of those, a dithienogermole-containing cyclotetragermoxane showed excellent sensing proeprties towards nitrobenzene vapor in the solid state.










Organic thin film solar cell

Nakashima, M.; Otsura, T.; Naito, H.; Ohshita, J.; Synthesis of new D-A polymers containing disilanobithiophene donor and application to bulk heterojunction polymer solar cells; Polym. J., 2015, 47, 733-738.doi:10.1038/pj.2015.

New D-A conjugated polymers were prepared and the photovoltaic applications of the polymers were examined.








Bridged silica separation membrane

Mizumo, T.; Muragishi, H.; Yamamoto, K.; Ohshita, J.; Kanezashi, M.; Tsuru, T.; Preparation and separation properties of oxalylurea-bridged silica membranes; Appl. Organomet. Chem., 2015, 29, 433-438. doi: 10.1002/aoc.3311

Oxalylurea-containing bridged silica membranes were prepared and their applications to water and CO2 separation were explored.









Electrochromic Material 

Murakami, K.; Ohshita, J.; Inagi, S.; Tomita, I.; Synthesis, and Optical and Electrochemical Properties of Germanium-Bridged Viologen; Electrochemistry, 2015, 83, 605-608.

A Ge-bridged methylviologen derivative (GMV2+) was synthesized by dimethylation of dipyridinogermole and the stable electrochromic properties were explored.










Phosphorescent Organoantimony Compounds

J. Ohshita, T. Tsuchida, K. Murakami, Y. Ooyama, T. Nakanishi, Y. Hasegawa, N. Kobayashi, H. Higashimura; Distibylation of Acetylenes with Ph2Sb-SbPh2: Synthesis, Crystal Structures and Phosphorescence Properties of Bis(diphenylstibyl)ethenes, Z. Naturforschung B, 2014, 69, 1181-1187.

Bisstibylethenes were prepared by insertion reactions of acetylenes to Sb-Sb bonds. The resulting compounds were found to show phosphorescence in the solid state.









Dye-Sensitized Solar Cell Materials

J. Ohshita, Y. Adachi, D. Tanaka, M. Nakashima, Y. Ooyama; Synthesis of D-A Polymers with a Disilanobithiophene donor and a Pyridine or Pyrazine Ccceptor and Their Applications to Dye-Sensitized Solar Cells, RSC ADV., 2015, 5, 36673-36679.

Conjugated D-A-type polymers with disilanobithiophene as the donor were synthesized. It was found that the polymers reacted with titanium oxide surface forming Ti-O-Si bonds to attach the polymers on the surface. The polymer-attached titanium oxide was applicable as active electrodes in dye-sensitized solar cells.









Luminescent Silsequioxanes

J. Ohshita, M. Nakamura, K. Yamamoto, S. Watase, K. Matsukawa; Synthesis of Dithienogermole-Containing Oligo- and Polysilsesquioxanes as Luminescent Materials; Dalton Trans., 2015, 44, 8214-8222.

Oligo- and polysilsesquioxanes with dithienogermole as the chromophore were prepared as new PL and EL materials.







Sol-Gel reaction Mechanism of Bridged Alkoxysilanes

K. Yamamoto, J. Ohshita, T. Mizumo, T. Tsuru; Polymerization Behavior and Gel Properties of Ethane, Ethylene and Acetylene-Bridged Polysilsesquioxanes; J. Sol-Gel Tech. Sci., 2014, 71, 24-30.

Effects of the structure of organic bridge on the silica structure derived from sol-gel reactions of bridged alkoxysilanes were studied, which provided important information about the structural control of the bridged silica.










Organic Thin Film Solar Cell Materials

F.-B. Zhang, J. Ohshita, M. Miyazaki, D. Tanaka, Y. Morihara; Effects of Substituents and Molecular Weight on the Optical, Thermal, and Photovoltaic Properties of Alternating Dithienogermole-Dithienylbenzothiadiazole Polymers; Polym. J., in press.

DEffects of substituents and molecular weight of DTG-containing polymers on the performance as OPV host materials were explored.











Dithienostannole

Tanaka, D.; Ohshita, J.; Ooyama, Y.; Kobayashi, N.; Higashimura, H.; Nakanishi, T.; Hasegawa, Y. Organometallics, 2013, 32, 4136-4141.

Tin-bridged bithiophene (dithienostannole) was prepared for the first time, which exhibits crystallization-enhanced emission and the photoluminescence quantum yield of the crystals was determined to be higher by about 20 times than that in the amorphous and solution phase.










New Photovoltaic Material

Ohshita, J.; Nakashima, M.; Tanaka, D.; Morihara, Y.; Fueno, H.; Tanaka, K. Polym. Chem., 2014, 5, 346 – 349.

A new polymer with disilanobithiophene units was prepared, which was applied to polymer solar cell to provide a high power conversion efficiency of 6.38%.








Si- and Ge-Bridged Bipyridyls

Ohshita, J.; Murakami, K.; Tanaka, D.; Ooyama, Y.; Mizumo, T.; Kobayashi, N.; Higashimura, H.; Nakanishi, T.; Hasegawa, Y. Organometallics, in press.

Silicon- and germanium-bridged bipyridyls were synthesized and their solid-state phosphorescence was explored. They are anticipated as new π-conjugated systems with electron-deficient and emissive properties.










New D-A-type Organosilicon polymers

Ohshita, J.; Kajihara, T.; Tanaka, D.; Ooyama, Y. J. Organomet. Chem., 2013, 749, 255-260.

New D-A (donor-acceptor)-type organosilicon polymers that showed red-shifted absorption were prepared and their potential applications as chromic and DSSC materials were explored.










Polydithienogermole

Ohshita, J.; Miyazaki, M.; Tanaka, D.; Morihara, Y.; Fujita, Y.; Kunugi, Y. Polym. Chem. 2013, 4, 3116-3122.

Germanium-bridged polythiophenes (polydithienogermoles) were prepared for the first time and their potential applications as active materials for organic transistor and solar cell were explored.








New Organic Thin Film Solar Cell Materials with the Use of Group 14 Elements

Ohshita, J.; Miyazaki, M.; Zhang, Fei-Bao.; Tanaka, D.; Morihara, Y. Polym. J. 2013, 45, 979-984.

New dithienometallole-pyridinothiadiazole polymers were prepared. They were applied to organic thin film solar cells, whose maximal power conversion efficiency reached 3.36%.








New Element- blocks with Solid State Fluorescence Properties

Ohshita, J.; Tominaga, Y.; Tanaka, D.; Ooyama, Y.; Mizumo, T.; Kobayashi, N.; Higashimura, H., Dalton Trans. 2013, 42, 3646-3652.

Silicon-bridged bithiophenes with efficient solid state fluorescence properties were prepared. It was found that those with boryl substituent(s) responded to fluoride anion, being potentially applicable to fluoride-sensing.








Microphase Separation of Siloxane-oligothiophene Polymer Films

Lu, Z.; Ohshita, J.; Tanaka, D.; Mizumo, T.; Fujita, Y.; Kunugi, Y. J. Organomet. Chem. 2013, 731, 73-77.

New siloxane-oligothiophene polymers were prepared. They showed microphase separated structures in the films, providing a new methodology to control the polymer interface and hierarchical structures.









Solubilization of Carbon Nanotube

Lu, Z.; Ohshita, J.; Tanaka, D.; Mizumo, T.; Fujita, Y.; Kunugi, Y. Composite Interfaces 2012, 19, 573-581

New oligosiloxane-polymers were prepared as the first silicon-based materials that solubilize carbon nanotube by the hybrid formation.