Search

Your search keyword '"Ohshita, Joji"' showing total 1,205 results
Start Over Author "Ohshita, Joji"
1,205 results on '"Ohshita, Joji"'

21. Phosphorescence Properties of Boron/Bismuth Hybrid Conjugated Materials.

Author

Adachi, Yohei, Terao, Shota, Kanematsu, Yusuke, and Ohshita, Joji

Abstract

By introducing main–group elements such as boron and bismuth to π‐conjugated systems, it is possible to modify the optical properties of π‐conjugated materials through orbital interactions between the orbital on the elements and π/π*‐orbitals, and the heavy atom effect. Moreover, bismuth, which is the heaviest stable element, induces a significant heavy atom effect, making organobismuth compounds promising for applications as phosphorescent materials. In this study, we synthesized new room–temperature phosphorescent materials by incorporating bismuth into thiophene units. The phosphorescence properties of these materials, such as emission lifetime and wavelength, could be further controlled by combining tricoordinate boron with the thienylbismuth structures. The synthesized bismuth‐ and boron–containing thiophene compounds exhibited phosphorescence at room temperature in both solution and solid states. Furthermore, the introduction of boron raised the energy of the triplet state in the π‐conjugated system, resulting in a blue shift of the phosphorescence wavelength. The analysis of photoluminescence properties and TD‐DFT calculations revealed that the introduction of bismuth enhances phosphorescence properties, whereas the introduction of boron further promotes intersystem crossing. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

22. Preparation of Polysilsesquioxane-Based CO 2 Separation Membranes with Thermally Degradable Succinic Anhydride and Urea Units.

Author

Horata, Katsuhiro, Yoshio, Tsubasa, Miyazaki, Ryuto, Adachi, Yohei, Kanezashi, Masakoto, Tsuru, Toshinori, and Ohshita, Joji

Subjects
SUCCINIC anhydride, MEMBRANE separation, CARBON dioxide, UREA, HIGH temperatures, ETHANES
Abstract

New polysilsesquioxane (PSQ)-based CO2 separation membranes with succinic anhydride and monoalkylurea units as thermally degradable CO2-philic units were prepared by the copolymerization of a 1:1 mixture of [3-(triethoxysilyl)propyl]succinic anhydride (TESPS) or [3-(triethoxysilyl)propyl]urea (TESPU) and bis(triethoxysilyl)ethane (BTESE). The succinic anhydride and monoalkylurea units underwent thermal degradation to form ester and dialkylurea units, respectively, with the liberation of small molecules (e.g., CO2 and NH3) under N2 atmosphere. The effects of thermal degradation on the performance of the obtained membranes were investigated. The TESPS-BTESE- and TESPU-BTESE-based membranes calcined at 250 °C and 200 °C exhibited good CO2/N2 permselectivities of 20.2 and 14.4, respectively, with CO2 permeances of 7.7 × 10−8 and 7.9 × 10−8 mol m−2·s−1·Pa−1, respectively. When the membranes were further calcined at elevated temperatures of 350 °C and 300 °C, respectively, to promote the thermal degradation of the organic units, the CO2 permeances increased to 1.3 × 10−7 and 1.2 × 10−6 mol m−2·s−1·Pa−1 (3.9 × 102 and 3.6 × 103 GPU), although the CO2/N2 permselectivities decreased to 19.5 and 8.4, respectively. These data indicate that the controlled thermal degradation of the organic units provides a new methodology for possible tuning of the CO2 separation performance of PSQ membranes. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results