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Pandey S.S.,Kyushu Institute of Technology | Watanabe R.,Kyushu Institute of Technology | Fujikawa N.,Kyushu Institute of Technology | Shivashimpi G.M.,Kyushu Institute of Technology | And 3 more authors.
Tetrahedron | Year: 2013

Aiming toward the far-red to near infra-red (NIR) photon harvesting, three new unsymmetrical squaraine dyes bearing direct ring carboxy functionalized indole as an anchoring moiety with varying donor groups with extended π-conjugation have been successfully synthesized and utilized for dye sensitized solar cell fabrication. Under simulated solar irradiation, dye SQ-8 gave a photoconversion efficiency of 3.3% mainly harvesting photons in the far-red region between 500 and 700 nm. By extending the π-conjugation of the donor moieties in the novel unsymmetrical squaraine dyes, it was possible to extend the light absorption from far-red to NIR wavelength region. In spite of good light absorption up to 900 nm and energetic matching, dye SQ-16 was found to exhibit the decreased photon harvesting, which was explained by the enhanced dye aggregation along with its difficulty in facile electron injection as indicated from electronic absorption spectroscopic and DFT calculation results, respectively. © 2013 Elsevier Ltd. All rights reserved. Source


Yoon J.,Keimyung University | Adachi K.,Marine Biotechnology Institute | Adachi K.,Nippon Steel and Sumikin Chemical Co. | Kasai H.,Kitasato University
Antonie van Leeuwenhoek, International Journal of General and Molecular Microbiology | Year: 2014

A Gram-negative, strictly aerobic, pale-yellow pigmented, rod-shaped bacterium designated A4O-5T was isolated from a red coloured marine alga (Chondrus ocellatus Holmes). Phylogenetic analyses based on the 16S rRNA gene sequence indicated that the new strain was affiliated with the family Flavobacteriaceae and shared approximately 90 % sequence similarity with Leptobacterium flavescens YM3-0301T and Gangjinia marincola GJ16 T. The strain could be differentiated phenotypically from the related members of the family Flavobacteriaceae. The major fatty acids of strain A4O-5T were identified as iso-C15:0, iso-C17:0 3-OH and summed feature 3 (C16:1 ω7c and/or C16:1 ω6c). A complex polar lipid profile was present consisting of phosphatidylethanolamine, an unidentified phospholipid, three unidentified amino lipids and an unidentified lipid. The DNA G+C content of the strain was determined to be 41.9 mol% and the major respiratory quinone was identified as menaquinone 6 (MK-6). From the distinct phylogenetic position and combination of genotypic and phenotypic characteristics, the strain is considered to represent a novel genus in the family Flavobacteriaceae, for which the name Citreitalea marina gen. nov., sp. nov. is proposed. The type strain of C. marina is A4O-5T (=KCTC 32483T=NBRC 109918T). © 2014 Springer International Publishing. Source


Yoon J.,Keimyung University | Adachi K.,Marine Biotechnology Institute | Adachi K.,Nippon Steel and Sumikin Chemical Co. | Kasai H.,Kitasato University
Journal of General and Applied Microbiology | Year: 2014

A Gram-negative, strictly aerobic, reddish-pink-pigmented, non-motile, rod-shaped strain designated A6F-52T was isolated from a lake sediment sample. Preliminary analysis based on the 16S rRNA gene sequence revealed that the novel isolate could be affiliated with the family Catalimonadaceae of the phylum Bacteroidetes and that it showed highest sequence similarity (97.2%) to Catalinimonas alkaloidigena CNU-914T. The level of DNA-DNA relatedness between strains A6F-52T and Catalinimonas alkaloidigena CNU-914T was less than 70%, which is accepted as the phylogenetic definition of a species. The DNA G+C content of strain A6F-52T was 44.4 mol%; MK-7 was the major menaquinone; and the presence of iso-C15: 0, C16: 1 ω5C and iso-C17: 0 3-OH as the major cellular fatty acids supported the identification of the novel isolate as a member of the genus Catalinimonas. A complex polar lipid profile was present consisting of phosphatidylethanolamine, an unidentified phospholipid, and an unidentified lipid. From the distinct phylogenetic position and combination of genotypic and phenotypic characteristics, the strain is considered to represent a novel species for which the name Catalinimonas niigatensis sp. nov. is proposed. The type strain of Catalinimonas niigatensis is A6F-52T (= KCTC 32474T = NBRC 109829T). © 2014 Applied Microbiology, Molecular and Cellular Biosciences Research Foundation. Source


Hirata S.,Kyushu University | Sakai Y.,Kyushu University | Sakai Y.,Dyden Corporation | Masui K.,Kyushu University | And 18 more authors.
Nature Materials | Year: 2015

Organic compounds that exhibit highly efficient, stable blue emission are required to realize inexpensive organic light-emitting diodes for future displays and lighting applications. Here, we define the design rules for increasing the electroluminescence efficiency of blue-emitting organic molecules that exhibit thermally activated delayed fluorescence. We show that a large delocalization of the highest occupied molecular orbital and lowest unoccupied molecular orbital in these charge-transfer compounds enhances the rate of radiative decay considerably by inducing a large oscillator strength even when there is a small overlap between the two wavefunctions. A compound based on our design principles exhibited a high rate of fluorescence decay and efficient up-conversion of triplet excitons into singlet excited states, leading to both photoluminescence and internal electroluminescence quantum yields of nearly 100%. © 2015 Macmillan Publishers Limited. All rights reserved. Source


Li J.,Kyushu University | Zhang Q.,Kyushu University | Nomura H.,Kyushu University | Miyazaki H.,Kyushu University | And 2 more authors.
Applied Physics Letters | Year: 2014

Intense nπ∗ fluorescence from a nitrogen-rich heterocyclic compound, 2,5,8-tris(4-fluoro-3-methylphenyl)-1,3,4,6,7,9,9b-heptaazaphenalene (HAP-3MF), is demonstrated. The overlap-forbidden nature of the nπ∗ transition and the higher energy of the 3ππ∗ state than the 3nπ∗ one lead to a small energy difference between the lowest singlet (S1) and triplet (T1) excited states of HAP-3MF. Green-emitting HAP-3MF has a moderate photoluminescence quantum yield of 0.26 in both toluene and doped film. However, an organic light-emitting diode containing HAP-3MF achieved a high external quantum efficiency of 6.0%, indicating that HAP-3MF harvests singlet excitons through a thermally activated T1 → S1 pathway in the electroluminescent process. © 2014 AIP Publishing LLC. Source

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