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2020-1

Bridged Stilbenes: AIEgens Designed via a Simple Strategy to Control the Non-radiative Decay Pathway
R. Iwai, S. Suzuk, S. Sasaki, K. Igawa, T. Suenobu, K. Morokuma, G. Konishi*
Angew. Chem. Int. Ed., 59, 10566–10573 (2020)
DOI: 10.1002/anie.202000943
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京都大学 研究成果
東工大 研究成果
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Abstract: To broaden the application of aggregation‐induced emission (AIE) luminogens (AIEgens), the design of novel small‐molecular dyes that exhibit high fluorescence quantum yield ( Φ fl ) in the solid state is required. Considering that the mechanism of AIE can be rationalized based on steric avoidance of non‐radiative decay pathways, a series of bridged stilbenes was designed, and their non‐radiative decay pathways were investigated theoretically. Bridged stilbenes with short alkyl chains exhibited a strong fluorescence emission in solution and in the solid state, while bridged stilbenes with long alkyl chains exhibited AIE. Based on this theoretical prediction, we developed the bridged stilbenes BPST[7] and DPB[7] , which demonstrate excellent AIE behavior.


# by konishi_lab | 2020-04-23 20:03 | 2020 (3)

2019-2

Synthesis of fluorescent polycarbonates with highly twisted N,N-bis(dialkylamino)anthracene AIE luminogens in the main chain
Amir S. Sairi, K. Kuwahara, S. Sasaki, S. Suzuki, K. Igawa, M. Tokita, S. Ando, K. Morokuma, T. Suenobu, G. Konishi*
RSC Adv., 9, 21733–21740 (2019)
DOI: 10.1039/c9ra03701b
Link
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Abstract: A synthetic route to embed aggregation-induced-emission-(AIE)-active luminophores in polycarbonates (PCs) in various ratios is reported. The AIE-active monomer is based on the structure of 9,10-bis(piperidyl)anthracene. The obtained PCs display good film-forming properties, similar to those observed in poly(bisphenol A carbonate) (Ba-PC). The fluorescence quantum yield (Ф) of the PC with 5 mol% AIE-active monomer was 0.04 in solution and 0.53 in solid state. Moreover, this PC is also miscible with commercially available Ba-PC at any blending ratios. A combined analysis by scanning electron microscopy and differential scanning calorimetry did not indicate any clear phase separation. These results thus suggests that even engineering plastics like polycarbonates can be functionalized with AIE luminogens without adverse effects on its physical properties.

# by konishi_lab | 2019-07-13 00:10 | 2019 (3)

2019-1

Synthesis and Luminescence Properties of Diamine Monomers and Polyamides with Highly Twisted N,N-Bis(dialkylamino)arene AIE Luminogens
Amir S. Sairi, G. Konishi*
Asian J. Org. Chem., 8, 404–410 (2019)
DOI: 10.1002/ajoc.201900056
Link

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Abstract: We report the synthesis of aggregation-induced emission (AIE)-active polyamides through the polycondensation of diamine monomers 1,4-bis(N,N-dialkylamino)-2,3-dimethylnaphthalene or 9,10-bis(N,N-dialkylamino)anthracene chromophores with α,ω-bis(chlorocarbonyl)alkane. The obtained anthracene polyamide was soluble in common organic solvents, such as dichloromethane and methanol, and demonstrated good film-forming properties. The quantum yields in the solid state of the naphthalene and anthracene polyamides were both 0.26, and the quantum yields in solution of the naphthalene and anthracene polyamides were 0.23 and 0.04, respectively. The results of this study will provide valuable information regarding the application of AIE-active polymers in organic light-emitting diodes (OLED) and in polymer research.

# by konishi_lab | 2019-02-07 13:46 | 2019 (3)

2018-3

次世代の光学材料を指向した高複屈折性液晶の開発
Development of High-Birefringence Liquid Crystals for Future Optical Materials
荒川優樹、小西玄一
Y. Arakawa, G. Konishi
有機合成化学協会誌, in press (2018).
J. Syn. Org. Chem. Jpn., in press (2018).
10月号に掲載予定 
DOI: @
Abstract: High-birefringence liquid crystal materials are used in a wide variety of optical devices such as OLEDs and photo storage devices; they are likely to find more applications with increasing research in this area. The design concept is an essential aspect of high-birefringence liquid crystals. We investigated the structure-optical property relationship (liquid crystallinity, refractive index and birefringence) of rod-like mesogens from the viewpoint of physical organic chemistry. We first investigated how the acetylene bond affects nematic transition behavior and refractive index parameters of the conjugated oligoyne or polyyne compounds with two terminal aromatic rings. We synthesized novel, highly birefringent nematic liquid crystal materials: 1,6-diphenyl-1,3,5-hexatriyne derivatives with various alkoxy chains. The derivatives exhibit stable enantiotropic nematic phases when longer alkoxy carbon chains are used. In the case of the msogen with hexyloxy groups, m = 6, high birefringence value of 0.45 at 550 nm and 140 °C. We revealed that a higher number of acetylene units (from 1 to –3), i.e., extended conjugation, led to wider temperature range nematic phases and higher birefringence. The increment in Δn per acetylene unit was estimated to be 0.14. We then studied the use of heteroatoms with high atomic refraction. Sulfur-containing rod-like materials usually have high birefringence values but do not exhibit enantiotropic mesophases because they tend to crystallize or show mesophase instability. We incorporated carboxylic acid end groups into thioether-containing diphenyl-acetylene-based compounds, our hypothesis being that the acid groups would impart mesophase stability through hydrogen-bond driven dimerization. These compounds exhibited highly correlated long-range mesophases and high birefringence compared with their alkyl and alkoxy analogues. We also developed a new and simple process to prepare phenolic-hydroxyl-group substituted diphenyl-acetylene and diphenyl-diyne derivatives. Using these molecules, we prepared transparent and colorless high-birefringence polymer films. Our studies show that this review could be a guide for the design of high-birefringence liquid crystal materials.

# by konishi_lab | 2018-08-04 02:08 | 2018(3)

2018-2

トリハロメタンを選択的に検出する光分解性ゲルの開発
Development of a Photo-degradable Gel that Selectively Detects Trihalomethane
小西玄一
Gen-ichi KONISHI
光学8月号掲載
Japanese Journal of Optics, in press
Since light allows for spatiotemporal control of gel degradation, photodegradable gels are applied not only to polymer recycle, but also to analytical research. Conventionally additional functions of photocleavable crosslinkers such as strong fluorescence and detection properties have been equipped separately with additional functional groups and chromophores, resulting in complicated structures. To tackle the problem, this research developed a bis(piperidyl)naphthalene analogue which integrated photocleavable degradation, strong fluorescence and molecular recognition properties into its simple structure. Our presentation will elucidate design strategy for the novel type of the photocleavable crosslinker for detection of environmental pollutants.

# by konishi_lab | 2018-06-05 09:48 | 2018(3)