ヒカリ オヨビ ネツ ヘンカンガタ ゼンクタイホウ オ モチイタ ヒカリ キノウセイ アセン ザイリョウ ノ ケンキュウ

博第1269号甲第1269号博士(理学)奈良先端科学技術大学院大

In situ preparation of highly fluorescent pyrene-dyes from non-luminous precursors upon photoirradiation

The non-luminous precursor, 2-(1-pyrenyl)-9,10-dihydro-9,10-ethanoanthracene-11,12-dione, was photochemically converted to highly-fluorescent 2-(1-pyrenyl)anthracene quantitatively in solution and in the PMMA film and the fluorescence quantum yield of the acene in benzonitrile was as high as 0.99

An Optically and Thermally Switchable Electronic Structure Based on an Anthracene-BODIPY Conjugate

An optically and thermally responsive boron dipyrromethene (BODIPY) dye, namely, meso-2-(9,10-dihydro-9,10-ethanoanthracene-11,12-dione) (DK)-linked, bicyclo[2.2.2]octadiene (BCOD)-fused BODIPY (BCOD-DK), was synthesized. The weakly luminous structure of BCOD-DK can be changed quantitatively to that of the strongly fluorescent BODIPY BCOD-Ant by optical excitation at the DK unit, which induces double decarbonylation of the DK unit to give an anthracene unit. The solvent effect on the fluorescence properties of BCOD-DK suggests that the dramatic change in fluorescence intensity is controlled by intramolecular electron transfer from the BODIPY moiety to the meso-DK substituent. BCOD-DK is converted to meso-DK benzene-fused BODIPY (Benzo-DK) by heating at 220°C with 64-70nm redshift of absorption and fluorescence peaks without changing the fluorescence quantum yield of ΦF=0.08 in dichloromethane. Benzo-DK can be converted to strongly fluorescent meso-anthracene benzene-fused BODIPY Benzo-Ant by optical excitation. Thus, BCOD-DK can show four different optical performances simply by irradiation and heating, and hence may be applicable for optical data storage and security data encryption

Synthesis, Structure, and Photochemistry of 5,14-Diketopentacene

5,14-α-Diketopentacene, a structural isomer of 6,13-α-diketopentacene, was prepared from pentacene in three steps. In addition to the typical n-π* absorption of the diketone moiety at around 468 nm and the anthracene-like absorption at 333, 349, and 367 nm, a broad absorption was observed at around 386 nm, which could be assigned to an intramolecular charge-transfer absorption from anthracene to the diketone moiety. 5,14-α-Diketopentacene could be converted into pentacene quantitatively by photoirradiation at 405 and 468 nm in toluene with quantum yields of 2.3 and 2.4 %, respectively, and these values are higher than the quantum yield of 1.4 % obtained for 6,13-α-diketopentacene irradiated at 468 nm. The quantum yields in acetonitrile were lowered to 0.33 and 0.28 % with irradiation at 405 and 468 nm. The crystal structure of 5,14-α-diketopentacene showed a CH-π interaction and π-π stacking between neighbouring anthracene and benzene moieties. The lower solubility of 5,14-α-diketopentacene compared with the 6,13-isomer could be explained by this crystal structure

Indolizino[5,6-b]quinoxaline Derivatives: Intramolecular Charge Transfer Characters and NIR Fluorescence

Indolizino[5,6-b]quinoxaline derivatives (1 a and 1 b) with a push-pull structure were prepared to show intramolecular charge-transfer properties. Compounds 1 a and 1 b are strongly fluorescent in aprotic solvents while symmetrical derivatives (2?a and 2?b) were non-fluorescent. The π-expanded α-α linked dimer (10) of indolizino[5,6-b]quinoxaline 1 b was serendipitously obtained to show NIR absorption over 800 nm and the fluorescence edge reached to 1400 nm

Synthesis and photoreactivity of α-diketone-type precursors of acenes and their use in organic-device fabrication

Acenes are highly promising p-type organic semiconductors, and have been the subject of intense studies. However, acenes are often low in solubility and stability, which poses major obstacles in the synthesis and processing of this class of compounds. In order to overcome the problem, a series of α-diketone-type acene precursors have been developed. These precursors are generally more soluble and stable than the corresponding acene compounds, and their quantitative conversion can be achieved simply by photoirradiation both in solution and in the solid state. Further, the irreversible photoinduced removal of the α-diketone unit can be used to alter the optoelectronic properties of fluorophores. This review overviews the synthesis and photochemical properties of α-diketone-type acene precursors, as well as their use as intermediates in preparation of large acenes or highly functionalized acene derivatives. Computational studies on the mechanism of α-diketone photolysis and the use of α-diketone derivatives in fabrication of organic devices are also summarized in this review