Fluorescent Organic Nanoparticles of Benzofuran−Naphthyridine Linked Molecules:  Formation and Fluorescence Enhancement in Aqueous Media

Sun, † Yeh-Yang; Liao, Jen-Hai; Fang, Jim‐Min; Chou, Pi‐Tai; Shen, § Ching-Hsing; Hsu, Chih-Wei; Chen, Li‐Chyong

doi:10.1021/ol061293p

Cited by 75 publications

(32 citation statements)

References 29 publications

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“…When the aryl halide has an ucleophilic substituent group (e.g.,O H) in the ortho position, cyclization to the corresponding heterocyclic compound occurs exclusively under Sonogashira reaction conditions. [30,31] Therefore, 1 was protected using acetic anhydride in al arge excess of pyridine to provide 2. After workup,t he crude reaction mixture was directly subjected to Sonogashira cross-couplingconditions (Pd II ,CuI, NEt 3 ,toluene), [31] with aromatic acetylenes to yield acetate-protected HBT 6.B yr emoving the acetate protecting group under alkaline condition (K 2 CO 3 ,M eOH/THF), the target 3'-substituted HBT derivatives 7 were obtained.…”

Section: Resultsmentioning

confidence: 99%

“…[30,31] Therefore, 1 was protected using acetic anhydride in al arge excess of pyridine to provide 2. After workup,t he crude reaction mixture was directly subjected to Sonogashira cross-couplingconditions (Pd II ,CuI, NEt 3 ,toluene), [31] with aromatic acetylenes to yield acetate-protected HBT 6.B yr emoving the acetate protecting group under alkaline condition (K 2 CO 3 ,M eOH/THF), the target 3'-substituted HBT derivatives 7 were obtained. Under the same Sonogashira cross-coupling conditions, 4'-bromo-substituted HBT derivative 3 reacted directlyw ith aromatic acetylenes to yield 4'-substituted HBT derivatives 8.…”

Section: Resultsmentioning

confidence: 99%

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Excited State Intramolecular Proton Transfer in Ethynyl‐Extended Regioisomers of 2‐(2′‐Hydroxyphenyl)benzothiazole: Effects of the Position and Electronic Nature of Substituent Groups

Wang

Niu

et al. 2016

Chemistry An Asian Journal

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Although the organic dyes based on excited state intramolecular proton transfer (ESIPT) mechanism have attracted significant attention, the structure-property relationship of ESIPT dyes needs to be further exploited. In this paper, three series of ethynyl-extended regioisomers of 2-(2'-hydroxyphenyl)benzothiazole (HBT), at the 3'-, 4'- and 6-positions, respectively, have been synthesized. Changes in the absorption and emission spectra were correlated with the position and electronic nature of the substituent groups. Although 4'- and 6-substituted HBT derivatives exhibited absorption bands at longer wavelengths, the keto-emission of 3'-substituted HBT derivatives was found at a substantially longer wavelength. The gradual red-shifted fluorescence emission was found for 3'-substituted HBT derivatives where the electron-donating nature of substituent group increased, which was opposite to what was observed for 4'- and 6-substituted HBT derivatives. The results derived from the theoretical calculations were in conformity with the experimental observations. Our study could potentially provide experimental and theoretical basis for designing novel ESIPT dyes that possess unique fluorescent properties.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Excited State Intramolecular Proton Transfer in Ethynyl‐Extended Regioisomers of 2‐(2′‐Hydroxyphenyl)benzothiazole: Effects of the Position and Electronic Nature of Substituent Groups

Wang

Niu

et al. 2016

Chemistry An Asian Journal

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“…Selective mono-iodination at the 3-position was achieved by using an excess of iodine monochloride on 5-methylsalicylaldehyde in acetic acid (59 % yield of isolated product). 3-Iodo-5-methyl- (23) [33] HBO 24 was first protected with an acetate group by reaction with acetic anhydride in dichloromethane with catalytic amounts of pyridine. The crude material was immediately subjected to Sonogashira conditions with p-tolylacetylene or pdibutylaminoacetylene as acetylene sources to yield acetate-protected HBOs 25 and 26 in 91 and 66 % yield, respectively.…”

Section: Synthesis Of the 3-substitutedmentioning

confidence: 99%

Synthesis of Luminescent Ethynyl‐Extended Regioisomers of Borate Complexes Based on 2‐(2′‐Hydroxyphenyl)benzoxazole

Massue

Frath

Retailleau

et al. 2013

Chemistry A European J

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A series of thirteen luminescent tetrahedral borate complexes based on the 2-(2'-hydroxyphenyl)benzoxazole (HBO) core is presented. Their synthesis includes the incorporation of an ethynyl fragment by Sonogashira cross-coupling reaction, with the goal of extending the conjugation and consequently redshifting their emission wavelength. Different regioisomers, substituted in the 3-, 4-, or 5-position of the phenolate side of the HBO core, were studied in order to compare their photophysical properties. The complexes were characterized by X-ray diffraction and NMR, UV/Vis, and emission spectroscopy in solution and in the solid state. In all cases, complexation to boron leads to a donor-acceptor character that impacts their photophysical properties. Complexes with a 3- or 5-substituted fragment display mild to pronounced internal charge transfer (ICT), a feature strengthened by the presence of p-dibutylaminophenylacetylene in the molecular structure, protonation of the nitrogen atom of which leads to a significant blueshift and an increase in quantum yield. On the contrary, when the ethynyl module is grafted on the 4-position, narrow, structured, symmetrical absorption/emission bands are observed. Moreover, the fact that protonation has little effect on the emission maximum wavelength reveals singlet excited-state decay. Solid-state emission properties reveal a redshift compared to solution, explained by tight packing of the π-conjugated systems and the high planarity of the dyes. Subsequent connection of these complexes to other photoactive subunits (BODIPY, Boranil) provides dyads in which efficient cascade energy transfer is observed.

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“…For instance, after formation of fluorescent organic nanoparticles (FONs1.) of ABAN (183, Scheme 7.62), the photophysical properties (such as the spectral features and intensity) are remarkably different from those at the molecular level (solution) and in bulk material [116].…”

Section: Uses Of Benzofuran In Materials Sciencementioning

confidence: 99%

Five‐Membered Heterocycles: Benzofuran and Related Systems

2011

Modern Heterocyclic Chemistry

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Fluorescent Organic Nanoparticles of Benzofuran−Naphthyridine Linked Molecules: Formation and Fluorescence Enhancement in Aqueous Media

Cited by 75 publications

References 29 publications

Excited State Intramolecular Proton Transfer in Ethynyl‐Extended Regioisomers of 2‐(2′‐Hydroxyphenyl)benzothiazole: Effects of the Position and Electronic Nature of Substituent Groups

Excited State Intramolecular Proton Transfer in Ethynyl‐Extended Regioisomers of 2‐(2′‐Hydroxyphenyl)benzothiazole: Effects of the Position and Electronic Nature of Substituent Groups

Synthesis of Luminescent Ethynyl‐Extended Regioisomers of Borate Complexes Based on 2‐(2′‐Hydroxyphenyl)benzoxazole

Five‐Membered Heterocycles: Benzofuran and Related Systems

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