- Synthesis, crystal structures and spectroscopic characterizations of two difluoroboradiaza-s-indacene dyes
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Two new 8-(4-dimethylaminophenyl) substituted boron-dipyrromethene (BDP) dyes: 1,2,6,7-tetraethyl-4,4-difluoro-3,5-dimethyl-8-(4-dimethylaminophenyl)-4-bora-3a,4a-diaza-s-indacene (5) and 4,4-difluoro-1,2,3,5,6,7-hexamethyl-8-(4-dimethylaminophenyl)-4-bora-3a,4a-diaza-s-indacene (6) have been synthesized and their crystal structures are determined by X-ray diffraction analysis. The torsion angles of 8-phenyl ring and the indacene plane are 79.61° for 5 and 87.56° for 6, respectively. The absorption and steady-state fluorescence properties in different solvents have been investigated. The fluorescence quantum yields of the two dyes are lower in more polar solvents, which can be ascribed to the intramolecular charge transfer from the aniline to the BDP unit. Protonation of the aniline moiety at low pH in MeOH-H2O (1:1 v/v) solution causes a large fluorescence enhancement. The pKa values calculated from the pH dependent fluorescence emission spectra are 3.14 for 5 and 3.09 for 6, respectively. They are suitable as pH probes excitable with visible light.
- Yu, Yan-Hong,Shen, Zhen,Xu, Hai-Yun,Wang, Yan-Wei,Okujima, Tetsuo,Ono, Noboru,Li, Yi-Zhi,You, Xiao-Zeng
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- One-pot synthesis of asymmetric annulated bis(pyrrole)s
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Condensation of activated functionalized pyrroles with acetone results in asymmetric bis(pyrrole)s, formed via ring annulation. The methodology is somewhat general and can be applied to a variety of ketones, as well as to a range of pyrrolic substrates that do not bear electron-withdrawing groups directly adjacent to the pyrrole ring.
- Smithen, Deborah A.,Cameron, T. Stanley,Thompson, Alison
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supporting information; experimental part
p. 5846 - 5849
(2012/01/13)
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- Nonionic superbase-promoted synthesis of oxazoles and pyrroles: Facile synthesis of porphyrins and α-C-acyl amino acid esters
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The reaction of acyl chlorides or acid anhydrides with isocyanoacetates in the presence of the superior strong nonionic base P(MeNCH2CH2)3N (1) gave oxazoles in 98-99% yield. Treatment of the oxazoles with HCl-MeOH gave α-
- Tang,Verkade
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p. 7793 - 7802
(2007/10/02)
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