ChemInform Abstract: Insertion-Coupling-Cycloisomerization Domino Synthesis and Cation-Induced Halochromic Fluorescence of 2,4-Diarylpyrano[2,3-b]indoles.
ABSTRACT 2,4-Diarylpyrano[2,3-b]indoles are formed via a Pd-Cu-catalyzed insertion-coupling-cycloisomerization domino reaction in moderate yields. Although the tricyclic systems are nonfluorescent in solution, protonation, quaternation, or complexation with metal ions induces intense green luminescence. Most strikingly, selective halochromic fluorescence of zinc and magnesium over calcium ions classify the title compounds as metal-selective luminescence sensors.
- SourceAvailable from: Heiner Detert
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- "In addition to nitriles, fluorination, and other electron-withdrawing groups on a benzene ring, electron-deficient heterocycles like oxadiazole, triazine, or pyridazine are also suitable as acceptors in πconjugated oligomers. The interaction of these compounds with the environment can result in significant spectroscopic changes, useful for sensing purposes  . A few alkoxysubstituted distyrylpyrazines had been prepared    and investigated for optoelectronic devices, as emitting materials for lasing purposes  , and also as twophoton absorbing dyes . "
ABSTRACT: A series of linear and angular distyrylpyrazines and lateral donor groups has been prepared by aldol condensation between dimethylpyrazines and the appropriate aromatic aldehyde. The optical absorption and emission properties of these systems were studied in different solvents and media. The materials display a strong solvatochromism of the emission that is reflected by large red shifts of their fluorescence emission maxima on increasing the solvent polarity. This behaviour suggests a highly polar emitting state, which is characteristic of compounds that undergo an internal charge transfer upon excitation. Upon protonation, the UV-vis spectra are altered, and the fluorescence intensity of the neutral compound vanishes. These molecules can be used as colorimetric and luminescence polarity and pH sensors.04/2011; 2011:589012. DOI:10.5402/2011/589012
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ABSTRACT: The importance of palladium-catalyzed cross coupling reactions in contemporary organic synthesis is undisputed and underlined by the Nobel Prize for Chemistry in 2010. In addition to the highly efficient cross coupling reactions for single CC bond construction, palladium-catalyzed cascade processes involving multiple bond formations have emerged in recent years as valuable tools for the rapid synthesis of complex molecular scaffolds. This review presents an overview of the most relevant developments in this field, with a focus on the generation of diverse poly- and heterocyclic scaffolds. The generally well understood reactivity of palladium has allowed the discovery of many intriguing novel cascade processes, and the creativity of the synthetic community will undoubtedly lead to many more discoveries in the future.Advanced Synthesis & Catalysis 04/2011; 353(6):809 - 841. DOI:10.1002/adsc.201000979 · 5.66 Impact Factor
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ABSTRACT: Novel bichromophoric spirocyclic indolones have been synthesized by an insertion-coupling-isomerization-Diels-Alder domino reaction. The emission colors are strongly affected by the substituents: N-Boc leads to intense blue fluorescence, N-dansyl causes turquoise emission, whereas a 1-anthryl substituent on the butadiene results in yellow luminescence. The latter behavior is rationalized by TDDFT computations as a result of significant geometrical changes.Organic & Biomolecular Chemistry 07/2011; 9(18):6196-9. DOI:10.1039/c1ob05703k · 3.56 Impact Factor