학술논문
Two-Step Synthesis of Blue Luminescent (Pyrrol-3-yl)-1 H-(aza)indazoles Based on a Three-Component Coupling-Cyclocondensation Sequence.
Document Type
Article
Source
Subject
*PYRROLES
*CHEMICAL synthesis
*INDAZOLES
*CONDENSATION
*DENSITY functional theory
*STOKES equations
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Language
ISSN
1434-193X
Abstract
(Pyrrol-3-yl)-1 H-(aza)indazoles can be efficiently prepared by a two-step process that consists of a consecutive three-component coupling-cyclocondensation synthesis to give ortho-halo-3-acylpyrrol-3-yl-substituted (hetero)arenes followed by a cyclization-condensation-SNAr sequence. Almost all derivatives display an intense blue emission upon excitation in the near UV with enormous Stokes shifts (6500-8300 cm-1) and considerable high fluorescence quantum yields ( Φf = 0.28-0.46). Electronic transitions can be plausibly rationalized by TD-DFT computations performed on DFT-optimized geometries. Reversible protonation leads to static fluorescence quenching in narrow pH-ranges, which qualifies the title compounds as favorable ON/OFF fluorescence switching systems. [ABSTRACT FROM AUTHOR]