Fluorescence Properties of 2-Substituted 6-, 7- or 8-Methoxyquinoline-4-carboxylic Acid Derivatives

Tomohiko YOSHIDA; Youichi MORIYAMA; Saburo NAKANO

doi:10.1248/cpb.40.1322

Tomohiko YOSHIDA, Youichi MORIYAMA, Saburo NAKANO

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Keywords: 2-substituted 6-methoxyquinoline-4-carboxylic acid, 6-methoxy-2-methylsulfonylquinoline-4-carboxylic acid, ethyl 6-methoxy-2-methylsulfonylquinoline-4-carboxylate, fluorescence property, quantum yield

JOURNAL FREE ACCESS

1992 Volume 40 Issue 5 Pages 1322-1324

DOI https://doi.org/10.1248/cpb.40.1322

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Abstract

2-Substituted 6-, 7- or 8-methoxyquinoline-4-carboxylic acid derivatives were synthesized. The fluorescence quantum yield (Φ) of these compounds increased in the order, 2-thioxo-, 2-methylthio-, 2-methylsulfinyl-, 2-methylsulfonyl derivatives of 6-methoxyquinoline-4-carboxylic acid. Ethyl 6-methoxy-2-methylsulfonylquinoline-4-carboxylate (Φ_CH₃CN=0.74 or Φ_EtOH=0.69) showed a much higher fluorescence quantum yield than those (Φ_CH₃CN=0.19 or Φ_EtOH=0.19 and Φ_CH₃CN=0.16 or Φ_EtOH=0.05) of the 7- and 8-methoxy derivatives in both acetonitrile and ethanol.

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