Synthesis of Novel Quinaldine-Based Squaraine Dyes:  Effect of Substituents and Role of Electronic Factors

Condensation of squaric acid with quinaldinium salts containing electron-donating substituents gave only the semisquaraines. However, with salts possessing electronegative and electron-withdrawing groups, the squaraine dyes were isolated in quantitative yields. The semisquaraines formed undergo cond...

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Veröffentlicht in:Organic letters 2004-10, Vol.6 (22), p.3965-3968
Hauptverfasser: Jyothish, Kuthanapillil, Arun, Kalliat T, Ramaiah, Danaboyina
Format: Artikel
Sprache:eng
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Zusammenfassung:Condensation of squaric acid with quinaldinium salts containing electron-donating substituents gave only the semisquaraines. However, with salts possessing electronegative and electron-withdrawing groups, the squaraine dyes were isolated in quantitative yields. The semisquaraines formed undergo condensation with highly nucleophilic salts yielding the unsymmetrical squaraine dyes. These results demonstrate the role of electronic factors and provide valuable information for the design of efficient squaraine-based sensitizers that can have potential applications in photodynamic therapy.
ISSN:1523-7060
1523-7052
DOI:10.1021/ol048411y