Organic letters

Synthesis of novel quinaldine-based squaraine dyes: effect of substituents and role of electronic factors

K Jyothish, KT Arun, D Ramaiah

Index: Jyothish, Kuthanapillil; Arun, Kalliat T.; Ramaiah, Danaboyina Organic Letters, 2004 , vol. 6, # 22 p. 3965 - 3968

Full Text: HTML

Citation Number: 49

Abstract

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 ...