Conformational isomerism in squaraines: saturation transfer NMR studies on hydroxy squaraines

PM Kazmaier, GK Hamer…

Index: Kazmaier, Peter M.; Hamer, Gordon K.; Burt, Richard A. Canadian Journal of Chemistry, 1990 , vol. 68, # 4 p. 530 - 536

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Citation Number: 30

Abstract

The proton and 13C NMR of azulene and dialkylaminohydroxyphenyl squaraines have been investigated. The four-membered ring carbon resonances occur in the 180-190 ppm range and are attributed to the cyclobutenediylium character of this structure. Some charge delocalization from the central ring to the pendent aromatic substituents was also observed, indicative of a substituent effect of the squaraine moiety on aminoaromatic systems ...