Synthesis and reactivity of photochromic 2H-chromenes based on 3-carboxylated c...

• Author(s): Cerqueira, N. M. F. S. A. ; Rodrigues, Lígia M. ; Campos, Ana M. F. Oliveira ; Carvalho, Luís H. Melo de ; Coelho, Paulo J. ; Dubest, Roger ; Aubard, Jean ; Samat, André ; Guglielmetti, Robert J.
• Date: 2003
• Persistent ID: http://hdl.handle.net/1822/1024
• Origin: RepositóriUM - Universidade do Minho
• Subject(s): Photochromic; Carboxylated coumarins; 2H-chromenes; Benzopyrans
• Document Type: Article
• Language: English

Description

New photochromic 2H-chromenes including a 3-carboxylated coumarin nucleus were synthesised from hydroxycoumarins, and, in one case, the corrresponding trimethoxysilylcarboxamide was prepared. The photochromic behaviour was studied under flash photolysis conditions. The introduction of electron-withdrawing substituents in this position of the coumarin nucleus led to a global and significant bathochromic shift in the spectra of the open forms and to an interesting intensification in the colorability.