ChemInform Abstract: Methylenepyran Based Dipolar and Quadrupolar Dyes: Synthesis, Electrochemical and Photochemical Properties.

Abstract

Abstract This paper presents the synthesis of a series of push–pull and quadrupolar π-conjugated structures incorporating pro-aromatic methylenepyran electron-donor groups and various electron-attracting groups. Some of the methylenepyran derivatives were oxidized by I 2 to give, after reduction by Na 2 S 2 O 3 , bismethylenepyran compounds via successive steps. The electrochemical redox properties of methylenepyrans 5 – 9 and extended bismethylenepyrans 10 , 14 , and 15 determined by cyclic voltammetry indicate the formation of redox bistable systems with high bi-stability. Oxidation of the dimers obtained from 5 to 9 was also described. All compounds are colored and slightly fluorescent (except some bismethylenepyran derivatives). Some compound second-order nonlinear optical properties were investigated, and large positive values of μβ were obtained. A positive dimer effect was also observed for bispyran derivatives.