Electron deficient cyclopentadienolate in the synthesis of chromophores with mono- and poly-cyclic hydrazonocyclopentadiene acceptor moieties

Abstract

The use of stabilized exocyclic cyclopentadienone enolate, containing three ester groups and a dicyanomethylene fragment, allowed the replacement of unstable cyclopentadienones in the synthesis of arylhydrazonopentadiene chromophores. The presence of reaction centers in the resulting chromophores allowed three additional series of compounds to be obtained. Two series of compounds lost coplanarity in conjugated systems and exhibited reduced extinction coefficients, however, the absorption maxima were red-shifted. In one of the series of chromophores the formation of an imide cycle led to the record red-shift of the absorption maxima by up to 160 nm with only slightly reduced extinction coefficients.