Polymethine dyes derived from the boron difluoride complex of 3-acetyl-5,7-di(pyrrolidin-1-yl)-4-hydroxycoumarin

A boron difluoride complex of 3-acetyl-5,7-di(pyrrolidin-1-yl)-4-hydroxycoumarin was synthesized and converted into polymethine dyes which included an anionic, symmetric cyanine and several metocyanine compounds. The spectral luminescent behaviour of the dyes was studied. As the electron-withdrawing ability of the 2,2-difluoro-1,3,2-dioxaborine ring was significantly reduced by the two pyrrolidino groups on the latter nucleus, the newly synthesized dyes exhibited changes in spectral parameters and much increased resistance to hydrolysis. (C) 2008 Elsevier Ltd. All rights reserved.