Boradipyrromethenecyanines

A series of meso-polymethine-substituted BODIPY compounds have been synthesized by the reaction of mesomethyl-3,5-diphenylboradipyrromethene with a number of hemicyanine derivatives. The dyes obtained exhibit intense long-wavelength absorption, but weak fluorescence. Upon protonation of the dyes the long-wavelength band disappears and the intensity of the short-wavelength band increases significantly. It has been shown that the properties of the dyes obtained, which we call boradipyrromethenecyanines, are closely related to those of merocyanine dyes rather than those of boron dipyrromethenes. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)