Concentration depending fluorescence of 8-(di-(2-picolyl)) aminoBODIPY in solution

Abstract

[EN] An 8-dipicolylBODIPY derivative has been prepared and its photophysical properties evaluated under different conditions. Two different structures, hemicyanine and cyanine, are observed (depending on the solvent or the solution concentration). The hemicyanine form is not emissive whereas the cyanine form is fluorescent. This behavior is related with the planarity degree of the BODIPY core. The X-ray structure of the compound is reported and it shows that in solid state the hemicyanine form is present. The hemicyanine form seems to be stabilized by aggregation and is the main compound in concentrated solutions whereas the cyanine form is present in diluted solutions that are photochemically transformed into a new compound 3. Both species cyanine and hemicyanine, are able to complex Zn2+ being the complex with the cyanine form of higher stability. The presence of the cation precludes any ulterior transformation from the cyanine form. (C) 2014 Elsevier Ltd. All rights reserved.