A controlled blue-shift in meso-nitrogen aryl fused DIPY and BODIPY skeletons

Abstract

meso-Nitrogen substituted dipyrromethenes (DIPYs) and their boron(III) complexes (BODIPYs) were obtained by the method of nucleophilic aromatic substitution. The following intramolecular fusion with the formation of a 3H-[2,3-c]quinoline skeleton extends delocalisation, but shifts the absorption and emission hypsochromically. A further blue shift has been observed for a deprotonated form of the fused system. A nitrogen atom introduced into the system can be treated as a switching factor that controls the delocalisation significantly influencing the emission by shifting between the available amine and imine tautomeric forms.