Synthesis and Photophysical Properties of a Binuclear Symmetrical Analog of BODIPY with Unconjugated Fluorophores

4,4′-(1,4-Phenylenebis(oxy))diphthalonitrile has been synthesized via the interaction of 4-nitrophthalonitrile with hydroquinone. The treatment of the obtained compound with sodium ethylate in ethanol, followed by acid hydrolysis of the resulting alkoxyimino derivative, has led to the formation of 5,5′-(1,4-phenylenebis(oxy))bis(isoindoline-1,3-dione). The reaction of the latter with quinaldine in the presence of zinc oxide has afforded 6,6′-(1,4-phenylenebis(oxy))bis(3-(quinolin-2-ylmethylene)isoindolin-1-one), the treatment of which with BF₃·Et₂O in the presence of triethylamine in toluene has yielded a new binuclear symmetrical analog of BODIPY with unconjugated chromophores: (3Z,3′Z)-6,6′-(1,4-phenylenebis(oxy))bis(2-(difluoroboryl)-3-(quinolin-2-ylmethylene)isoindolin-1-one). The complex has exhibited the Stokes shift of 8 nm and high relative quantum yield of fluorescence (0.53). The results of DFT and TDDFT simulations are presented to support the experimental data.