Synthesis of di-phenyl-conjugated azadipyrromethene and its BF2 complex.

Azadipyrromethenes are the bridged nitrogen analogs of dipyrromethenes. Since they were considered as potential photosensitizers for photodynamic therapy, the synthesis of tetraarylazadipyrromethene-BF2 complexes has attracted the interest of several research groups. However, X-ray crystallog. anal. of the parent chromophore, 3,3’,5,5’-tetraphenyl-azadipyrromethene-BF2 complex, showed that none of the four Ph groups were effectively conjugated with the core plane of the azadipyrromethene-BF2 complex. This finding drew our attention to explore the synthesis of Π-conjugated azadipyrromethene-BF2 complexes, and the visible max. absorption of BF2 complex of indol-2-yl-isoindol-1-ylidene-amine (3) has reached to 528 nm. [on SciFinder(R)]