JOURNAL OF PORPHYRINS AND PHTHALOCYANINES, vol.13, no.6, pp.702-711, 2009 (SCI-Expanded)
The synthesis and spectroscopic characterization of tetraimidazophthalocyanines are presented. This kind of molecules have not been intensively studied due to difficulty in (i) obtaining an easily obtainable synthon: a benzimidazole ring with a variety of substituent, and (ii) achieving the Rosenmund-Von Braun reaction with good yields. The synthesis of novel 2-substituted-5,6-dicyanobenzimidazoles (4a-e) achieved from 4,5-dibromo-N,N'-diacetylated-1,2-phenylene diamine (2a-e) or 2-substituted-5,6-dibromobenzimidazole (3a-e) were optimized. Depending on the starting compound, the reaction could be done according to a two-step pathway (cyclization followed by nitrilation) or a one-pot procedure using microwave irradiation. The target compounds, tetraimidazophthalocyanines (ImiPc(M)) (5a-e; 6a-d), were prepared. The effect of the four imidazoles introduced in the phthalocyanines core were compared and discussed.