Improved Synthesis of 5-(R-group)-10, 15, 20-tris(4-methylphenyl)porphyrins as Starting Compounds for the Preparation of Potential Sensitizer in Solar Cells

This paper presented a simple and effective method for the synthesis of unsymmetrical meso-phenyl-substituted porphyrins, which could be applied to link blocks for dye-sensitized solar cells of different structures. In order to overcome the main disadvantages associated with the need of highly toxic oxidant and unavoidable side reactions in the reported synthetic methods of unsymmetrical meso-phenyl-substituted porphyrins, an improved Macdonald-type 2+2 condensation based on the mixed solvents of dipyrromethanes and aldehydes were adopted to synthesize a series of 5-(R-group)-10, 15 and20-tris (4-methylphenyl) porphyrins, and all the structures were characterized by melting point analysis, electronic absorption spectroscopy and 1H NMR spectroscopy. As a result, the high yield (13-17%) of A3B-type porphyrins as potential sensitizers in solar cells could be obtained by this new synthetic method.