Synthesis and Structural Characterization of a Novel Symmetrical 2,10-Bis-Styryl-1-Benzopyrylium Dye

A novel symmetrical 2,10-bis-styryl-1-benzopyrylium dye was synthesized through two steps: In the first reaction an aldol condensation between 2,4,6-trihydroxybenzaldehyde and 3,4-dihydroxy­methylstyrylketone gave 5,7,3′,4′-tetrahydroxy-2-styryl-1-benzopyrylium; and in the second step this latter reacted with the same ketone by a cycloaddition reaction yielding the symmetrical 2,10-bis(3,4-di­hydroxystyryl)-pyrano-7-hydroxy-1-benzopyrylium. The dye was fully characterized by LC-DAD/ESI-MS and NMR 1D and 2D techniques, and a formation pathway was proposed. The novel dye obtained revealed extended π-conjugation (λmax 556 nm) and catechol groups in its composition, which is very important for applications as a photosensitizer for dye-sensitive solar cells (DSSCs).