title: Synthesis of 8-Aryl-O-methylcyanidins and Their Usage for Dye-Sensitized Solar Cell Devices.
abstract: Anthocyanins as natural pigments are colorful and environmentally compatible dyes for dye-sensitized solar cells (DSSCs). To increase the efficiency, we designed and synthesized unnaturalO-methylflavonols andO-methylcyanidins that possess an aryl group at the 8-position. We synthesizedper-O-methylquercetin from quercetin, then using selective demethylation prepared variousO-methylquercetins. Using the Suzuki-Miyaura coupling reaction, 8-arylation ofper-O-methylquercetin was achieved. Using a LiAlH₄ reduction or Clemmensen reduction, these flavonols were transformed to the corresponding cyanidin derivatives in satisfactory yields. Using these dyes, we fabricated DSSCs, and their efficiency was investigated. The efficiency oftetra-O-methylflavonol was 0.31%. However, the introduction of the 8-aryl residue increased the efficiency to 1.04%. In comparison to these flavonols,O-methylcyanidins exhibited a lower efficiency of 0.05% to 0.52%. The introduction of the 8-aryl group into the cyanidin derivatives did not result in a remarkable increase in the efficiency. These phenomena may be due to the poor fit of the HOMO-LUMO level of the dyes to the TiO₂ conduction band.
authors.affiliation: Graduate School of Information Science, Nagoya University, Chikusa, Nagoya 464-8601, Japan. kimura.yuki@i.mbox.nagoya-u.ac.jp.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Kimura
authors.affiliation: Chemical Instrumentation Facility, Research Center for Materials Science, Nagoya University, Chikusa, Nagoya 464-8602, Japan. oyama@cic.nagoya-u.ac.jp.
authors.forename: Kin-Ichi
authors.initials: KI
authors.lastname: Oyama
authors.affiliation: Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan. yasujiro@scl.kyoto-u.ac.jp.
authors.forename: Yasujiro
authors.initials: Y
authors.lastname: Murata
authors.affiliation: Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan. wakamiya@scl.kyoto-u.ac.jp.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Wakamiya
authors.affiliation: Graduate School of Information Science, Nagoya University, Chikusa, Nagoya 464-8601, Japan. yoshidak@is.nagoya-u.ac.jp.
authors.forename: Kumi
authors.initials: K
authors.lastname: Yoshida
mesh_terms: D000872:Anthocyanins / Q000138:chemical synthesis*; D004396:Coloring Agents / Q000737:chemistry*; D055668:Photochemical Processes; D011794:Quercetin / Q000031:analogs & derivatives / Q000138:chemical synthesis; D012993:Solar Energy
chemical_list: D000872:Anthocyanins; D004396:Coloring Agents; C012526:quercitrin; C017154:cyanidin; D011794:Quercetin
keywords: 8-aryl-O-methylcyanidin; 8-aryl-O-methylquercetin; O-methylcyanidin; O-methylquercetin; dye-sensitized solar cells