Guest-Host Interactions in Symmetrical Carboxy Heptamethine Cyanine Dyes-Titanium Dioxide Systems: Synthesis, Theoretical Calculations, Aggregation Properties, and Application in Dye-Sensitized Solar Cells

Scheme 1

Synthesis of heptamethine cyanines 12-14, where (i) CH₃COOH/reflux; (ii) CH₃CN/56°C, (iii) 1: DMF, 0-110°C, 2: aniline/EtOH, 0°C; (iv) dark, N₂, i-PrOH, CH₃COONa/reflux.