Design and synthesis of novel symmetrical heptamethine cyanine chromophores

In this study, near-infrared absorbing dyes, namely new rigidified heptamethine cyanines dyes, were synthesized by the reaction of bis-aldehyde-(1-formyl-3-hydroxymethylene)cyclohexene with 1,1,2-trimethylbenzindole derivatives. Two new rigidified heptamethine cyanine dyes were readily prepared by a novel semi-catalyzed method, considering their potential applications for photodynamic therapy. Absorption properties in near-infrared regions may provide these dyes to be applicable in optical recording media, biological fluorescent stains and probes. Synthesis details and full spectroscopic characterizations of the cyanines were described.