Figure 1.

Trimethine cyanine analogs used in the current study. The modifications performed on the parent cyanine (24) are highlighted in different colors (compounds 25–32). The detailed synthetic procedure is described in Section 4.1. All compounds have one positive charge on the cyanine system and most have charged alkyl amine substituents. The synthesis and characterization of the related pentamethine cyanine analogs (compounds 1–23) are previously reported [18].