This thesis introduces a brief review of the phenomena of fluorescent dyes, then a discussion on the synthesis and applications of water-soluble squaraine dyes. It then transitions to the discussion of the synthesis and characterization of hydrophilic and hydrophobic squaraine dye derivatives of indolenine as well as the synthesis of a selection of benzothiazole derived pentamethine cyanine dyes with a meso-pyridine substituent. The structural identification of these compounds was performed using various spectroscopic techniques. Experiments confirmed in the later portion of the thesis characterize the optical properties including solvatochromism and pH responsiveness.