This thesis reports the synthesis of new near infrared dyes in three chapters. The first two chapters outline the synthetic procedure for synthesizing mono- and pentamethine cyanine dyes. The initial chapter encompasses the synthesis of asymmetric monomethine dyes with red-shifted optical properties. The second chapter involves the synthesis and assessment of new symmetrical quinolin-4-yl and phenanthridin-6-yl pentamethine dyes as potential oxidative DNA cleavage agents. The last chapter of the thesis details the synthesis and evaluation of new phenoxizinum dyes as contrast agents for insulunomia, a pancreatic cancer. Furthermore, all new compounds were characterized via NMR and their coherent optical properties were obtained.