This study shows the synthesis and characterization of 4,5-bis(4-propionylphenoxy)phthalonitrile (2) and its octa-substituted phthalocyanine derivatives [ZnPc(3), CuPc(4), and CoPc(5)]. A combination of standard spectroscopic techniques has characterized the newly synthesized phthalonitrile derivative and phthalocyanines. The aggregation behaviors of new octa-substituted phthalocyanines have been evaluated by ultraviolet-visible (UV-vis) spectroscopy. The metal ion-sensitive behaviors of new octa-substituted phthalocyanines in the presence of soft metal ions have been performed by UV-vis and fluorescence spectrophotometer. The quenching efficiency (K-sv) of Ag+ ions against ZnPc(3) was found using the Stern-Volmer equation. The binding constant (K-a) and binding stoichiometry (n) of ZnPc(3) with Ag+ ions were calculated using the modified Benesi-Hildebrand equation. Sensitive protonation behaviors of octa-substituted phthalocyanines have been investigated by titration experiments as well as computational calculations. The ZnPc(3) and CuPc(4) were exhibited H-type aggregation behaviors toward Ag+ ions. However, the protonation of octa-substituted zinc and copper phthalocyanine during the titration with HCl caused J-type self-aggregation properties. In vitro antioxidant properties of the new compounds were investigated by the radical scavenging ability of 1,1-diphenyl-2-picrylhydrazyl (DPPH), chelating ability to ferrous ions, and reducing power methods. Additionally, in vitro antibacterial activities of the octa-substituted phthalocyanines were determined. Finally, optimized structures of novel compounds [(2), ZnPc(3), CuPc(4), and CoPc(5)] were obtained on the HF (Hartree-Fock), B3LYP (Becke, 3-parameter, Lee-Yang-Parr), M06-2X methods with 3-21 g, 6-31 g and SDD basis set. Then, biological activities of novel phthalonitrile and its phthalocyanine derivatives toward breast, liver, and lung cancer proteins were compared with molecular docking studies.