In this study, two SiPcs have been selected and the photodynamic therapy potentials were evaluated of the Pcs. Synthesis of Axially 2-decyn-1-oxy disubstituted Es-SiPc-2 was newly synthesized by the reaction of SiPcCl2 with 2-decyn-1-ol in the presence of NaH in toluene. Furthermore, their nuclear imaging potentials were evaluated in human colon adenocarcinoma (HT-29) and human lung fibroblast cell (WI-38) cell lines. The uptake results have indicated that Es-SiPc labeled with I-131 radionuclide (I-131-Es-SiPc) was approximately 2-fold higher in the HT-29 cell line than the WI-38 cell line. In other words, the target/non-target tissue ratio is defined as two in the HT-29/WI-38 cell lines. Besides, the uptake values of I-131-Es-SiPc were found to be higher than I-131-Es-SiPc-2. I-131-Es-SiPc and I-131-Es-SiPc-2 are promising for imaging or treating colon adenocarcinoma. In vitrophotodynamic therapy (PDT) studies have shown that both compounds are suitable and can be used in this field. Also, Es-SiPc has been shown to have higher phototoxicity than Es-SiPc-2.