Porphyrin-based compounds have good electronic and optical properties, which can be beneficial for use in optoelectronics. In this paper, the electronic and optical properties of porphyrin, PAI, and PMg were studied using the DFT and TD-DFT methods. The HOMO-LUMO analysis showed that the energy gap decreased significantly for the modified compounds. Among the modified compounds, PMg showed the lowest energy gap and the highest flexibility. The DOS analysis showed that the density of states increased near the Fermi level for the modified compounds, especially PMg. The TD-DFT analysis showed that the transition energy for the porphyrin compound was weak, with ? = 489.27 nm and f = 0.0075. For the PMg compound, the transition energy was strong, with ? = 458.11 nm and f = 0.6480, which indicated a highly allowed transition. The results showed that the PMg compound performed well in the electronic and optical properties, which makes it a good candidate for use in optoelectronics and lasers.