Spectroscopic investigation, DFT, NBO and TD-DFT calculation for porphyrin (PP) and porphyrin-based materials (PPBMs)

Abstract

The porphyrin and its derivatives are very important, as they are characterized by photo dynamic therapy (PDT), conjugation structures, and good optical properties and are sensitive materials to harmful elements such as mercury which damage the central nervous system brain. Therefore, in our study, it was important to conduct some computational studies such as the density functional theory (PDT), time-dependent density functional theory (TD-DFT) and natural bond orbital (NBO). The influence of different substituents such as phenyl, pyridyl, nitrophenyl, hydroxy‑3,5 dimethoxyphenyl and 3-ethoxy-2‑hydroxy-phenyl sodium sulfonate on the molecular structure parameters of porphyrin (PP) (especially in methine (=CH-) site of PP) are studied using DFT/M06–2X/6–311G(d) method. Using TD/M06–2X/6–311G++(d, p) method, the electronic absorption spectra for porphyrin (PP), tetrakis(4-nitrophenyl) porphyrin (TNPPP) and 5,10,15,20-tetrakis (4‑hydroxy-3,5 dimethoxyphenyl) porphyrin (THMPPP) in methanol. In addition to, the natural bond orbital (NBO) analysis is investigated for TPP complexes using DFT/LanL2DZ/6–311 G (d) method in gaseous state.