Two-photon absorption properties of porphyrin derivatives

Using density functional theory and ZINDO-SOS method, the two-photon absorption properties of a series of porphyrin derivatives have been theoretically investigated. The calculated results are in good agreement with the experimental observations. It is found that the central porphyrin moiety has the electron-donating ability, which is favor of the charge transfer from the center to the electron acceptor ends. As a consequence, the compound [5,15-bis[(4′-nitrophenyl)ethynyl]-10,20-diphenylporphinato]zinc(II) presents the largest two-photon absorption cross-section - 3279×10 ^-50cm⁴s/photon, which is more than 100 times as that for (porphinato)-zinc (II). This type of symmetrically substituted porphyrin derivatives will be a promising direction for further development of novel TPA dyes.