Strong two-photon absorption properties and ultrafast pump-probe studies of novel porphyrin derivatives

Herein we report strong two-photon absorption (2PA) properties and ultrafast pump-probe dynamics of five novel porphyrin derivatives. The investigated molecules were β-octamethoxyporphyrin (H2OMP), its Zn(II)-derivative (ZnOMP) and 3,8,13,18-tetrachloro-2,7,12,17-tetramethoxyporphyrin (H2TCTMP), and its Zn(II)- and Ni(II)-derivatives i.e. ZnTCTMP and NiTCTMP respectively. NLO coefficients were obtained from the Z-scan measurements using ∼2 ps pulses at 800 nm. Open aperture data confirmed 2PA whereas closed aperture data indicated positive nonlinearity. 2PA cross-sections in the range of 103–104 GM were recorded. Femtosecond pump-probe results at 600 nm of above compounds demonstrated triple exponential decay pattern indicating three lifetimes arising from high lying excited states.