Large two photon absorption cross section of asymmetric Zn(II) porphyrin complexes substituted in the meso or β pyrrolic position by -CC-C6H4X moieties (X = NMe2, NO2)

TPA spectra of Zn(II) porphyrins in the B band spectral region substituted with D/A groups in the meso and β pyrrolic poisition.