A comparative study of one- and two-photon absorption properties of meso–meso singly, meso-β doubly and meso–meso β–β β–β triply linked ZnII-porphyrin oligomers

The electronic structures, one-photon absorption (OPA) and two-photon absorption (TPA) properties of the meso – meso singly, the meso -β doubly and the meso – meso β–β β–β triply linked Zn II -porphyrin dimers and trimers have been comparatively studied by using the hybrid B3LYP functional combined with the 6-31G basis set and ZINDO-SOS methods. The results show that on going from the dimers to the trimers, due to the increased conjugation chain, the maximum TPA positions are red-shifted and the maximum TPA cross sections produce a remarkable enhancement. The calculated maximum TPA cross sections of the studied molecules are in the range of 25.4–616.3 × 10 −48 cm 4 s/photon. Compared with the meso – meso singly linked Zn II -porphyrin derivatives, the meso -β doubly and the meso – meso β–β β–β triply linked Zn II -porphyrin derivatives have larger TPA cross sections at 700–1000 nm. They are promising candidates for TPA materials.