Theoretical investigation of one-photon and two-photon absorption properties for multiply N-confused porphyrins

We have theoretically investigated a series of multiply N-confused porphyrins and their Zn or Cu complexes for the first time by using DFT(B3LYP/6-31G*) and ZINDO/SOS methods. The electronic structure, one-photon absorption (OPA), and two-photon absorption (TPA) properties have been studied in detail. The calculated results indicate that the OPA spectra of multiply N-confused porphyrins are red-shifted and the OPA intensities decrease compared to normal porphyrin. The maximum two photon absorption wavelengths lambda(max) are blue-shifted and the TPA cross sections delta(max) are increased 22.7-112.1 GM when the N atoms one by one are inverted from core to beta position to form multiply N-confused porphyrins. Especially delta(max) of N3CP get to 164.7 GM. The electron donors -C6F5s at meso-position can make the TPA cross section delta(max) increase. After forming metal complexes with Cu or Zn, the TPA properties of multiply N-confused porphyrins are further increased except for N3CP, N4CP. Our theoretical findings demonstrate that the multiply N-confused prophyrins as well as their metal complexes and derivatives are promising molecules that can be assembled series of materials with large TPA cross section, and are sure to be the subject of further investigation.