Two-\u200bphoton absorption of Zn(II) octupolar molecules

In this work we present an investigation of the non-linear optical (NLO) properties of two octupolar chromophores: [Zn(4,4\u2032-bis(dibutylaminostyryl) -[2,2\u2032]-bipyridine)3]2+ and [Zn(4,4\u2032-bis((E)- 2-(N-(TEG)pyrrol-2-yl)vinyl)-[2,2\u2032]-bipyridine)3]2+ with Zn(II) as the coordination center, using two-photon emission technique (TPE) in fs-pulse temporal regime. Compared to the free ligands, our results do not show a net increase in the two-photon absorption (TPA) cross-section for the octupolar complexes, once normalized to the ligand unit. This is in partial disagreement with a previous theoretical study investigating the first molecule where a significant increase of the TPA cross-section was predicted (X. J. Liu, et al., J. Chem. Phys., 2004, 120, 11 493)