Synthesis and optical properties of cationic cyclopentadienyl iron complexes with diphenylacetylene chromophores

•Six novel cationic cyclopentadienyl iron complexes with diphenylacetylene chromophore were prepared.•Bearing phenylacetylene resulted in a red shift in the UV–Vis absorption spectra.•Five cationic cyclopentadienyl iron complexes show large two-photon absorption (TPA) cross section.

Cationic cyclopentadienyl iron complexes of arenes are applied in photopolymerization and photocatalysis because of their good photophysical and photochemical properties. In this study, a series of cationic cyclopentadienyl iron complexes with diphenylacetylene chromophores (Aky-Fc) was obtained via nucleophilic substitution and Suzuki coupling reactions. The linear and nonlinear optical properties of the obtained molecules were tuned by phenylethynyl linkages. The UV–Vis absorption spectra showed that increasing the conjugation by substituting phenylacetylene spacer resulted in a red shift in the absorption bands and much stronger absorption in Aky-Fc than in (η6-cumene) (η5-cyclopentadienyl) iron hexafluorophosphate (I-261). With the single-beam Z-scan technique, the nonlinear absorption of Aky-Fc showed that Aky-Fc (8), (9), and (10) had good nonlinear optical ability, and the two photon absorption (TPA) cross section σ was approximately 10 times that of I-261.

Graphical abstractThe electrostatic potential figure and the single-beam Z-scan curve of 10 are shown here. 10 showed excellent nonlinear optical ability, and the two photon absorption (TPA) cross section σ was approximately 10 times that of (η6-cumene) (η5-cyclopentadienyl) iron hexafluorophosphate (I-261).Figure optionsDownload full-size imageDownload as PowerPoint slide