Synthesis and photochemical properties of cationic cyclopentadienyliron containing arylazo chromophores

Two kinds of cationic cyclopentadienyliron complexes containing arylazo chromophores (Azo-Fc) were synthesized through the nucleophilic aromatic substitution reactions of cyclopentadienyliron chlorobenzene complexes. The synthesized Azo-Fc was characterized by LC–MS, IR, and 1H NMR. The influence of substituents and the aryl ring on spectral data of the synthesized compounds is described. Unlike other cationic cyclopentadienyliron complexes, Azo-Fc hardly underwent photolysis and showed no photo-initiating abilities in the cationic polymerization under photo-irradiation; in addition, trans/cis isomerization by irradiation is possible at different wavelengths.

Two kinds of cationic cyclopentadienyliron complexes containing arylazo chromophores which can undergo trans/cis isomerization by irradiation at different wavelengths were investigated.Figure optionsDownload as PowerPoint slideHighlights
► Six new cationic cyclopentadienyliron complexes containing arylazo chromophores (Azo-Fc) were synthesized.
► UV–vis results showed that Azo-Fcs have strong absorption in the regions 300–450 nm.
► Unlike other cationic cyclopentadienyliron complexes, Azo-Fcs cannot undergo photolysis under a halogen lamp.
► Azo-Fcs can undergo reversible trans/cis isomerization by irradiation at different wavelengths.