Synthesis and optical properties of novel D-π-A-π-D type cationic cyclopentadienyliron complexes of arenes

Article abstract of DOI:10.1039/c5ra08989a

Diphenylethynyl chromophores were successfully introduced into the arene ligands of cationic cyclopentadienyliron complexes through nucleophilic substitution and Suzuki coupling reactions. Three novel cationic cyclopentadienyliron complexes with symmetrical di(4-methoxy-phenylethynyl) chromophores (CFSs) were obtained and completely characterized by IR, ¹H NMR, ¹³C NMR, and MS. The linear and nonlinear optical properties of the obtained molecules were tuned using 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 a stronger absorption in CFSs than in the previously reported (η⁶-cumene)(η⁵-cyclopentadienyl)iron hexafluorophosphate (I-261). These cross-conjugated D-π-A-π-D type compounds also showed larger third-order nonlinear susceptibility than I-261.